This document provides details on biochemical tests performed on various bacteria. Lab 4 describes tests on Enterobacteriaceae including TSI, SIM, MR-VP, urea, and MacConkey/Hektoen plates. Lab 6 describes additional tests like phenol red with sugars, gelatin, litmus milk, nitrate broth, and casein plate. The results help identify features of bacteria like fermentation abilities and enzyme production. Bergey's Manual was also discussed as a tool to identify unknown bacteria based on characteristics.
This document provides descriptions of various microbiological tests and media, including what each tests for and how to interpret the results. It explains that Phenol Red Broth tests for carbohydrate fermentation by detecting acid production which turns the broth yellow, Durham tubes test for gas production by detecting bubbles, and O.F. Basal Medium distinguishes between oxidation and fermentation by adding oil to cut off oxygen in one tube. Similarly, it outlines several other common differential and selective tests and media, such as Citrate Agar, Decarboxylase Broth, TSB for indole production, Nitrate Broth, Urease Broth, Blood Agar for hemolysis, PEA agar for gram-
Microbiology Practical 2!!!! i will miss this class! (Ilana Kovach)Ilana Kovach
The document describes several microbiology techniques used to identify bacterial species including biochemical tests to determine enzyme production from substrates and differential and selective media. Identification of both gram-positive and gram-negative bacteria is discussed along with their reactions in tests such as catalase, coagulase, triple sugar iron, lysine iron agar, and rapid identification methods for pathogenic species.
Medical Microbiology Laboratory (biochemical tests - ii)Hussein Al-tameemi
1. The document discusses various biochemical tests used to identify bacteria, including enzymatic tests, metabolic pathway tests, and specific tests.
2. Metabolic pathway tests include carbohydrate oxidation/fermentation tests like the oxidative fermentation test, carbohydrate fermentation in TSI agar, and methyl red and Voges-Proskauer tests. They also include amino acid degradation tests and single substrate utilization tests.
3. Examples of specific tests discussed are the citrate utilization test and acetate utilization test to determine if bacteria can use certain compounds as the sole carbon source.
This document provides a summary of common laboratory biochemical assays used to identify bacteria:
1. Staining techniques like Gram stain, acid-fast stain, spore stain, and capsule stain are used to distinguish bacteria based on cell wall structure and presence of structures.
2. Differential and selective media like Mannitol Salt Agar, Blood Agar, MacConkey Agar, and Eosin Methylene Blue Agar are used to isolate and distinguish bacteria based on metabolic characteristics and reactions.
3. Biochemical tests like carbohydrate fermentation, starch hydrolysis, gelatin liquefaction, Triple Sugar Iron, IMViC, citrate utilization, and litmus milk are used to determine a bacteria
This document discusses methods for identifying Enterobacteriaceae bacteria, including biochemical tests like IMViC and the Triple Sugar Iron (TSI) agar test. IMViC tests examine indole production, methyl red reaction, Voges-Proskauer reaction, and citrate utilization. The TSI agar test detects glucose, lactose and sucrose fermentation, gas production, and hydrogen sulfide production. These tests can identify bacteria such as E. coli, Klebsiella, and Proteus based on their biochemical characteristics and reactions in the assays.
Sugar fermentation tests, Cetrimide agar medium, Hugh Leifson medium Shivam kumar Sriwas
1. The document discusses sugar fermentation, how to test for it using media like phenol red carbohydrate broth, and the interpretation of results.
2. Hugh Leifson medium and Cetrimide agar are described as media used to differentiate bacterial metabolism and isolate Pseudomonas aeruginosa, respectively.
3. Key components, principles, preparation, and expected results are outlined for both Hugh Leifson medium and Cetrimide agar tests.
The carbohydrate fermentation test is used to determine whether a bacterium can utilize a certain carbohydrate or not.
It tests for the presence of acid and/gas produced from the fermentation of a single carbohydrate.
This document discusses biochemical tests used to identify Enterobacteriaceae bacteria, including the Triple Sugar Iron test, IMViC tests (Indole, Methyl Red, Voges-Proskauer, Citrate), and other tests like Urease, Phenylalanine Deaminase, and Nitrate Reductase. It provides details on the procedures and expected results of each test to differentiate bacteria based on their ability to ferment sugars, produce enzymes, and catalyze other biochemical reactions.
This document provides descriptions of various microbiological tests and media, including what each tests for and how to interpret the results. It explains that Phenol Red Broth tests for carbohydrate fermentation by detecting acid production which turns the broth yellow, Durham tubes test for gas production by detecting bubbles, and O.F. Basal Medium distinguishes between oxidation and fermentation by adding oil to cut off oxygen in one tube. Similarly, it outlines several other common differential and selective tests and media, such as Citrate Agar, Decarboxylase Broth, TSB for indole production, Nitrate Broth, Urease Broth, Blood Agar for hemolysis, PEA agar for gram-
Microbiology Practical 2!!!! i will miss this class! (Ilana Kovach)Ilana Kovach
The document describes several microbiology techniques used to identify bacterial species including biochemical tests to determine enzyme production from substrates and differential and selective media. Identification of both gram-positive and gram-negative bacteria is discussed along with their reactions in tests such as catalase, coagulase, triple sugar iron, lysine iron agar, and rapid identification methods for pathogenic species.
Medical Microbiology Laboratory (biochemical tests - ii)Hussein Al-tameemi
1. The document discusses various biochemical tests used to identify bacteria, including enzymatic tests, metabolic pathway tests, and specific tests.
2. Metabolic pathway tests include carbohydrate oxidation/fermentation tests like the oxidative fermentation test, carbohydrate fermentation in TSI agar, and methyl red and Voges-Proskauer tests. They also include amino acid degradation tests and single substrate utilization tests.
3. Examples of specific tests discussed are the citrate utilization test and acetate utilization test to determine if bacteria can use certain compounds as the sole carbon source.
This document provides a summary of common laboratory biochemical assays used to identify bacteria:
1. Staining techniques like Gram stain, acid-fast stain, spore stain, and capsule stain are used to distinguish bacteria based on cell wall structure and presence of structures.
2. Differential and selective media like Mannitol Salt Agar, Blood Agar, MacConkey Agar, and Eosin Methylene Blue Agar are used to isolate and distinguish bacteria based on metabolic characteristics and reactions.
3. Biochemical tests like carbohydrate fermentation, starch hydrolysis, gelatin liquefaction, Triple Sugar Iron, IMViC, citrate utilization, and litmus milk are used to determine a bacteria
This document discusses methods for identifying Enterobacteriaceae bacteria, including biochemical tests like IMViC and the Triple Sugar Iron (TSI) agar test. IMViC tests examine indole production, methyl red reaction, Voges-Proskauer reaction, and citrate utilization. The TSI agar test detects glucose, lactose and sucrose fermentation, gas production, and hydrogen sulfide production. These tests can identify bacteria such as E. coli, Klebsiella, and Proteus based on their biochemical characteristics and reactions in the assays.
Sugar fermentation tests, Cetrimide agar medium, Hugh Leifson medium Shivam kumar Sriwas
1. The document discusses sugar fermentation, how to test for it using media like phenol red carbohydrate broth, and the interpretation of results.
2. Hugh Leifson medium and Cetrimide agar are described as media used to differentiate bacterial metabolism and isolate Pseudomonas aeruginosa, respectively.
3. Key components, principles, preparation, and expected results are outlined for both Hugh Leifson medium and Cetrimide agar tests.
The carbohydrate fermentation test is used to determine whether a bacterium can utilize a certain carbohydrate or not.
It tests for the presence of acid and/gas produced from the fermentation of a single carbohydrate.
This document discusses biochemical tests used to identify Enterobacteriaceae bacteria, including the Triple Sugar Iron test, IMViC tests (Indole, Methyl Red, Voges-Proskauer, Citrate), and other tests like Urease, Phenylalanine Deaminase, and Nitrate Reductase. It provides details on the procedures and expected results of each test to differentiate bacteria based on their ability to ferment sugars, produce enzymes, and catalyze other biochemical reactions.
Physical Factors: Temperature,Physical Factors: pH of the Extracellular Envir...Md Azizul Haque
The document describes an experiment to determine the pH requirements of microorganisms. It explains that microbial growth is influenced by environmental pH, with each species having an optimal pH range for growth, usually between pH 4-9 for bacteria. The experiment aims to observe the growth of different microbes at various pH levels to determine their pH classifications as acidophilic, neutralophilic, or alkalophilic.
The document discusses various biochemical tests used to identify microorganisms (M.Os). It describes tests such as decarboxylase tests to detect amino acid decarboxylation; carbohydrate fermentation tests to detect sugar utilization; starch hydrolysis and citrate utilization tests; gelatin liquefaction; coagulase production; and phenylalanine deamination. It also discusses triple sugar iron agar tests, casein digestion, urease production, methyl red/Voges-Proskauer tests, and other assays. The purpose is to biochemically characterize M.Os and diagnose bacteria based on their metabolic properties and enzyme production.
Module 5b biochemical activities for the labHuang Yu-Wen
This document summarizes various biochemical tests used to identify bacteria, including:
- Fermentation tests using Durham tubes to detect gas and acid production from carbohydrates.
- The IMVIC series of tests (Indole, Methyl Red, Voges-Proskauer, Citrate) which identify metabolic pathways and substrate utilization through color changes.
- Other common tests like catalase, coagulase, urease, and oxidase which detect enzymatic activity through production of gas or color changes.
Students are assigned to prepare SIM, MRVP, and SCA media, inoculate bacterial samples, interpret test results using described reagents and expected color changes, and submit a write-
The methyl red test determines a bacterial culture's ability to ferment glucose by producing stable acidic end products. Bacteria that can metabolize glucose through the mixed acid pathway will lower the broth pH below 4.5, causing the methyl red indicator to change from yellow to red. The test involves inoculating glucose phosphate broth with a bacterial culture and incubating. After 48 hours, methyl red indicator is added and a color change from yellow to red/orange indicates the culture fermented glucose and tested positive.
The Seliwanoff's test distinguishes between aldose and ketose sugars. It involves heating the sugar with resorcinol and hydrochloric acid. Ketoses are more rapidly dehydrated than aldoses under these conditions. The dehydrated ketose will react with resorcinol to produce a deep cherry red color, indicating a positive test. Aldoses may produce a faint pink color. Fructose and sucrose give a positive test since sucrose contains fructose. The test exploits the difference in reactivity between aldehyde and ketone functional groups.
Carbohydrate Fermentation, Tripe Sugar Iron Agar Test, IMViC Test Part A Indo...Md Azizul Haque
This document appears to be a microbiology lab report submitted by a student. It includes 3 experiments:
1. A carbohydrate fermentation experiment to test bacteria's ability to ferment carbohydrates and produce organic acids or gases.
2. A Triple Sugar Iron test to determine bacteria's ability to ferment glucose, lactose, and sucrose, and produce hydrogen sulfide.
3. An IMViC test (part A was the Indole test) to detect the formation of indole from tryptophan by bacterial enzymes.
The document provides objectives, principles, procedures and results for each experiment with the aim of identifying bacterial species based on their biochemical reactions. It includes tables, diagrams
Alshaheer Corporation provides microbiological, chemical, and water quality testing services. The document outlines the various tests conducted on meat, slides, areas of a processing facility, hands/swabs of workers, water, and the reverse osmosis plant. Tests are performed to detect bacteria like E. coli, Salmonella, and Staphylococcus aureus, as well as assess water quality parameters like hardness, pH, and chlorine levels.
The document provides instructions for performing several microbiological tests, including sugar fermentation tests, indole production, methyl red, Voges-Proskauer, citrate utilization, nitrate reduction, urease, triple sugar iron, oxidase, catalase, amylase, and lipase. It explains the principles, expected results, and interpretations for each test. The tests can be used to differentiate bacterial species and determine their metabolic abilities.
1) The document discusses several microbiological tests including sugar fermentation, indole, methyl red, Voges-Proskauer, and citrate utilization tests.
2) These tests help determine if microbes can ferment sugars, produce certain enzymes, and utilize various carbon sources for energy.
3) The results of the tests are indicated by color changes in growth media or production of gas, which helps identify different bacterial species or their metabolic abilities.
This document discusses various methods for identifying microbes, including molecular identification methods and physiological identification methods. Molecular identification methods analyze conserved genetic regions like the 16S rRNA gene to determine evolutionary relationships. Physiological identification methods examine morphological, physical, and biochemical traits of microbes like cell structure, temperature tolerance, and carbohydrate utilization through tests.
Practical microbiology dr.nada khazal k. hendiعليے المرزوكيے
This document discusses various biochemical tests used to identify medical bacteria, including:
- Hemolysis testing on blood agar to detect complete, partial, or no lysis of red blood cells.
- Mannitol fermentation testing to differentiate between S. aureus and S. epidermidis.
- Tests for pigment production, motility, catalase production, coagulase production, oxidase activity, carbohydrate fermentation, and utilization of resources like urea, citrate, and tryptophan.
- The IMViC battery of tests including indole production, methyl red, Voges-Proskauer, and citrate utilization tests to identify enteric gram-negative bacilli.
1. The document discusses several microbiological tests used to identify microbes, including sugar fermentation tests, indole tests, methyl red tests, Voges-Proskauer tests, citrate utilization tests, nitrate reduction tests, urease tests, triple sugar iron tests, oxidase tests, and catalase tests.
2. The tests work by examining how microbes metabolize certain substrates like sugars or amino acids, detecting changes in pH, color changes with indicators, or production of gases.
3. The results of these tests can be used to differentiate between bacterial species and determine their metabolic abilities under aerobic or anaerobic conditions.
This document discusses several physiological tests used to identify microbes based on their biochemical properties and reactions. It describes tests such as sugar fermentation, indole production, methyl red, Voges-Proskauer, citrate utilization, nitrate reduction, and more. Each test examines how microbes metabolize certain substrates like carbohydrates or amino acids and analyzes physical responses like color changes or gas production to determine whether microbes are positive or negative for desired biochemical pathways and properties.
The document discusses methods for identifying bacteria, including phenotypic, immunological, and genetic techniques. Phenotypic methods examine bacterial morphology, staining characteristics, and biochemical reactions. Tests like Gram staining, colony morphology, and catalase can provide initial identification. Further tests of carbohydrate use, enzyme production, and sensitivity to inhibitors allow identification to the species level. Immunological methods detect bacterial antigens, while genetic techniques like PCR and nucleic acid analysis provide accurate identification by examining microbial DNA. Both traditional and molecular methods are used to fully characterize unknown bacteria.
The document discusses biochemical tests called IMViC tests that are used to identify bacteria, especially in the coliform group.
The IMViC tests include Indole, Methyl Red, Voges-Proskauer, and Citrate tests. These tests help distinguish members of the Enterobacteriaceae family based on how they metabolize different substrates.
The document provides details on how each test is performed and interpreted. It gives examples of reactions for common bacteria like E. coli, Salmonella, Klebsiella, and Proteus species. While most aerobic bacteria are citrate positive, E. coli is citrate negative despite being an aerobic bacterium.
Biochemical tests for bacterial identificationSuprakash Das
Basic biochemical tests for identification of most common bacteria along with their principles and methods to perform and quality control for UG & PG Students.
Pseudomonas was identified as the unknown bacteria through a series of tests. Microscopic analysis showed the bacteria was rod-shaped and 2.5-3 um in size. A gram stain revealed it was gram-negative. Aerobic growth tests showed it was a strict aerobe. Biochemical tests such as oxidase and glucose oxidation and fermentation ruled out other possibilities and identified the bacteria as Pseudomonas. Further tests of catalase and endospore formation confirmed this identification.
This document provides information on various biochemical tests performed for the identification of gram-negative bacteria, including catalase, cytochrome oxidase, indole, methyl red, Voges-Proskauer, citrate utilization, urea hydrolysis, triple sugar iron, sugar fermentation, oxidation-fermentation, nitrate reduction, and decarboxylase tests. It describes the principles, procedures, reagents, and expected results for each test as well as example organisms that would produce positive or negative reactions. Quality control organisms are also listed to ensure the validity of the test results.
This document discusses methods for identifying Enterobacteriaceae bacteria, including biochemical tests like IMViC and the Triple Sugar Iron (TSI) agar test. IMViC tests examine indole production, methyl red reaction, Voges-Proskauer reaction, and citrate utilization. The TSI agar test detects glucose, lactose and sucrose fermentation, gas production, and hydrogen sulfide production. These tests can identify bacteria such as E. coli, Klebsiella, and Proteus based on their biochemical characteristics and reactions in the assays.
AnswerGas production is characteristic feature with turning of re.pdfaparnawatchcompany
Answer:
Gas production is characteristic feature with turning of red color to yellow color by oxidative
fermentation of \"carbohydrate containing phenol red medium\" normally with bacteria. This is
indicative of positive result due to presence of carbohydrates in the medium. If there is no
\"fermentation occurred in the medium with no gas production\" even in the presence of
carbohydrates in the phenol red medium in after 18 - 24 hours of incubation\" is the indicative of
that particular microbe is \"non-fermenter\" of carbohydrates. Therefore, color change & gas
production (CO2) is the indicative of positive results & absence of these features in the presence
of carbohydrates in the medium is the feature can you look at (within the phenol red broth tube)
to ensure that this is not a false - negative result
Ques-2:
A 1.0% concentration be easier to work in the phenol red medium of Durham tube during this
experiment than a 0.5% concentration because 1% of carbohydrate is \"isotonic for the growth &
fermentation\" of microbial species. This 1% carbohydrates is adequate concentration to make
bacterial cells isotonic to the medium to survive
Explanation:
Oxidative fermentation (OF):
In the given sample, bacteria fermented the carbohydrate (glucose, sucrose) aerobically and the
result is the indicative of acid production in the open culture Durham tube (aerobic respiration
occurred) and oil covered culture tube (anaerobic respiration occurred). The resultant acid
produced converts, bromthymol blue PH indicator colour from green to yellow. We can assess
the PH of the fermented product based on its acidic nature. We cannot determine the amount of
acid produced here and we cannot predict the gas (in the form of bubbles) liberated upon OF
which is significant to identify a particular unknown bacteria inside the medium. The turbidity
inside the yellow broth represents bacterial motility.
Phenol red (PR) based broth is useful to ferment carbohydrates in presence of bacteria (gram
negative) finally thereby production of gas (possibly CO2) and acids. PR based broth is useful to
examine the ability to ferment the carbohydrates by the bacteria and the ability to degrade the
amino acids. PR based broth in presence of carbohydrates with the above OF produces orange
coloured turbidity with a proper optical density. In the absence of the carbohydrates bacteria
cannot form orange colour due to absence of fermentation.
Solution
Answer:
Gas production is characteristic feature with turning of red color to yellow color by oxidative
fermentation of \"carbohydrate containing phenol red medium\" normally with bacteria. This is
indicative of positive result due to presence of carbohydrates in the medium. If there is no
\"fermentation occurred in the medium with no gas production\" even in the presence of
carbohydrates in the phenol red medium in after 18 - 24 hours of incubation\" is the indicative of
that particular microbe is \"non-fermenter\" of carbohydrates. There.
Physical Factors: Temperature,Physical Factors: pH of the Extracellular Envir...Md Azizul Haque
The document describes an experiment to determine the pH requirements of microorganisms. It explains that microbial growth is influenced by environmental pH, with each species having an optimal pH range for growth, usually between pH 4-9 for bacteria. The experiment aims to observe the growth of different microbes at various pH levels to determine their pH classifications as acidophilic, neutralophilic, or alkalophilic.
The document discusses various biochemical tests used to identify microorganisms (M.Os). It describes tests such as decarboxylase tests to detect amino acid decarboxylation; carbohydrate fermentation tests to detect sugar utilization; starch hydrolysis and citrate utilization tests; gelatin liquefaction; coagulase production; and phenylalanine deamination. It also discusses triple sugar iron agar tests, casein digestion, urease production, methyl red/Voges-Proskauer tests, and other assays. The purpose is to biochemically characterize M.Os and diagnose bacteria based on their metabolic properties and enzyme production.
Module 5b biochemical activities for the labHuang Yu-Wen
This document summarizes various biochemical tests used to identify bacteria, including:
- Fermentation tests using Durham tubes to detect gas and acid production from carbohydrates.
- The IMVIC series of tests (Indole, Methyl Red, Voges-Proskauer, Citrate) which identify metabolic pathways and substrate utilization through color changes.
- Other common tests like catalase, coagulase, urease, and oxidase which detect enzymatic activity through production of gas or color changes.
Students are assigned to prepare SIM, MRVP, and SCA media, inoculate bacterial samples, interpret test results using described reagents and expected color changes, and submit a write-
The methyl red test determines a bacterial culture's ability to ferment glucose by producing stable acidic end products. Bacteria that can metabolize glucose through the mixed acid pathway will lower the broth pH below 4.5, causing the methyl red indicator to change from yellow to red. The test involves inoculating glucose phosphate broth with a bacterial culture and incubating. After 48 hours, methyl red indicator is added and a color change from yellow to red/orange indicates the culture fermented glucose and tested positive.
The Seliwanoff's test distinguishes between aldose and ketose sugars. It involves heating the sugar with resorcinol and hydrochloric acid. Ketoses are more rapidly dehydrated than aldoses under these conditions. The dehydrated ketose will react with resorcinol to produce a deep cherry red color, indicating a positive test. Aldoses may produce a faint pink color. Fructose and sucrose give a positive test since sucrose contains fructose. The test exploits the difference in reactivity between aldehyde and ketone functional groups.
Carbohydrate Fermentation, Tripe Sugar Iron Agar Test, IMViC Test Part A Indo...Md Azizul Haque
This document appears to be a microbiology lab report submitted by a student. It includes 3 experiments:
1. A carbohydrate fermentation experiment to test bacteria's ability to ferment carbohydrates and produce organic acids or gases.
2. A Triple Sugar Iron test to determine bacteria's ability to ferment glucose, lactose, and sucrose, and produce hydrogen sulfide.
3. An IMViC test (part A was the Indole test) to detect the formation of indole from tryptophan by bacterial enzymes.
The document provides objectives, principles, procedures and results for each experiment with the aim of identifying bacterial species based on their biochemical reactions. It includes tables, diagrams
Alshaheer Corporation provides microbiological, chemical, and water quality testing services. The document outlines the various tests conducted on meat, slides, areas of a processing facility, hands/swabs of workers, water, and the reverse osmosis plant. Tests are performed to detect bacteria like E. coli, Salmonella, and Staphylococcus aureus, as well as assess water quality parameters like hardness, pH, and chlorine levels.
The document provides instructions for performing several microbiological tests, including sugar fermentation tests, indole production, methyl red, Voges-Proskauer, citrate utilization, nitrate reduction, urease, triple sugar iron, oxidase, catalase, amylase, and lipase. It explains the principles, expected results, and interpretations for each test. The tests can be used to differentiate bacterial species and determine their metabolic abilities.
1) The document discusses several microbiological tests including sugar fermentation, indole, methyl red, Voges-Proskauer, and citrate utilization tests.
2) These tests help determine if microbes can ferment sugars, produce certain enzymes, and utilize various carbon sources for energy.
3) The results of the tests are indicated by color changes in growth media or production of gas, which helps identify different bacterial species or their metabolic abilities.
This document discusses various methods for identifying microbes, including molecular identification methods and physiological identification methods. Molecular identification methods analyze conserved genetic regions like the 16S rRNA gene to determine evolutionary relationships. Physiological identification methods examine morphological, physical, and biochemical traits of microbes like cell structure, temperature tolerance, and carbohydrate utilization through tests.
Practical microbiology dr.nada khazal k. hendiعليے المرزوكيے
This document discusses various biochemical tests used to identify medical bacteria, including:
- Hemolysis testing on blood agar to detect complete, partial, or no lysis of red blood cells.
- Mannitol fermentation testing to differentiate between S. aureus and S. epidermidis.
- Tests for pigment production, motility, catalase production, coagulase production, oxidase activity, carbohydrate fermentation, and utilization of resources like urea, citrate, and tryptophan.
- The IMViC battery of tests including indole production, methyl red, Voges-Proskauer, and citrate utilization tests to identify enteric gram-negative bacilli.
1. The document discusses several microbiological tests used to identify microbes, including sugar fermentation tests, indole tests, methyl red tests, Voges-Proskauer tests, citrate utilization tests, nitrate reduction tests, urease tests, triple sugar iron tests, oxidase tests, and catalase tests.
2. The tests work by examining how microbes metabolize certain substrates like sugars or amino acids, detecting changes in pH, color changes with indicators, or production of gases.
3. The results of these tests can be used to differentiate between bacterial species and determine their metabolic abilities under aerobic or anaerobic conditions.
This document discusses several physiological tests used to identify microbes based on their biochemical properties and reactions. It describes tests such as sugar fermentation, indole production, methyl red, Voges-Proskauer, citrate utilization, nitrate reduction, and more. Each test examines how microbes metabolize certain substrates like carbohydrates or amino acids and analyzes physical responses like color changes or gas production to determine whether microbes are positive or negative for desired biochemical pathways and properties.
The document discusses methods for identifying bacteria, including phenotypic, immunological, and genetic techniques. Phenotypic methods examine bacterial morphology, staining characteristics, and biochemical reactions. Tests like Gram staining, colony morphology, and catalase can provide initial identification. Further tests of carbohydrate use, enzyme production, and sensitivity to inhibitors allow identification to the species level. Immunological methods detect bacterial antigens, while genetic techniques like PCR and nucleic acid analysis provide accurate identification by examining microbial DNA. Both traditional and molecular methods are used to fully characterize unknown bacteria.
The document discusses biochemical tests called IMViC tests that are used to identify bacteria, especially in the coliform group.
The IMViC tests include Indole, Methyl Red, Voges-Proskauer, and Citrate tests. These tests help distinguish members of the Enterobacteriaceae family based on how they metabolize different substrates.
The document provides details on how each test is performed and interpreted. It gives examples of reactions for common bacteria like E. coli, Salmonella, Klebsiella, and Proteus species. While most aerobic bacteria are citrate positive, E. coli is citrate negative despite being an aerobic bacterium.
Biochemical tests for bacterial identificationSuprakash Das
Basic biochemical tests for identification of most common bacteria along with their principles and methods to perform and quality control for UG & PG Students.
Pseudomonas was identified as the unknown bacteria through a series of tests. Microscopic analysis showed the bacteria was rod-shaped and 2.5-3 um in size. A gram stain revealed it was gram-negative. Aerobic growth tests showed it was a strict aerobe. Biochemical tests such as oxidase and glucose oxidation and fermentation ruled out other possibilities and identified the bacteria as Pseudomonas. Further tests of catalase and endospore formation confirmed this identification.
This document provides information on various biochemical tests performed for the identification of gram-negative bacteria, including catalase, cytochrome oxidase, indole, methyl red, Voges-Proskauer, citrate utilization, urea hydrolysis, triple sugar iron, sugar fermentation, oxidation-fermentation, nitrate reduction, and decarboxylase tests. It describes the principles, procedures, reagents, and expected results for each test as well as example organisms that would produce positive or negative reactions. Quality control organisms are also listed to ensure the validity of the test results.
This document discusses methods for identifying Enterobacteriaceae bacteria, including biochemical tests like IMViC and the Triple Sugar Iron (TSI) agar test. IMViC tests examine indole production, methyl red reaction, Voges-Proskauer reaction, and citrate utilization. The TSI agar test detects glucose, lactose and sucrose fermentation, gas production, and hydrogen sulfide production. These tests can identify bacteria such as E. coli, Klebsiella, and Proteus based on their biochemical characteristics and reactions in the assays.
AnswerGas production is characteristic feature with turning of re.pdfaparnawatchcompany
Answer:
Gas production is characteristic feature with turning of red color to yellow color by oxidative
fermentation of \"carbohydrate containing phenol red medium\" normally with bacteria. This is
indicative of positive result due to presence of carbohydrates in the medium. If there is no
\"fermentation occurred in the medium with no gas production\" even in the presence of
carbohydrates in the phenol red medium in after 18 - 24 hours of incubation\" is the indicative of
that particular microbe is \"non-fermenter\" of carbohydrates. Therefore, color change & gas
production (CO2) is the indicative of positive results & absence of these features in the presence
of carbohydrates in the medium is the feature can you look at (within the phenol red broth tube)
to ensure that this is not a false - negative result
Ques-2:
A 1.0% concentration be easier to work in the phenol red medium of Durham tube during this
experiment than a 0.5% concentration because 1% of carbohydrate is \"isotonic for the growth &
fermentation\" of microbial species. This 1% carbohydrates is adequate concentration to make
bacterial cells isotonic to the medium to survive
Explanation:
Oxidative fermentation (OF):
In the given sample, bacteria fermented the carbohydrate (glucose, sucrose) aerobically and the
result is the indicative of acid production in the open culture Durham tube (aerobic respiration
occurred) and oil covered culture tube (anaerobic respiration occurred). The resultant acid
produced converts, bromthymol blue PH indicator colour from green to yellow. We can assess
the PH of the fermented product based on its acidic nature. We cannot determine the amount of
acid produced here and we cannot predict the gas (in the form of bubbles) liberated upon OF
which is significant to identify a particular unknown bacteria inside the medium. The turbidity
inside the yellow broth represents bacterial motility.
Phenol red (PR) based broth is useful to ferment carbohydrates in presence of bacteria (gram
negative) finally thereby production of gas (possibly CO2) and acids. PR based broth is useful to
examine the ability to ferment the carbohydrates by the bacteria and the ability to degrade the
amino acids. PR based broth in presence of carbohydrates with the above OF produces orange
coloured turbidity with a proper optical density. In the absence of the carbohydrates bacteria
cannot form orange colour due to absence of fermentation.
Solution
Answer:
Gas production is characteristic feature with turning of red color to yellow color by oxidative
fermentation of \"carbohydrate containing phenol red medium\" normally with bacteria. This is
indicative of positive result due to presence of carbohydrates in the medium. If there is no
\"fermentation occurred in the medium with no gas production\" even in the presence of
carbohydrates in the phenol red medium in after 18 - 24 hours of incubation\" is the indicative of
that particular microbe is \"non-fermenter\" of carbohydrates. There.
This document provides information on biochemical tests used to identify bacteria in the family Enterobacteriaceae. It discusses tests such as indole, methyl red/Voges Proskauer, citrate, urease, amino acid decarboxylation, and hydrogen sulfide production. The document also provides tables summarizing the biochemical characteristics and reactions of important genera like E. coli, Salmonella, Klebsiella, and Shigella.
ISOLATION AND IDENTIFICATION OF NLF BACTERIA IN VARIOUS SAMPLES.Daisy Saini
IDENTIFICATION AND ISOLATION OF NON-LACTOSE FEREMNTING BACTERIA IN VARIOUS CLINICAL SAMPLES IN A TERTIARY HOSPITAL IN INDIA, INCLUDE BIOCHEMICAL TEST BASE ON THEIR ENZYMATIC ACTIVITY AND GRAPHICAL PRESENTAION OF THEIR DISTRIBUTION ACCORDING TO SEX RATION , AGE GROUP, SAMPLE AND THEIR PROFILE.
The above presentation provides information regarding the biochemical tests in microbiology. And the core chemical reactions happens during these tests are been explained. The chemical reactions involved in the biochemical tests are been explained with reactions.
This document provides an overview of biochemical methods used for bacterial identification. It discusses why bacterial identification is important, the typical identification scheme involving isolation, staining, culturing, and biochemical/molecular tests. Several common biochemical tests are described in detail, including their principles, media used, and how to interpret results. These tests analyze bacterial metabolism of carbohydrates, proteins, lipids and other compounds. Automated identification systems that can rapidly identify bacteria based on biochemical profiles are also mentioned.
The document describes several members of the Enterobacteriaceae family of bacteria, including Escherichia coli, Klebsiella, and Proteus. It discusses their morphological, cultural, and biochemical characteristics. Members of Enterobacteriaceae are typically gram-negative, facultative anaerobic rods that can be cultured on MacConkey agar. The document outlines the biochemical reactions and properties used to differentiate between lactose-fermenting and non-lactose fermenting bacteria such as E. coli, Klebsiella, and Proteus.
1. Ryla Best
Bio2420.105
Marc Carpenter
Table of Contents
Pg.2---Lab 4: Enterobacteriaceae Biochemical Test
Pg.5---Lab 5: Bergey’s Manual
Pg.6---Lab 6: Biochemical activities of bacteria 2
Pg.10---Appendix
Pg. 1
2. Lab 4: Enterobacteriaceae Biochemical Test
I. Objective/Purpose
The purpose of this lab was to be able to perform different biochemical tests on different
enterobacteriaceae and determine their results.
II. Materials
Test Tube
Test Tube rack
Inoculating loop and needle
Sterile distilled water
Bunsen burner
Tubing
Marker
Petri dish
Hektoen Enteric Medium (HEM) plate
Eosin Methylene Blue (EMB) plate
MacConkey plate
SIM semisolid deeps (Sulfur Indole Motility)
MR-VP broths (Indole, Methyl Red, Voges-Proskauer)
SCA slants (Simmons Citrate Agar)
TSI slants (Triple Sugar Iron)
Urea slants
Kovacs’ reagent
Barritt’s reagent
40% KOH
Bacillus megaterium (Bm)
Kocuria rhizophila (Kr)
Escherichia coli (Ec)
Proteus vulgaris (Pv)
Klebsiella pneumoniae (Kp)
III. Methods
To perform the biochemical tests on the Hektoen, EMB, and MacConkey plates,
the directions from the Enterobacteriaceae Biochemical Test Week 1 handout were
followed and the loop/streak technique was used. The SIM deep instructions were used
on page 157 (steps 1-3) of the Microbiology lab book by John P. Harley. The needle stab
technique was used on page 90 Fig.14.5 of the lab book. The MR-VP broths and the SCA
slants procedure was from page 165-166 Fig. 25.1-25.5 of the lab book. The TSI slants
steps were used from page 140-141 and the urea slants procedure from page 196-197 of
the book. The (Kp) was inoculated under the hood.
IV. Results
Pg. 2
3. TSI
K
r
K
p
P
v
E
c
Slant A A A A
Butt A A A A
Gas + + + +
H2S + - + -
SIM
Bacteria Motility/Indole
Pv +/+
Bm -/-
Ec -/+
Kr -/-
Urea
Bacteria Growth/Urease
Ec -
Pv + strong
Kp + weak
Kr + very weak
EMB
Bacteria Growth
Bm +
Pv -
Pg. 3
SCA
Bacteria Citrate
Kp +
Ec -
Pv +
Kr -
MR-VP
Bacteria Methyl Red/Voges-Proskauer
Bm -/-
Kr -/-
Ec +/-
Pv +/-
Hektoen
Bacteria Growth
Bm -
Pv -
Kr green
Ec coliform
4. Kr -
Ec +
V. Discussion
All the bacteria listed above are in the Enterobacteriaceae family which are all
GG and some are facultative rods. The TSI (Triple Sugar Iron) agar slant test was used to
portray the difference of Enterobacteriaceae from other gram negative bacteria by how
they catabolize glucose, lactose, or sucrose and release sulfides from ammonium sulfate
or sodium thiosulfate. All the bacteria tested for the TSI test (Kr, Kp, Pv, Ec) showed
them all being acidic from the butt and gas end by turning from a red to yellow color as
well as showing gas production by splitting of the agar from the needle stab. This is due
to the glucose, lactose and/or sucrose fermentation of high sugar concentrations. The Kr
and Pv showed H2S formation by observing the blackening of the agar unlike Kp and Ec
with no change of that matter. If the slant remained red with a yellow butt then it had
limited glucose levels and acid formation to be able to increase the pH. If both the slant
and butt remained red, then none of the sugars were fermented and neither gas nor H2S
were produced.
The SCA (Simmons Citrate Agar) test determines if the bacteria uses citrate as a
sole carbon source by having citrate permease that facilitates transport of citrate into the
bacterium that is converted to pyruvic acid and CO2. The Kp and Pv showed positive
citrate by turning the agar from green to blue while the Ec and Kr remained blue. The pH
change is due to the CO2 combined with sodium and water to form sodium carbonate
which is an alkaline product that raises the pH level. Negative citrate like Ec and Kr also
showed no signs of growth.
The SIM (Sulfur Indole Motility) test used to determine the bacteria’s ability to
reduce sulfur-containing amino acids or inorganic sulfur-containing compounds to
produce a gaseous hydrogen sulfide and to determine indole production as well as
motility. Only Pv out of the other bacteria (Bm, Ec, Kr), showed signs of motility by
producing a black precipitate which indicated H2S production and growth was not
restricted to the stab line. No motility is indicated when none of these changes are
observed. The Indole test is used to determine the bacteria’s ability to hydrolyze
tryptophan and produce metabolic products like indole, pyruvic acid and ammonia. Pv
and Ec produced a red layer indicating the presence of indole due to adding the Kovacs’
reagent while the Bm and Kr remained colorless, therefore, tryptophan was not
hydrolyzed.
The MR-VP broth test consisted of using methyl red has a pH indicator to detect
the change of acidity to products such as lactic, acetic, and formic acids. It also uses the
Voges-Proskauer test to identify bacteria that ferment glucose to produce a 2,3-butanediol
compound in the medium. Ec and Pv produced a red layer indicating that they were
Pg. 4
MacConkey
Bacteria Growth
Bm -
Pv -
Kr -
Ec +
5. mixed acid fermenters with a pH of 4 while Bm and Kr did not, which indicated that they
were butanediol fermenters that formed butanediol, acetoin, and fewer organic acids with
a pH of 6, remaining the color yellow. All the bacteria (Bm, Kr, Ec, Pv) remained
colorless when the Barritt’s reagent and 40%KOH was added to the broth to detect the
presence of acetoin, which is a precursor in the synthesis of 2,3-butanediol. The presence
of action would be detected if the broth developed a red color. From the pervious test,
Bm and Kr can be concluded that they form butanediol by other means than using
acetoin.
The Urease Test was used to identify bacteria that are able to produce the enzyme
urease that attacks nitrogen and carbon bonds to form ammonia, CO2, and water. All the
bacteria (Pv, Kp, Kr) showed signs of containing urea due to the color change from
orange to pink except Ec which remained orange. Some bacteria reacted faster than
others because of the shade and volume of pink in the tube. (Strongest to weakest: Pv,
Kp, Kr)
MacConkey and Hektoen plates are selective media which select for gram
negative bacteria through fermentation. Gram positive bacteria won’t be able to grow on
them. The HEM agar contained bile, lactose, and salicin, Coliform enteric bacteria appear
as a salmon to orange tone. Salmonella and Shigella appear as bluish-green and H2S
production turned colonies black within 24-28 hours of incubation if acid is produced.
Bm and Pv showed no signs of growth indicating that they are gram positive bacteria. Kr
appeared green which indicates that it’s a differentiated from Shigella of green, moist,
and raised colonies. Ec showed coliforms that had a salmon color. There was no black
center to be seen which concluded that H2S was not produced by any of the bacteria.
MacConkey agar contain bile salts and crystal violet which inhibit the growth of
gram positive organisms and contains lactose. The red color is used as a pH indicator for
when it changes color, lactose is fermented. Fermentation of lactose produces lactic acid
and decreases pH. The colonies appear as opaque and dark pink to a brick red color.
None of the bacteria (Bm, Kr, Pv) shown signs of growth except Ec which turned bright
red indicating that it’s a lactose fermenter. The other bacteria either are gram positive or
not lactose fermenters.
EMB plates are used to detect and isolate gram negative enteric bacteria. Eosin
and Methylene Blue gives a contrast between lactose fermenting colonies and non-lactose
ones. Sucrose was also added to detect bacteria that ferment more than lactose. Pv and Kr
showed no signs of growth so they are non-lactose fermenters. Ec continues to be seen as
a lactose fermenter. Bm surprisingly showed signs of growth even though its gram
positive and from the above tests shown that it wasn’t a lactose fermenter so this growth
might be due to contamination.
VI. References
Harley, J. Laboratory Exercises in Microbiology. Fifth Edition (2010)
Lab 5: Bergey’s Manual
I. Objective/Purpose
Pg. 5
6. The purpose of this lab was to learn how to use the Bergey’s Manual.
II. Materials
Pencil
Bergey’s Manual
V. Discussion
The Bergey’s Manual is used to help identify bacteria by listing their properties
from temperature range, cell wall, mobility, size to its environment and other side
comments. The Manual can be useful to help identify unknown bacteria by having the
characteristics given or discovering them which can lead to unlocking what their genus is.
Lab 6: Biochemical activities of bacteria 2
I. Objective/Purpose
The purpose of this lab was to be able to perform different biochemical tests on different
enterobacteriaceae and determine their results.
II. Materials
Test Tube
Test Tube rack
Inoculating loop and needle
Sterile distilled water
Bunsen burner
Tubing
Marker
Tape
Petri dish
Phenol Red w/ Durham Tube & Dextrose
Phenol Red w/ Durham Tube & Sucrose
Phenol Red w/ Durham Tube & Lactose
Casein Plate
Starch Plate
Litmus Milk Broth
Gelatin Deep
Nitrate Broth w/ Durham Tube
TSA (tropic soy agar) Catalase
Unknown Bacteria #9
Enterotube
Pg. 6
7. API Strips
Tray
40% KOH
Zinc powder
Gram’s Iodine
Minerial Oil
Escherichia coli (Ec)
Alcaligenes faecalis (Af)
Proteus vulgaris (Pv)
Enterobacter cloacae (Erc)
Bacillus megaterium (Bm)
Lactococcus lactis (Ll)
Staphyloccus epidermidis (Se)
III. Methods
The Enterobacteriaceae Biochemical Test Week2 handout was used to perform
the Litmus Milk Broth and give a layout about the other tests being performed. To
perform the different phenol red with Durham Tube mixtures test, the procedure from
pages 135-136 from the lab book was used. The Casein plate steps were followed from
page 170 of the book and the starch plate was followed from page 148. The needle stab
technique was used on page 90 Fig.14.5 of the lab book for the Gelatin Deeps procedure
on page 174. The Nitrate broth with Durham tube procedure was followed on page 215 of
the lab book and the TSA Catalase test was performed from page 178. The API strip
process was followed on page 221 steps 1-6 and the enterotube procedure on page 228.
IV. Results
See Enterotube and API sheet.
Phenol Red w/ Durhame Tube & Dextrose
Ec Af Pv
Growth + + +
Gas + + +
Color yellow yellow yellow
Phenol Red w/ Durhame Tube & Lactose
Ec Af Pv
Growth + + +
Gas Strong + + +
Color yellow red red
Pg. 7
Phenol Red w/ Durhame Tube & Sucrose
Ec Af Pv
Growt
h
+ + +
Gas + + Strong +
Color orange/yellow yellow yellow
8. Litmus Milk Broth
Ec Pv Bm Ec
Growth + + + +
Gas - - - -
Consistency creamy creamy creamy creamy
Color Dark purple
Growth at
Bottom/light
Dark purple
Growth at
Bottom/light
Dark purple
Growth at
Bottom/light
Dark purple
Growth at
Bottom/cream
Nitrate Broth w/ Durham Tube
Ec Af Pv Se
Growth + + + +
Gas + + + +
Color change w/
Nitrate reagent
red none red red
Color change w/
Zinc
none red none none
Casein Plate
E
c
P
v
Er
c
Growth + + +
Zone of Hydrolysis - - +
V. Discussion
The phenol red as the pH indicator with Durham tube tested for which sugars of
dextrose, sucrose, or lactose could bacteria fermentate from the possible carbohydrates
and if acid is produced. When the tubes are put in the autoclave, the air is expelled from
the tubes which are filled with medium while gas can be produced. The liquid inside the
Durham tubes could entrap the gas to form a bubble. Out of all three sugars, all of the
Pg. 8
Gelatin Deep
E
c
P
v
B
m
Growt
h
+ - -
Liquid - - -
TSA Catalase
E
c
B
m
Er
c
Growt
h
- + +
H2O2 - + +
Starch Plate
E
c
P
v
B
m
Growth + + +
Iodine test - - +
9. bacteria (Ec, Af, Pv) produced growth and gas by having the color change from red to
yellow while the Durham tube wasn’t filled up with the media which indicated the gas
bubble. Pv showed stronger signs with sucrose while Ec showed stronger signs of lactose
by the darker shade of yellow. However, Af and Pv remained red with a gas bubble when
testing with lactose indicates that they used alcohol fermentation. If the tube was filled
with red media and the media was red then no fermentation occurred and vice versa when
the tube is fully filled with yellow media then just acid production occurred. This can be
used to help identify different microorganisms.
Gelatin Deeps were composed of a soluble mixture of polypeptides which the test
could help identify which bacteria can hydrolyze gelatin by secreting the proteolytic
enzyme gelatinase. Only Ec out of the other bacteria (Pv, Bm) produced growth but none
of them remained a liquid but turned into a gel so they all didn’t hydrolyze gelatinase.
Because Ec is a facultative anaerobe, it’s why it was able to still grow in that
environment. If bacteria did hydrolysis by using gelatinase, then the liquid culture would
flow when tilt. The production of gelatinase can be related to the bacteria having the
ability to break down tissue collagen and spread throughout the host which is a good
indicator to discovering the pathogenicity of the bacteria.
Litmus Milk Broth test contains lactose and the protein casein as well as other
vitamins used to identify some bacteria that ferment lactose, proteolyze casein or degrade
both. The metabolic changes can be observed using the pH indicator purple of litmus. All
of the bacteria (Ec, Pv, Bm, Ll) produced growth and all showed no signs of gas
production. The consistency of all the bacteria were creamy and all remained dark purple
which indicates that all the bacteria had an alkaline reaction due to the decarboxylation of
the casein amino acids and not containing the enzyme beta-galactosidase or used a
different way to fermentate it. If O2 was removed by the bacteria, the litmus would
reduce by accepting electrons and have a white zone at the bottom.
The Nitrate Broth with the Durham tube test shows the growing the bacteria with
the nitrate broth to examine the presence of gas and nitrite ions as well as zinc. Some
bacteria use nitrate as a terminal electron acceptor during anaerobic respiration. The gas
is released from the reduction of nitrate and from the citric acid cycle. The bubbles
indicate the presence of nitrogen gas for only nonfermenters. To determine if nitrates
were reduced past nitrite, zince was added. All the bacteria (Ec, Pv, Se, Af) produced
growth and gas which can be produced from carbohydrate sources. When the nitrate
reagent was added, all the bacteria but Af turned red which showed that they all reduce
nitrate except Af. When the zinc reagent was added, only Af turned red which shows that
nitrates were not reduced to nitrites by the bacteria so it must posses other enzymes that
reduce nitrite to ammonia. If the red color did not appear, then the nitrates were reduced
past the nitrite stage to either ammonia or nitrogen gas.
The TSA Catalase test was used to determine if the bacteria contained
flavoproteins that reduced O2 so it doesn’t kill it and produce hydrogen peroxide which
are toxic, powerful oxidizing agents that destroy cellular structures very rapidly. To
protect against toxic O2 products, obligate aerobes and facultative anaerobes usually
contain the enzyme superoxide dismutase that catalyzes the destruction of superoxide and
either catalase or peroxidase. Bm and Erc produced growth and H2O2 by forming
bubbles of oxygen unlike Ec that showed no growth or H2O2 with no bubbles being
produced so it cant produce enzymes to protect itself against O2 products.
Pg. 9
10. The Casein Plate is a large milk protein incapable of permeating the plasma
membrane of bacteria which is the main reason why milk is white but it first must be
degraded into amino acids. Some bacteria can secrete proteases that catalyze the
hydrolysis (proteolysis) of casein to yield amino acids and then are transported into the
cell and catabolized. All of the bacteria (Ec, Bm, Erc) produced growth but only Erc had
a zone of hydrolysis that is indicated by a clear area surrounding the colony where the
hydrolytic reaction yields soluble amino acids. Bm and Ec had no protease activity and
the colony remained opaque.
The Starch Plate test was used to see if bacteria could hydrolysis starch after
adding Garm’s Iodine. Hydrolases catalyze the splitting of organic molecules into smaller
ones in the presence of water. All of the bacteria (Ec, Pv, Bm) produced growth and only
Bm formed a blue to brown comlplex when iodine was added that showed it hydrolyzed
starch. Ec and Pv remained clear after the iodine was added indicating that the alpha-
amylase was produced by the bacteria and no starch was hydrolyzed.
The Enterotube II System was consisted of a single tube that contained 12
compartments of different solid agar medium with compartments that required some
aerobic conditions to have small openings. This was used to help identify the unknown
bacteria #9 and what properties it consisted of. The ID biocode was 30400 which
indicated that there was gas production from glucose so it can fermentate it, couldn’t
produce H2S but could hydrolyze tryptophan, negative for VP so it didn’t produce
acetoin as well as no production of urease and citrate. With these results, it can be
concluded that the unknown bacteria #9 was Ec.
The API 20E System is a standardized mini biochemical identification tool for
Enterobacteriaceae and other gram-negative bacteria. There are 20 chambers with
cupules consisting of dehydrated substrates and anaerobic conditions are formed with the
addition of sterile mineral oil. The Profile index number was 3442731 which indicated
that beta-galactosidase was hydrolyzed (ONPG) and ornithine, ammonia, carbon dioxide
was produced (ADH), hydrogen sulfide was produced (H2S), gelatin was liquefied by
proteolytic enzymes (GEL), acid formation occurred from Mannitol (MAN), Inositol
(INO), Sorbitol (SOR), Rhamnose (RHA), Sucrose (SAC) and Amygdalin (AMY) which
catalase releases from oxygen gas from hydrogen peroxide. With these results the
unknown bacteria #9 can’t be Ec because it shouldn’t produce H2S. Comparing the 2
tests, it can be concluded that the unknown bacteria was something not used from the
ones listed or there was an error in validating the results.
VI. References
Harley, J. Laboratory Exercises in Microbiology. Fifth Edition (2010)
Pg. 10