The document discusses the nutrition and cultivation of microorganisms. It describes that microorganisms require carbon, nitrogen, inorganic ions, essential metabolites, and water as nutrients. The document classifies microorganisms based on their carbon and energy sources into four groups: chemoautotrophs, chemoheterotrophs, photoautotrophs, and photoheterotrophs. It also discusses different types of media used for cultivating microorganisms, including chemically defined and complex media made from natural products. The document provides examples of media compositions for growing bacteria, fungi, protozoa, and algae.

1. Nutrition and Cultivation of
Microorganisms

2. Bacterial Nutrition

3. Nutrition
- the kind of food used and the methods by which it is
assimilated and utilized
Two-fold purpose:
1. to synthesize (build up) protoplasm
2. to supply energy for all life processes
Microorganisms require nutrients like:
1. Carbon source
a. Heterotrophs- microbes that used organic cpds
as major source of C
- obtain such organic molecules
by absorbing them from the environment, or
by ingesting autotrophs or other heterotrophs
b. Autotrophs- microbes that used carbon dioxide (most
oxidized form of carbon) as their major or even
sole source of carbon

4. -can live exclusively on relatively simple inorganic
molecules and ions absorbed from the environment
2. Nitrogen Source
3. Certain inorganic ions
4. Essential metabolites (vitamins; possibly amino acids)
5. Water
*Differences between the nutrition of animals and that of bacteria
1. Holozoic nutrition –wherein solid food is ingested by the
organism (eg. Typical of animals and protozoa)
2. Holophytic – bacteria cannot ingest solid food as well as
true fungi so they must receive their nutrients in a
solution of water, which means digestion must take
place outside the organism.

5. Some nutrients, called MACRONUTRIENTS, are
required in large amounts, like C, H, N, O
- needed by cell but in small amounts (P, S, K,Mg,
Ca, Na)
while others MICRONUTRIENTS, are required in just trace
amounts. - Iron and Other Trace Metals
*siderophores –produce by cell as iron-binding
molecules
- function to bind Fe3+ and transport
it into the cell. A major group of
siderophores is the hydroxamic
acids, organic molecules that
chelate Fe3+ strongly.

8. Type Function Examples
Carbon Source Provides energy through
oxidation and provides the
structural components of
the cell wall
May include virtually any
carbon containing
compound; varies from CO2
in the air to very complex
organic substances
Nitrogen Source Provides nitrogen for the
synthesis of amino acids,
nucleic acids and coenzymes
Some species use N2 of air,
others inorganic compounds
such as NO3
- or NH4
+; others
require organic sources of
nitrogen such as glutamine
or asparagine
Inorganic ions Necessary cofactors for
enzymes; storage of energy;
electron transport system
Mg2+, Mn2+, Fe2+, PO4
2-, Na+,
K+ and even Mo for
organisms fixing gaseous
nitrogen
Essential metabolites To provide complex organic
compounds which an
organism is unable to
synthesize
Vitamins, amino acids,
purines, pyrimidines,
coenzymes, heme
Table 4 Summary of Bacterial Nutrients

9. Nutritional Classification of Microorganisms
Chemotrophs – organisms that use chemical compounds for energy
Autotrophs - organisms that depend primarily on radiant energy
(light)
*by combining these terms with those of C sources, the following
groupings emerge
1. Chemoautotrophs – organisms use chemical substances (inorganic)
as source of energy + carbon dioxide as the main source of
carbon
2. Chemoheterotrophs- organisms that use chemical substance
(organic) as source of energy + organic compounds as the
main source of carbon
3. Photoautotrophs – organisms that use light (E source) + CO2 (carbon
source)
4. Photoheterotrophs- organisms use light (E source)+ organic cpds
(carbon source)

10. Nutritional Group Carbon source Energy source Examples
Chemoautotrophs Carbon dioxide Inorganic
compounds
Nitrifying, hydrogen,
iron and sulfur
bacteria
Chemoheterotrophs Organic compounds Organic compounds Most bacteria, fungi,
protozoa and
animals
Photoautotrophs Carbon dioxide Light Purple sulfur and
Green sulfur
bacteria, algae,
cyanobacteria and
plants
Photoheterotrophs Organic compounds light Purple nonsulfur and
green nonsulfur
bacteria
Table 4.1 Nutritional Classification of Bacteria and other organisms

12. *some species of microorganisms are versatile in their
nutritional needs; they cannot be categorized exclusively
into one of the four groupings (eg. Certain phototrophic
bacteria can also grow as chemotrophs)
in the absence of oxygen (anaerobic conditions),
Rhodospirillum rubrum depends on light as its energy
source and lives a photoheterotrophs but in the presence
of oxygen (aerobic conditions), it can grow in the dark as a
chemoheterotroph

13. *one organism can help another to grow
-when 1 organism produces a waste product that
another organism uses as food (eg. The good relationship
of three species of bacteria- Streptococcus thermophilus,
Lactobacillus bulgaricus, and
Propionibacterium shermanii –used in the manufacture of
Swiss cheese; strptococci and lactobacilli ferment the
lactose in milk and produce the lactic acid as waste
product and the propionibacteria can then grow on lactic
acid to produce propionic acid as their waste which gives
the characteristic nutlike flavor of Swiss cheese

14. -Two organisms can benefit equally when each makes an
essential nutrient required by the other (Bacillus polymyxa
and Proteus vulgaricus will not grow in lab culture
medium lacking the vitamins niacin and biotin but they
can grow together in such medium as a mixed culture
because B. polymyxa makes the niacin required by the P.
vulgaricus and P. vulgaricus makes the biotin needed by
the B. polymyxa)
-relationship between the bacteria rhizobia and
leguminous plants

33. Media usedfor cultivating microorganisms
Chemically defined media
-used to determine the precise nutritional requirements of a
microorganism
Bacterial strain 2 –prototrophic
(it does not require organic
supplements since it can
grow on the minimal
medium plate “control”)
Bacterial strains 1 & 3-
auxotrophic (need organic
supplements in the minimal
medium before they can
grow (no growth on the
“control” plate)
*Control medium has glucose
and salts only

34. Biosynthesis of tryptophan:
Minimal medium anthranilic acid indole tryptophan
ingredients
A B C
For routine lab cultivation abc study of heterotrophs, complex culture media
prepared from natural products are used, such media are chemically undefined.
Examples of natural products added to media include:
1. Meat extract(an aqueous beef extract concentrated to a paste)
2. peptone (proteins that have been partially degraded by enzymes,
milk-casein hydrolysate and soybean-protein hydrolysate)
3. yeast extract
4. blood serum
5. milk
6. soil extract
7. bovine rumen fluid
*there are media that are commercially available

36. Fig 4. Different commercially prepared agar media in Petri dishes
are shown streaked with bacteria to obtain isolated colonies

37. API 20E System
-for identification
of bacteria in the
Enterobacteriaceae
family and Gram- bacteria
0.85% NaCl Saline suspension of
E. coli cells

39. Media for the Growth of Bacteria
A. Chemically defined medium for a chemoautotrophic bacterium
Ingredient Function Amount
(NH4)2SO4 Nitrogen as well as energy
source
0.5 g
NaHCO3 Carbon source in the form of
CO2 in aqueous solution
0.5 g
Na2HPO4 Buffer and essential ions 13.5 g
KH2PO4 Buffer and essential ions 0.7 g
MgSO4.7H2O Essential ions 0.1 g
FeCl.6H2O Essential ions 0.014 g
CaCl2.2H2O Essential ions 0.18 g
water Solvent 1000 ml

40. The 3M™ Petrifilm™ E.coli/Coliform Count
Plate identifies both E. coli and other coliforms
with confirmed results in just 24-48 hours.

41. 3M™ Petrifilm™ Aerobic Count Plates

42. B. Chemically Defined Medium for a Heterotrophic bacterium
Ingredient Function Amount
Glucose Carbon and energy source 1 g
NH4H2PO4 Nitrogen source, buffer
and essential ions
5 g
K2HPO4 Buffer and essential ions 1 g
NaCl Essential ions 5 g
MgSO4.7H2O Essential ions 0.2 g
water solvent 1000 ml
*The above ingredients represent the minimum constituents in a medium for a
nonfastidious bacterium such as the wildtype E. coli. For a fastidious species
such as Lactobacillus acidophilus, additional substances such as amino acids and
vitamins have to be added to the medium

43. Solid and Liquid Culture Media

44. C. Composition of Nutrient Broth, a complex medium for the growth
of heterotrophic bacteria
Ingredient Function Amount
Beef extract Water-soluble substances of
animal tissue;
carbohydrates, organic
nitrogen compounds,
vitamins, salts
3 g
Peptone Organic nitrogen 5 g
Sodium chloride Ions and osmotic
requirements
8 g
Water solvent 1000 ml
•If a solid medium is required, agar (15 g) is added, the
medium is then called nutrient agar

46. Media for the Growth of Fungi
- Have higher sugar concentration (4%) and a lower pH range(3.8 to 5.6) than media
For bacterial growth which is generally pH 6.5 to 7.5.
D. Composition of a General Purpose Medium, Sabouraud’s Agar for the isolation and
growth of fungi
Ingredient Function Amount
Peptone Source of Carbon, nitrogen
elements
10 g
Glucose Carbon and energy source;
high concentration favors
growth of fungi but inhibits
growth of bacteria
40 g
Agar Solidifying agent 15 g
water solvent 1000 ml
pH Low pH suppresses bacterial
growth but enhances fungal
growth
5.6

48. Media for the Growth of the Protozoa
-have pH range of 6 to 8 for optimal growth
-protozoa are aerobic heterotrophs with complex nutritional requirements
Media for the Growth of Algae
- algae use light for energy and require only carbon dioxide, water and various
soluble inorganic ions for growth (they are photoautotrophs)
-some undefined media for algae usually contain supplements such as soil
extract, a rich source of nutrients
Other types
1. Special-Purpose media
-when microbiologists want to isolate, identify or count microbes
a. Media for Anaerobes
anaerobes( organisms that tolerate little or no oxygen and do not
use oxygen to obtain energy)
-for years, anaerobic bacteria were grown in agar medium deeps
or media in tall test tubes(bacteria could grow in the bottom of these tubes
bec. the top layer of agar excluded atmospheric O2; other refinements
included the addition of Sodium thioglycolate

49. Tube 1 = strict aerobe
Tube 2 = facultative
Tube 3 = aerotolerant
Tube 4 = strict anaerobe

52. Sodium thioglycolate –reducing agent (that would remove oxygen to make
what we called reduced media)
2. Selective media
- are designed to enhance the growth of particular kind of microorganism
or suppress the growth of other kinds of microorganisms
(some may do both)
eg. Sabouraud’s agar
3. Differential Media
-microbiologists use differential media when they want to differentiate
among various kinds of microorganisms on an agar plate
4. Selective/Differential
-some culture media are both selective and differential.
eg. MacConkey agar which contains bile salt and crystal violet dye to inhibit
the growth of Gram+ bacteria and allow Gram_ bacteria to grow
5. Enrichment Media
-when a species of special interest are present but only in very small
numbers, microbiologists use this medium. The medium favors the growth

53. of that species, but not the growth of the others present in the mixed population
MacConkey’s agar
-Selective for gram negative
Bacteria (growth of G+ is inhi-
bited by the crystal violet dye
& bile salts in the media)
-differential for lactose fer-
mentation(neutral red pH
indicator turns red in the
presence of acid by-products
of lactose fermentation)

54. Microbiological Assay Media
- specific microorganisms can be used to measure the concentrations of
Substances such as antibiotics and vitamins
-blood serum or other tissue fluids can be assayed for antibiotics by using
Microorganisms known to be susceptible to those antibiotics. This type of assay
Involves the measurement of growth inhibition caused by antibiotic.
Tissue Culture Media and Methods
Tissue cultures are plant or animal cells grown in the lab in specialized
media
-methods were developed to cultivate viruses in vitro

70. Bacillus subtilis
gram positive, sporeforming rods
produce colonies which are dry,
flat, and irregular, with lobate
margins.
Circular, pinhead colonies which are convex
with entire margins. This gram positive coccus
often produces colonies which have a golden-
brown color.
Staphylococcus aureus.

71. Micrococcus luteus. Circular, pinhead colonies which are convex with entire margins. This gram
positive coccus produces a bright yellow, non-diffusable pigment.
Rhodospirillum rubrum. Pinpoint circular colonies which are convex with entire margins. This gram
negative spirillum produces a non-diffusable red pigment.
Serratia marcescens. These gram negative rods produce mucoid colonies which have entire margins
and umbonate elevation. Note that there are both red and white colonies present on this
plate. Some strains of S. marcescens produce the red pigment prodigiosin in response to incubation
at 30o C, but do not do so at 37o C. This is an example of temperature-regulated phenotypic
expression.

72. Escherichia coli. This gram negative rod (coccobacillus) forms shiny, mucoid colonies which have entire margins and
are slightly raised. Older colonies often have a darker center.
Enterobacter aerogenes. This gram negative rod is a common contaminant of vegetable matter which forms shiny
colonies with entire margins and convex elevation.

116. Thank you for listening!