This slide will explain how to identify unknown bacteria in a laboratory..

1. Classification of microorganisms
Presented by
R.Parthasarathy

2. INTRODUCTION:
Classification of organism.
Difference between the bacteria, archaea,
Eukarya.
Fungi, Alagae, Protozoa, Virus, Bacteria.
Identification of bacteria.
General characteristics features used for
classification of bacteria.

3. BINOMINAL NOMENCLATURE:
In the 18th century, Carolus Linnaeus, a Swedish scientist,
began identifying living organisms according to similarities in
resemblances and placing organisms in one of two
“kingdoms”
Vegetalia and Animalia.
Genera named after individuals:
Escherichia coli: Theodore escherich invented the bacteria
which causes disease in colon.
Neisseria gonorrhoea: Albert Neisser discovered the bacteria
which causes gonorrhoea.

4. Binominal nomenclature: cont..
Genera named after Microbe’s shape:
Vibrio chlerae:
Bacteria is comma shaped which causes cholera.
Staphyococcus epidermidis:
Staphylo means clusters; coccus means spheres.
Genera named after Attribute of the Microbe:
Saccharomyces cerevisiae:
Saccharo means sugar; Myces means fungus; cerevisiae means
beer. Bacteria which converts sugar in the sample into Alcohol.

5. Five Kingdom System

6. WOESE’S THREE-DOMAIN SYSTEM:
In Woese’s three-domain system, one branch of the phylogenetic tree includes the
former archaebacteria and is called the domain Archaea ( FIGURE ). The second
encompasses all the remaining true bacteria and is called the domain Bacteria. The third
domain, the Eukarya,includes the four remaining kingdoms (Protista, Plantae, Fungi, and
Animalia).

8. FUNGI
• Fungi exist in either yeast or mold forms.
• The smallest of yeasts are similar in size to bacteria, but most are larger (2 to 12
m) and multiply by budding.
• Molds form tubular extensions called hyphae, which, when linked together in a
branched network, form the fuzzy structure seen on neglected, bread.
• Fungi are eukaryotic, and both yeasts and molds have a rigid external cell wall
composed of their own unique polymers, called glucan, mannan, and chitin.
• Their genome may exist in a diploid or haploid state and replicate by meiosis or
simple mitosis.
• Most fungi are free-living and widely distributed in nature.
• Generally, fungi grow more slowly than bacteria, although their growth rates
sometimes overlap.
• The fungi probably represent an evolutionary offshoot of the protozoa; they are
unrelated to the actinomycetes, mycelial bacteria that they superficially
resemble.
• The major subdivisions (phyla) of fungi are: Chytridiomycota, Zygomycota (the
zygomycetes), Ascomycota (the ascomycetes), Basidiomycota (the
basidiomycetes), and the "deuteromycetes" (or imperfect fungi).

10. ALGAE
• The term "algae" has long been used to denote all organisms that produce O2 as a
product of photosynthesis.
• One major subgroup of these organisms—the blue-green bacteria, or
cyanobacteria—are prokaryotic and no longer are termed algae.
• This classification is reserved exclusively for photosynthetic eukaryotic organisms.
• All algae contain chlorophyll in the photosynthetic membrane of their subcellular
chloroplast.
• Many algal species are unicellular microorganisms. Other algae may form
extremely large multicellular structures.
• Kelps of brown algae sometimes are several hundred meters in length.
• A number of algae produce toxins that are poisonous to humans and other animals.
• Dinoflagellates, a unicellular algae, cause algal blooms, or red tides, in the ocean.
Red tides caused by the dinoflagellate Gonyaulax species are serious as this
organism produces neurotoxins such as saxitoxin and gonyautoxins, which
accumulate in shellfish (eg, clams, mussels, scallops, and oysters) that feed on this
organism.
• Ingestion of these shellfish by humans results in symptoms of paralytic shellfish
poisoning and can lead to death.

11. PROTOZOA
• Protozoa are unicellular nonphotosynthetic protists.
• The most primitive protozoa appear to be flagellated forms that in
many respects resemble representatives of the algae.
• It seems likely that the ancestors of these protozoa were algae that
became heterotrophs—the nutritional requirements of such
organisms are met by organic compounds. Adaptation to a
heterotrophic mode of life was sometimes accompanied by loss of
chloroplasts, and algae thus gave rise to the closely related protozoa.
• From flagellated protozoa appear to have evolved the ameboid and
the ciliated types; intermediate forms are known that have flagella at
one stage in the life cycle and pseudopodia (characteristic of the
ameba) at another stage.
• A fourth major group of protozoa, the sporozoa, are strict parasites
that are usually immobile; most of which reproduce sexually and
asexually in alternate generations by means of spores.

12. VIRUS
• Viruses are strict intracellular parasites of other living cells, not only of
mammalian and plant cells, but also of simple unicellular organisms,
including bacteria (the bacteriophages).
• Viruses are simple forms of replicating, biologically active particles that carry
genetic information in either DNA or RNA molecules enclosed in a protein
coat or capsid.
• Proteins—frequently glycoproteins—in the capsid determine the specificity of
interaction of a virus with its host cell.
• The capsid protects the nucleic acid and facilitates attachment and
penetration of the host cell by the virus.
• Inside the cell, viral nucleic acid redirects the host's enzymatic machinery to
functions associated with replication of the virus. In some cases, genetic
information from the virus can be incorporated as DNA into a host
chromosome.
• In other instances, the viral genetic information can serve as a basis for
cellular manufacture and release of copies of the virus. This process calls for
replication of the viral nucleic acid and production of specific viral proteins.

13. BACTERIA
• Bacteria are the smallest (0.1 to 10 m) living cells.
• They have a cytoplasmic membrane surrounded by a cell wall; a unique
interlinking polymer called peptidoglycan makes the wall rigid.
• The simple prokaryotic cell plan includes no mitochondria, lysosomes,
endoplasmic reticulum, or other organelles .
• In fact, most bacteria are about the size of mitochondria.
• Their cytoplasm contains only ribosomes and a single, double-stranded
DNA chromosome.
• Bacteria have no nucleus, but all the chemical elements of nucleic acid
and protein synthesis are present.
• Although their nutritional requirements vary greatly, most bacteria are
free-living if given an appropriate energy source.
• They divide by binary fission and can be grown in artificial culture, often
in less than 1 day.
• Archaebacteria differ radically from other bacteria in structure and
metabolic processes; they live in environments humans consider hostile
(eg, hot springs, high salt areas) but are not associated with disease.

14. IDENTIFICATION OF BACTERIA
Biochemical Tests
• A large number of biochemical tests exist and often a specific test can
be used to eliminate certain groups from the identification process.
• Among the more common tests are: fermentation of carbohydrates,
the use of a specific substrate, and the production of specific products
or waste products. But, as with the physical characteristics, often
several biochemical tests are needed to differentiate between
species.

16. SEROLOGICAL TESTS
• Microorganisms are antigenic, meaning they are capable of triggering the
production of antibodies.
• Solutions ofsuch collected antibodies, called antisera, are commercially
available for many medically important pathogens. For example, mixing
a Salmonella antiserum with Salmonella cells will cause the cells to clump
together or agglutinate. If a foodborne illness occurs, the antiserum may
be useful in identifying if Salmonella is the pathogen.
• In recent years, a number of miniaturized systems have been made
available to microbiologists for the rapid identification of enteric bacteria.
• One such system is the Enterotube II, a self-contained, sterile,
compartmentalized plastic tube containing 12 different media and an
enclosed inoculating wire. This system permits the inoculation of all media
and the performance of 15 standard biochemical tests using a single
bacterial colony. The media in the tube indicate by color change whether
the organism can carry out the metabolic reaction. After 24 hours of
incubation, the positive tests are circled and all the circled numbers in
each boxed section are added to yield a 5-digit ID for the organism being
tested. This 5-digit number is looked up in a reference book or computer
software to determine the identity of the bacterium.

19. Thank you