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Classification of bacteria

PREPARED BY:

DEBASHIS DASGUPTA



CLASSIFICATION AND IDENTIFICATION

OF BACTERIA

Classification seeks to describe the diversity of bacterial species by naming

and grouping organisms based on similarities.

Bacteria can be classified on the basis of cell structure ,cellular metabolism

or on differences in cell components such as DNA, fatty acids ,pigments

,antigens and quinones

Modern bacterial classification emphasizes molecular systematics, using genetic

techniques such as GUANINE – CYTOSINE ratio determination , GENOME-

GENOME hybridisation.

Classification of bacteria is determined by publication in the International

Journal of Systematic Bacteriology and BERGEY’S manual of systematic

bacteriology. The International Committee on systematic bacteriology

maintains international rules for the naming of bacteria and taxonomic

categories and for their ranking in the INTERNATIONAL CODE OF

NOMENCLATURE OF BACTERIA.

Continued





The need to identify human pathogens is the major impetus for thedevelopment of techniques to classify bacteria.

Specific group of bacteria is responsible for stabilisation of specificgroups of wastes. Proper classification and idea about each group isessential for biodegradable waste stabilisation.

Following taxonomic identifications enumeration and evaluation of thecharacteristics of the various organisms and structures present in a wastewater sample ,the inforamation can be used to draw conclusionsregarding the treatment process .

Bacteria play an important role in many technological fields e.g.medicine , sewage control etc. The overall commercial worth of bacteria in these operations is immense. Classification categorizes different types of bacteria and provides a way to choose the most suitable bacteria typefrom technical and industrial point of view.

continued



CHARACTERS

GRAM STAINING

REACTIONS

NUTRITIONAL ANDBIOCHEMICAL

CHARACTERISTICS

COLONY MORPHOLOGY

BACTERIOPHAGE

TYPING

GENETIC METHODS IN

TAXONOMY

r-RNA CATALOGUING

GAS

CHROMATOGRAPHY

USES OF COMPUTER

continued



GRAM STAINING::BACTERIA can be

classified into two major groups suchas GRAM POSITIVE and GRAMNEGATIVE bacteria based on GRAMSTAINING REACTION. This empiricaltechnique is used to differentiatebacteria based on the physicalproperties of the cell wall .

. NUTRITIONAL AND BIOCHEMICALCHARACTERISTICS:The most commonlyused biochemical tests include abilityto utilize various sugars, productionof acids and/or gas when grown insugar media (which can be detectedby a change in the colour of anIndicator),ability to produce indole,hydrogen sulfide etc. The presence of certain enzymes in growth mediasuch as catalase , gelatinase , urease ,lecthinase or lipase are frequentlyused in identification of bacteria.

continued



COLONY MORPHOLOGY::Bacteria show

characteristic type of growth on solid

media under appropriate culturalconditions and the colony morphology can

be used in presumptive identification .

BACTERIOPHAGE TYPING:This method is

used for typing bacteria by testing thesusceptibility of the culture to lysis by

each of a set of type ,lytic

bacteriophages .

continued



GENETIC METHODS IN TAXONOMY In recent years,

the genetic characterisation of organisms has been

substantially developed . One is the analysis of the base

composition of DNA i.e. to determine the mole %

GUANINE and CYTOSINE in DNA %(G+C) . The

second is to determine the degree of similarity between twoDNA samples by hybridization between DNA&DNA or

DNA&RNA.

r-RNA-CATALOGUING: Over the past decade, comparative

analysis of the 16-s rRNA sequences has been used to

explore prokaryotic phylogeny.

GAS-CHROMATOGRAPHY: In addition to the use of

chemical, physical and physiological characteristics of

bacteria ,GAS-CHROMATOGRAPHY in recent years has also

been used to detect specific cellular components in

bacteria and for rapidly identifying bacteria.

COMPUTER IN BACTERIAL IDENTIFICATION AND

CLASSIFICATION: In recent years , the computer has been

used as an aid in grouping bacteria and classifying them

with a great degree of precision.

continued



1. ALKALIPHILIC 10.OLIGOTROPHIC

2.CAPNOPHILIC 11.OSMOPHILIC

3.ENDOLITHIC 12.PSYCHROPHILIC

4.HYPERTHERMOPHILIC 13.RADIORESISTANT

5.THERMOPHILIC 14.XEROPHILIC

6.HYPOLITHIC 15.HALOPHILIC

7.LIPOPHILIC 16.ACIDOPHILIC

8.METALOTOLERANT 17.BAROPHILIC

9.MESOPHILIC

continued



ALKALIPHILIC BACTERIA : The term alkaliphileis used for microrganisms that growoptimally or very well at pH values above9, often between 10 and 12, but cannotgrow or grow only slowly at the near

neutral pH value of 6.5. Internal pHmaintenance is achieved by both activeand passive mechanisms in alkaliphilicbacteria .

CAPNOPHILIC BACTERIA:Capnophiles areextremophile microrganisms which thrive inthe presence of high concentration of CO2or which require the presence of CO2 tosurvive.One example of a capnophile is thegram – negative Aggregatibacter sp. foundin the mouth .

ENDOLITHIC BACTERIA:An endolith is anorganism that lives inside the rock ,coral ,animal cells or in the pores between themineral grains of a rock. The microbiotopewhere these different endolithic specieslive together is called SLIME.

ALKALIPHILIC

ENDOLITHIC

continued



HYPERTHERMOPHILIC BACTERIA:Ahyperthermoph-ile is an organism that thrivesin extremely hot environments from 60: Cupwards . Optimal temperature being 80: C.Hyperthermophiles are mainly within the

domain archaea although some bacteria arealso able to tolerate temperatures of around100: C.

THERMOPHILIC BACTERIA: A thermophile is an

organism that thrives at relatively hightemperature . The order THERMOTOGALESforms a special class among bacteria as beingthe most thermophilic bacteria known atpresent .

HYPOLITHIC BACTERIA: In arctic and antacticecology an hypholith is a photosyntheticorganism that lives underneath rocks inclimatically extreme deserts . About 94-95% of 850 opaque dolomitic rock samples of devonisland were colonized by hypoliths ,dominated chiefly by CYANOBACTERIA .

HYPERTHERMOPHILIC

HYPOLITHIC continued



LIPOPHILIC BACTERIA: Liphophilic bacteria are

bacteria that may proliferate in lipids. They

include lipophilic Corynebacterium .

METALOTOLERANT BACTERIA:These are organisms

capable of tolerating high levels of dissolved

heavy metals in solutions like cadmium , zinc,copper, silver. Example-Flavobacterium .

MESOPHILIC BACTERIA : Bacterial species involved

in biodegradation which are more active in

temperatures ranging from approximately 70:-90:F are termed mesophilic bacteria.

EXAMPLE-Streptococcus pyrogenes .

BACILLUS LICHENIFORMIS

FLAVOBACTERIUM

continued



OLIGOTROPHIC BACTERIA:An oligotroph is an

organism that can live in an environment that

offers very low levels of nutrients.Pelagibacter

eubique is the most abundant oligotrophic

bacteria in the oceans with an estimated 10^27

individuals in total .

OSMOPHILIC BACTERIA:These are bacteria that

can withstand high osmotic pressure like high

sugar concentration . They are characterized by

low water activity . EXAMPLE-Enterobacter

aerrogenes.

PSYCHROPHILIC BACTERIA:Psychrophilic bacteria

utilise a wide variety of metabolic pathways

including photosynthesis , chemoautotrophy and

heterotrophy and form diverse communities . They

are characterized by lipids and membranes

chemically resistant to the stiffening caused by

extreme cold .EXAMPLE-Psychrobacter Sp.

OSMOPHILIC

BACTERIA

continued



RADIORESISTANT BACTERIA: . Deinococcus

radiodurans is a highly radioresistant bacterium

which can be used to precipitate out uranium

from radioactive wastes and also to detoxify

mercury and toluene in radioactive wastes . .Deinococcus radiodurans has been listed as the

world’s toughest bacterium in the Guiness

book of world record’s. It is extremely resistant

to ionizing radiation , UV rays , desiccation ,

oxidizing and electrophilic agents.

XEROPHILIC BACTERIA: Xerophiles are extre-

mophilic organisms that can grow and

reproduce in conditions with a low availability

of water , also known as water activity. . The

common food preservation method of reducing

water activities may not prevent the growth of

xerophilic bacteria , often resulting in food

spoilage .

continued

Deinococcus

radiodurans

XEROPHILIC

BACTERIA



HALOPHILIC BACTERIA: Halophiles are extremophile

organisms that thrive in environments with very

high concentrations of salt .

ACIDOPHILIC BACTERIA : Acidophiles are organisms

that can withstand and even thrive in acidic

environments where the pH values range from 1-5

Normally high acid levels destroy cells . EXAMPLE- T .

acidophilus .

BAROPHILIC BACTERIA: Many microrganisms from the

deep -sea display high-pressure-adapted - also

described as barophilic or piezophilic growth

characteristics. A large proportion of the barophilic

bacteria currently in culture collections belong to a

distinct subgroup of the genus Shewanella referred

to as the barophile branch .EXAMPLE- Moritella

yayanosii .

continued





AEROBICBACTERIA

OBLIGATE AEROBES

FACULTATIVE

ANAEROBES

MICROAEROPHILES

ANAEROBICBACTERIA

OBLIGATEANAEROBES

FACULTATIVE

ANAEROBES

AEROTOLERANTANAEROBES

BACTERIA

continued



MYCOBACTERIUM TUBERCULOSIS –

AN AEROBIC BACTERIA.

E.COLI –A FACULTATIVE ANAEROBIC

BACTERIA.

CLOSTRIDIUM TETANI- ANANAEROBIC BACTERIA.

continued





COCCUS

DIPLOCOCI

TETRACOCCI

STAPHYLOCOCCI

SARCINAE

BACILLUS

DIPLOBACILLI

STREPTOBACILLI

SPIRILLA VIBRIOS

BACTERIA

continued





*

HETEROTROPHIC

SAPROPHYTIC

SYMBIOTIC

PARASITIC

AUTOTROPHIC

PHOTOSYNTHETIC

CHEMOAUTOTROPHIC

**(DETAILED CLASSIFICATION ON NEXT

SLIDE)

BACTERIA

continued



IRON BACTERIA

SULPHUR BACTERIA

HYDROGEN BACTERIAMETHANE BACTERIA

CO2 FIXING BACTERIA

CO FIXING BACTERIA

N2 FIXING BACTERIA

AMMONIFYING BACTERIA

CHEMOAUTROPHIC

BACTERIA

continued

(**)





FLAGELLA : Flagella arises from the basal granules just inside the plasma membraneThey contain a single kind of protein known as flagellin . On the basis of thenumber of flagella and their arrangement , the following types of bacteria arerecognised :

Atrichous : Bacteria without flagella .e.g. Corynaebacterium diptheriae .

Monotrichous : Bacteria with single flagellum situated at one end of the cell only.e.g. Vibrio choleri.

Lophotrichous :Bacteria with a group of flagella at one end of the cell only. e.g.Pseudomonas aeruginosa.

Amphitrichous : Bacteria with one flagellum or more than one flagella at two endsof the cell. e.g. Spirillum volutans.

Peritrichous : Bacteria with flagella all over the cell. e.g . Bacillus subtilis.

continued



GENETICALLY MODIFIED BACTERIA :

• 1.CREATING ANTI-CANCER VACCINE : An experimentalcancer vaccine using defanged listeria bacteria isshowing great promise in animal studies .

•

2. MAKING GASOLINE FROM BACTERIA : Nowadaysresearches are being made to produce variousgenetically engineered bacteria (E.coli.) to custom – produce hydrocarbon chains which can be made intofuel .

•

3.PREVENTING DENTAL CAVITIES : Genetically modifiedbacteria BCS3-L1 could theoretically prevent dentalcavities by colonizing mouth.

A NEW OUTLOOK :GENETICALLY MODIFIED

BACTERIA (GENE CLONING)

continued





Oxidation Ponds - Oxidation ponds or stabilisation ponds and lagoons are used for

simple secondary treatment in rural areas or industrial units. Heterotrophic

bacteria degrade sewage organic matter within ponds produced cellular material

and mineral products that support the growth of algae.Oxygen produced by algaecompensate for the poor O2 conditions created by heterotrophic bacteria.

Activated Sludge Process - Various microorganisms are involved in the activated

sludge process. The most important one is the rod shaped bacterium, Zoogloea

ramigera This organism is the main agent for flocculation.Among other bacterial

forms the major genera are Pseudomonas, Nitrosomonas,Flavobacterium,

Alcaligenes, Brevibacterium, Bacillus, Beggiatoa, Achromobacter etc.

Anaerobic Sludge Digestion - Various physiological groups of bacteria occur in

anaerobic sludge digestion tank. There are three different groups of bacteria

occurring in this process: hydrolytic, fermentative and methanogenic bacteria.However, there is some overlap between the members of the first two groups.

continued



Oxidation pond, in which both aerobic and anaerobic activities arecarried out in a single unit is called facultative pond. They are the most

widely used oxidation ponds.

continued



Bacteria is one of the major equipments inmedical , clinical, and environmentalmicrobiology.

It is a major tool in biological treatmentprocesses.It is used for propermanagement of liquid and solid wastes.

Classification of bacteria remains a field of growing awareness due to the rapidprogress of bacteriology ,wastewaterengineering and the future prospect of

environmental biochemistry.

CONCLUSION



REFERENCES

• http://mic.sgmjornal.org/cgi/content/full/146

/3/5/51

• Deming J W & Baross J A

Applied environmental microbiology

• http://serc.carleton.edu/microlife



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