Bacteria | CEE Academy

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HISTORY

Table 1: Bacteria: Historical Points

Point	Scientist / Detail
First observation of bacteria / animalcules	Antonie van Leeuwenhoek
Term 'Bacterium'	Christian Gottfried Ehrenberg
Bacteria classified under Schizomycetes	Carl Nägeli
Bacteria placed under genus Vermes	Carl Linnaeus
Bacteria placed in kingdom Monera	H. F. Copeland
Germ theory of disease + pasteurization	Louis Pasteur
Causative agent of tuberculosis + Koch's postulates	Robert Koch
Antiseptic surgery; carbolic acid / phenol	Joseph Lister
Transformation	Frederick Griffith
Conjugation	Joshua Lederberg + Edward Tatum
Transduction	Norton Zinder + Joshua Lederberg

Important Titles

❖ Father of Microscopy: Antonie van Leeuwenhoek

❖ Father of Bacteriology: Robert Koch

❖ Father of Microbiology: Louis Pasteur

❖ Father of Antiseptic Surgery: Joseph Lister

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GENERAL FEATURES

▢ Definition: Bacteria = unicellular prokaryotic microorganisms belonging to domain Bacteria

▢ Core Characters:

•
Ubiquitous → soil, water, air, organisms, extreme habitats
•
Usually 0.5–5 µm
•
No true nucleus or membrane-bound organelles
•
DNA + RNA both present
•
Usually single circular double-stranded chromosome in nucleoid
•
70S ribosomes = 50S + 30S
•
Cell wall usually contains peptidoglycan
•
Reproduction mainly by binary fission
•
Mostly heterotrophic; some autotrophic
•
Reserve food → glycogen, poly-β-hydroxybutyrate / PHB, polyphosphate
•
Important decomposers + mineralizers

Exceptions

❖ Cell wall absent: Mycoplasma

❖ Peptidoglycan absent: Archaea

❖ Multiple / linear chromosomes: Present in some bacteria

❖ Photosynthesis: Present in cyanobacteria and photosynthetic bacteria

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CHARACTERISTIC FEATURES

▢ Genetic Material:

•
DNA + RNA both present
•
Chromosome located in nucleoid / genophore / nuclear equivalent
•
Usually haploid, circular, double-stranded DNA
•
Histone proteins absent in most true bacteria
•
Extra-chromosomal DNA may occur as plasmids

▢ Cell Wall Sugars:

•
N-acetylglucosamine / NAG
•
N-acetylmuramic acid / NAM
•
Alternating NAG–NAM chains cross-linked by short peptides

▢ Ribosome: 70S ribosome = 50S + 30S

▢ Cell Division: Binary fission; mitosis and meiosis absent

▢ Mesosome:

•
Traditional textbooks → respiration + DNA distribution during division
•
Modern interpretation → membrane infolding produced mainly as a fixation artifact

▢ Respiration: Respiratory electron-transport enzymes located in plasma membrane

▢ Reserve Materials:

•
Glycogen
•
PHB granules
•
Polyphosphate / volutin granules
•
Sulfur granules

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DISTRIBUTION

▢ Nature: Ubiquitous

▢ Habitats:

•
Soil
•
Freshwater + marine water
•
Air and dust
•
Plant + animal bodies
•
Hot springs
•
Salt lakes
•
Acidic + alkaline environments
•
Deep subsurface

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SIZE

Table 1: Bacterial Size

Category	Example / Point
Usual size	Approximately 0.5–5 µm
Traditional smallest-bacterium answer	Dialister pneumosintes
Smallest self-replicating cellular organisms	Mycoplasmas; e.g., Mycoplasma genitalium
Traditional largest-bacterium answer	Epulopiscium fishelsoni
Largest currently known bacterium	Thiomargarita magnifica

Exam Caution

Use the answer expected by the specific textbook or syllabus when an old entrance question asks 'smallest' or 'largest' bacterium.

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SHAPE AND ARRANGEMENT

Table 1: Bacterial Shapes

Shape / Arrangement	Meaning	Example
Coccus	Spherical / rounded	Micrococcus
Diplococcus	Pairs of cocci	Neisseria, Streptococcus pneumoniae
Streptococcus	Chain of cocci	Streptococcus pyogenes
Staphylococcus	Grape-like clusters	Staphylococcus aureus
Tetrad	Groups of 4 cocci	Micrococcus
Sarcina	Cubical packets of 8 or multiples	Sarcina
Bacillus	Rod-shaped	Bacillus, Escherichia coli
Diplobacillus	Pairs of rods	Some bacilli
Streptobacillus	Chains of rods	Streptobacillus
Coccobacillus	Short oval rod	Haemophilus
Vibrio	Comma-shaped curved rod	Vibrio cholerae
Spirillum	Rigid spiral	Spirillum
Spirochete	Thin flexible helical form	Treponema, Leptospira
Pleomorphic	Variable shape	Mycoplasma, Corynebacterium

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FLAGELLAR ARRANGEMENT

Table 1: Arrangement of Flagella

Type	Arrangement	Example
Atrichous	Flagella absent	Klebsiella, Shigella
Monotrichous	Single flagellum at one pole	Vibrio cholerae
Amphitrichous	One flagellum at each pole	Alcaligenes
Cephalotrichous	Tuft at one pole	Some spirilla
Lophotrichous	Tuft at one or both poles	Helicobacter pylori / some Pseudomonas
Peritrichous	Flagella distributed over entire surface	Escherichia coli, Salmonella, Clostridium

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FUNCTIONAL GROUPS

Table 1: Bacteria Classified by Ecological Function

Group	Function	Examples
Nitrogen-fixing bacteria	Atmospheric N₂ → biologically usable nitrogen compounds	Free-living: Azotobacter, Clostridium; symbiotic: Rhizobium
Ammonifying bacteria	Organic nitrogen → ammonia / ammonium	Bacillus, Proteus
Nitrite bacteria	Ammonia → nitrite	Nitrosomonas, Nitrosococcus
Nitrate bacteria	Nitrite → nitrate	Nitrobacter, Nitrococcus
Denitrifying bacteria	Nitrate → N₂ / N₂O	Paracoccus denitrificans, some Pseudomonas
Decomposers	Organic matter breakdown + mineral cycling	Many saprophytic bacteria

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CELLULAR STRUCTURE

▢ Overview:

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Glycocalyx → capsule / slime layer
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Cell wall
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Plasma membrane
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Cytoplasm
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Nucleoid
•
Plasmids
•
70S ribosomes
•
Inclusion bodies
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Flagella
•
Fimbriae / pili
•
Endospore in selected bacteria

Table 1: Bacterial Cell Components

Component	Structure / Function
Capsule / slime layer	Protection, adhesion, biofilm, resistance to drying + phagocytosis
Cell wall	Shape + osmotic protection; peptidoglycan in true bacteria
Plasma membrane	Selective transport, respiration, synthesis, secretion
Cytoplasm	Enzymes, metabolites, ribosomes, inclusions
Nucleoid	Main bacterial chromosome
Plasmid	Autonomously replicating extra-chromosomal DNA
Ribosome	Protein synthesis
Flagellum	Motility + chemotaxis
Fimbriae	Attachment to surfaces / host cells
Sex pilus	DNA transfer during conjugation
Endospore	Dormant resistant survival structure

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CAPSULE AND SLIME LAYER

Table 1: Glycocalyx

Feature	Capsule	Slime Layer
Organization	Well-organized + firmly attached	Diffuse + loosely attached
Visibility	Distinct boundary	Poorly defined
Main composition	Usually polysaccharide	Usually polysaccharide
Functions	Antiphagocytic, adhesion, virulence, desiccation resistance	Biofilm formation, adhesion, protection

▢ Important Points:

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Capsulated bacteria often produce smooth colonies / S type
•
Non-capsulated variants may produce rough colonies / R type
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Capsule is usually genetically determined
•
Capsular antigen may be called K antigen
•
Capsule may inhibit phagocytosis
•
Capsule is not a reproductive structure

▢ Examples:

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Klebsiella pneumoniae
•
Streptococcus pneumoniae
•
Neisseria meningitidis
•
Bacillus anthracis
•
Clostridium species

Special Capsule

Bacillus anthracis capsule = poly-D-glutamic acid; most other bacterial capsules are polysaccharides.

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CELL WALL

▢ Composition:

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Peptidoglycan / murein / mucopeptide
•
Alternating NAG + NAM
•
Tetrapeptide side chains
•
Peptide cross-linking

▢ Functions:

•
Maintains shape
•
Prevents osmotic lysis
•
Anchors surface structures
•
Contributes to antigenicity + pathogenicity

▢ Special Types:

Table 1: Special Cell-Wall Conditions

Organism / Group	Special Point
Mycoplasma	Cell wall absent
Archaea	Peptidoglycan absent; S-layer or pseudopeptidoglycan in some
Mycobacteria	Waxy wall rich in mycolic acids → acid-fastness
Chlamydia	Atypical wall; lacks classical peptidoglycan layer
Gram-positive bacteria	Thick peptidoglycan + teichoic acids
Gram-negative bacteria	Thin peptidoglycan + outer membrane containing LPS

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PLASMA MEMBRANE

▢ Structure:

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Phospholipid bilayer + proteins
•
Selective / differentially permeable
•
Typical unit-membrane appearance

▢ Functions:

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Transport of substances
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Electron transport + oxidative phosphorylation
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Cell-wall synthesis
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Lipid synthesis
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Secretion
•
Signal reception

▢ Sterols: Usually absent; Mycoplasma requires sterols in its membrane

▢ Mesosome:

❖ Traditional Textbook View:

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Respiration
•
DNA replication
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Equal distribution of genetic material
•
Cell division

❖ Modern View: Mesosomes are mainly artifacts produced during chemical fixation for electron microscopy.

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FLAGELLA

▢ Structure:

Table 1: Bacterial Flagellum

Part	Detail
Filament	Long external helical part made of flagellin
Hook	Connects filament with basal body
Basal body	Motor embedded in envelope
Energy	Usually proton motive force; sometimes sodium gradient

▢ Functions:

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Motility
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Chemotaxis
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Movement toward nutrients
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Movement away from harmful substances

▢ Important Points:

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Bacterial flagella lack 9 + 2 microtubule arrangement
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Flagellin is antigenic → H antigen
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Gram-negative basal body usually has 4 rings
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Gram-positive basal body usually has 2 rings
•
Flagella rotate rather than beat like eukaryotic flagella

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FIMBRIAE AND PILI

Table 1: Fimbriae vs Pili

Feature	Fimbriae	Pili
Length	Shorter	Usually longer
Number	Numerous	Few
Protein	Pilin or related proteins	Pilin
Main function	Attachment + biofilm formation	Conjugation, attachment or twitching motility
Example	Type 1 fimbriae	F pilus / sex pilus

▢ Type IV Pili:

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Attachment
•
Twitching motility
•
DNA uptake in some bacteria

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PLASMIDS

▢ Definition: Small extra-chromosomal, usually circular double-stranded DNA capable of autonomous replication

▢ General Features:

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Not essential for basic survival under ordinary conditions
•
May provide selective advantage
•
May occur in one or many copies
•
Can be transferred between bacteria
•
Important vectors in genetic engineering

Table 1: Important Types of Plasmids

Type	Function
F plasmid / fertility plasmid	Conjugation + sex-pilus formation
R plasmid	Antimicrobial resistance
Col plasmid	Bacteriocin / colicin production
Virulence plasmid	Toxins, adhesins or invasion factors
Degradative plasmid	Breakdown of unusual organic compounds
Metabolic plasmid	Special metabolic pathways
Ti plasmid	Crown-gall formation in Agrobacterium tumefaciens

▢ Episome:

❖ Definition: Plasmid or genetic element capable of existing independently and integrating into the bacterial chromosome

❖ Examples:

•
F factor
•
Temperate bacteriophage genome

❖ Correct Relationship: All episomes can exist as extra-chromosomal elements, but not all plasmids are episomes.

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SEX PILI

▢ Structure: Long protein appendage encoded commonly by F plasmid

▢ Function: Brings donor and recipient cells together during conjugation

▢ Donor: F⁺ bacterium

▢ Recipient: F⁻ bacterium

▢ Key Point: Bacteria do not have true male and female sexes; F⁺ and F⁻ indicate donor and recipient states.

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NUCLEOID AND RIBOSOMES

▢ Nucleoid:

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No nuclear membrane
•
Usually single circular double-stranded chromosome
•
Highly folded + supercoiled
•
Associated with DNA-binding proteins
•
Controls inheritance + cellular functions

▢ Ribosome:

•
70S = 50S + 30S
•
Made of rRNA + protein
•
Site of protein synthesis
•
May form polyribosomes / polysomes
•
Target of several antibacterial drugs

▢ Inclusions:

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Glycogen
•
PHB
•
Volutin / metachromatic granules
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Sulfur granules
•
Gas vesicles in some aquatic bacteria
•
Magnetosomes in magnetotactic bacteria

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GRAM POSITIVE VS GRAM NEGATIVE BACTERIA

Table 1: Gram-Positive vs Gram-Negative Bacteria

Feature	Gram-Positive	Gram-Negative
Gram-stain colour	Purple / violet	Pink / red
Peptidoglycan	Thick, multilayered	Thin, few layers
Outer membrane	Absent	Present
Teichoic acids	Present	Absent
Lipopolysaccharide / LPS	Absent	Present
Lipid content	Low	High
Periplasmic space	Small / poorly defined	Prominent
Porins	Absent	Present in outer membrane
Endotoxin	Absent	Lipid A of LPS
Resistance to drying	Generally greater	Generally lower
Sensitivity to lysozyme	Generally higher	Generally lower due to outer membrane
Sensitivity to penicillin G	Often greater, but variable	Often lower due to outer membrane, but variable
Flagellar basal-body rings	Usually 2	Usually 4
Examples	Staphylococcus, Streptococcus, Bacillus, Clostridium	Escherichia, Salmonella, Pseudomonas, Neisseria

▢ Gram Staining Steps: Crystal violet → Iodine → Alcohol / acetone decolorization → Safranin

▢ Mechanism:

❖ Gram Positive: Thick dehydrated peptidoglycan retains crystal-violet–iodine complex

❖ Gram Negative: Alcohol disrupts lipid-rich outer membrane; thin peptidoglycan loses primary stain → counterstain retained

Avoid Overgeneralization

Virulence, capsule, shape, antibiotic response and pathogenicity cannot be predicted reliably from Gram reaction alone.

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OXYGEN REQUIREMENT

Table 1: Bacteria Based on Oxygen Requirement

Type	Requirement	Examples
Obligate aerobes	Require oxygen	Mycobacterium tuberculosis, Pseudomonas aeruginosa, Azotobacter
Obligate anaerobes	Oxygen is toxic	Clostridium botulinum, Clostridium tetani, methanogens
Facultative anaerobes	Grow with or without oxygen; grow better with oxygen	Escherichia coli, Staphylococcus aureus, Salmonella
Microaerophiles	Require low oxygen concentration	Campylobacter jejuni, Helicobacter pylori
Aerotolerant anaerobes	Do not use oxygen but tolerate it	Lactic-acid bacteria; some Streptococcus

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NUTRITION

▢ Autotrophic:

Table 1: Autotrophic Nutrition

Type	Energy Source	Carbon Source	Examples
Photoautotrophic	Light	CO₂	Cyanobacteria, purple sulfur bacteria, green sulfur bacteria
Chemoautotrophic / chemolithotrophic	Oxidation of inorganic compounds	CO₂	Nitrifying, sulfur, iron and hydrogen bacteria

❖ Photoautotrophs:

•
Photosynthetic pigments present
•
Purple + green bacteria usually perform anoxygenic photosynthesis
•
H₂S or other reduced compounds may donate electrons
•
No O₂ evolved in anoxygenic photosynthesis
•
Cyanobacteria perform oxygenic photosynthesis using H₂O
•
Bacteriochlorophyll occurs in photosynthetic bacteria
•
Chlorophyll a occurs in cyanobacteria

❖ Chemoautotrophs:

Table 1: Chemoautotrophic Bacteria

Group	Reaction / Function	Examples
Nitrite bacteria	NH₃ / NH₄⁺ → NO₂⁻	Nitrosomonas, Nitrosococcus
Nitrate bacteria	NO₂⁻ → NO₃⁻	Nitrobacter
Sulfur bacteria	H₂S / sulfur compounds oxidized	Thiobacillus, Beggiatoa
Iron bacteria	Fe²⁺ → Fe³⁺	Leptothrix, Gallionella
Hydrogen bacteria	H₂ oxidized	Hydrogenomonas / hydrogen-oxidizing bacteria

▢ Heterotrophic:

Table 1: Heterotrophic Nutrition

Type	Source	Example
Parasitic	Living host	Pathogenic bacteria
Saprophytic	Dead organic matter	Decomposer bacteria
Symbiotic	Mutual association	Rhizobium in legume roots
Commensal	One benefits; other largely unaffected	Many intestinal bacteria

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REPRODUCTION AND SURVIVAL

▢ Vegetative Multiplication:

Table 1: Vegetative Multiplication

Method	Key Point
Binary fission	Most common; chromosome replicates → septum → two daughter cells
Budding	Unequal division in selected bacteria
Fragmentation	Occurs in some filamentous bacteria

▢ Endospore Formation:

❖ Definition: Dormant, highly resistant survival structure formed inside certain bacterial cells

❖ Common Genera:

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Bacillus
•
Clostridium

❖ Important Points:

•
Produced during unfavorable conditions
•
Sporulation / sporogenesis = endospore formation
•
Germination = return to vegetative cell
•
One vegetative cell usually forms one endospore
•
Endospore formation is not true reproduction
•
Resistant to heat, drying, radiation and chemicals
•
Contains calcium dipicolinate + small acid-soluble proteins
•
Layers → exosporium, spore coat, cortex, core wall, core

▢ Conidia: External spores formed by some actinomycetes such as Streptomyces

Critical Distinction

Binary fission increases cell number. Endospore formation preserves one cell lineage and does not increase the number of organisms.

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GENETIC RECOMBINATION

▢ Key Point: True sexual reproduction and meiosis are absent; genetic variation occurs by horizontal gene transfer.

Table 1: Genetic Recombination in Bacteria

Method	Mechanism	Classic Scientist / Organism
Transformation	Uptake of naked extracellular DNA by a competent cell	Griffith → Streptococcus pneumoniae
Transduction	Bacteriophage-mediated DNA transfer	Zinder + Lederberg → Salmonella
Conjugation	Direct cell-to-cell DNA transfer through conjugative apparatus	Lederberg + Tatum → Escherichia coli

▢ Transformation:

•
Donor DNA released into environment
•
Competent recipient binds + takes up DNA
•
DNA may recombine with recipient chromosome
•
Griffith demonstrated transformation in pneumococci
•
Avery, MacLeod and McCarty identified DNA as transforming principle

▢ Transduction:

Table 1: Types of Transduction

Type	Transferred DNA
Generalized transduction	Any bacterial gene may be transferred
Specialized transduction	Specific genes adjacent to prophage integration site

▢ Conjugation:

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Requires direct contact
•
Usually mediated by conjugative plasmid
•
F⁺ donor transfers F plasmid to F⁻ recipient
•
Hfr strain → F factor integrated into chromosome
•
Hfr conjugation may transfer chromosomal genes
•
F′ plasmid carries bacterial chromosomal genes

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ECONOMIC IMPORTANCE

▢ Beneficial Roles:

Table 1: Useful Activities of Bacteria

Use	Bacteria / Product
Curd / yogurt formation	Lactobacillus, Streptococcus thermophilus
Vinegar production	Acetobacter aceti
Nitrogen fixation	Rhizobium, Azotobacter, Clostridium
Decomposition + composting	Bacillus, Clostridium and many saprophytes
Vitamin production in intestine	Gut bacteria synthesize vitamin K and some B vitamins
Biogas / methane	Methanogenic archaea
Sewage treatment	Mixed bacterial communities
Bioremediation	Hydrocarbon- and pollutant-degrading bacteria
Genetic engineering	Plasmids + Escherichia coli
Single-cell protein	Methylophilus methylotrophus and other microbes

▢ Antibiotics:

Table 1: Antibiotics from Actinomycetes

Antibiotic	Source
Streptomycin	Streptomyces griseus
Neomycin	Streptomyces fradiae
Chloramphenicol	Streptomyces venezuelae
Chlortetracycline / Aureomycin	Streptomyces aureofaciens
Oxytetracycline	Streptomyces rimosus
Erythromycin	Saccharopolyspora erythraea

▢ Harmful Roles:

•
Human, animal and plant diseases
•
Food spoilage
•
Food poisoning
•
Dental caries
•
Material deterioration
•
Water contamination

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IMPORTANT HUMAN DISEASES

Table 1: Human Bacterial Diseases

Disease	Causative Bacterium
Tuberculosis	Mycobacterium tuberculosis
Typhoid fever	Salmonella enterica serovar Typhi
Cholera	Vibrio cholerae
Diphtheria	Corynebacterium diphtheriae
Tetanus	Clostridium tetani
Botulism	Clostridium botulinum
Plague	Yersinia pestis
Syphilis	Treponema pallidum
Gonorrhea	Neisseria gonorrhoeae
Meningococcal meningitis	Neisseria meningitidis
Pneumococcal pneumonia	Streptococcus pneumoniae
Whooping cough	Bordetella pertussis
Leprosy	Mycobacterium leprae
Anthrax	Bacillus anthracis

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PLANT DISEASES CAUSED BY BACTERIA

Table 1: Bacterial Diseases in Plants

Disease	Causative Bacterium
Potato wilt / brown rot	Ralstonia solanacearum (formerly Pseudomonas solanacearum)
Soft rot / blackleg of potato	Pectobacterium carotovorum (formerly Erwinia carotovora)
Citrus canker	Xanthomonas citri
Bacterial leaf blight of rice	Xanthomonas oryzae pv. oryzae
Black rot of cabbage	Xanthomonas campestris pv. campestris
Angular leaf spot of cotton	Xanthomonas citri pv. malvacearum
Leaf spot of cucumber	Xanthomonas cucurbitae
Crown gall	Agrobacterium tumefaciens
Fire blight of apple and pear	Erwinia amylovora
Tundu / yellow ear rot of wheat	Rathayibacter tritici (older name: Corynebacterium tritici)
Red stripe of sugarcane	Acidovorax avenae subsp. avenae

Common Exam Correction

Soft rot of potato is not caused by Pseudomonas solanacearum; that organism, now called Ralstonia solanacearum, causes bacterial wilt / brown rot.

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ARCHAEA

▢ Definition: Prokaryotic organisms forming a domain distinct from Bacteria

▢ Key Features:

•
No peptidoglycan
•
Cell wall may contain S-layer or pseudopeptidoglycan
•
Membrane lipids have ether-linked branched isoprenoids
•
Transcription and translation machinery partly resembles eukaryotes
•
Many tolerate extreme environments, but many also live in ordinary habitats

Table 1: Major Archaea Groups

Group	Habitat / Feature	Example
Methanogens	Strict anaerobes producing methane	Methanobacterium, Methanobrevibacter
Extreme halophiles	High-salt habitats	Halobacterium
Thermoacidophiles	Hot acidic habitats	Sulfolobus

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RICKETTSIAE

▢ Definition: Very small Gram-negative-like obligate intracellular bacteria

▢ Features:

•
Contain DNA + RNA
•
Have bacterial ribosomes
•
Replicate by binary fission inside host cells
•
Often transmitted by arthropod vectors
•
Reduced genomes + strong dependence on host metabolism
•
Not an intermediate form between bacteria and viruses

Table 1: Important Rickettsial Diseases

Disease	Agent / Group
Epidemic typhus	Rickettsia prowazekii
Murine typhus	Rickettsia typhi
Rocky Mountain spotted fever	Rickettsia rickettsii
Scrub typhus	Orientia tsutsugamushi
Q fever	Coxiella burnetii

▢ Weil-Felix Test: Historical, low-sensitivity agglutination test useful only for selected rickettsioses; not reliable for Q fever.

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MYCOPLASMA

▢ Other Name: PPLO / pleuropneumonia-like organisms

▢ Key Features:

•
Among smallest self-replicating cells
•
Cell wall absent
•
Highly pleomorphic
•
Plasma membrane contains sterols
•
Not affected by β-lactam antibiotics such as penicillin
•
Sensitive to drugs acting on ribosomes or DNA, depending on species
•
Multiply mainly by binary fission
•
Typical fried-egg colony appearance on special media
•
Genome usually small

Table 1: Important Mycoplasma Examples

Organism	Disease
Mycoplasma pneumoniae	Atypical pneumonia
Mycoplasma genitalium	Urogenital infection
Ureaplasma urealyticum	Urogenital infection

Plant Disease Terminology

Little leaf, grassy shoot, bunchy top-like syndromes attributed in older books to 'mycoplasma' are usually caused by phytoplasmas.

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ACTINOMYCETES

▢ Definition: Filamentous or branching Gram-positive bacteria

▢ Features:

•
May resemble fungi morphologically
•
Prokaryotic cell organization
•
Rich source of antibiotics
•
Important decomposers in soil
•
Some form conidia / arthrospores
•
Some cause human disease

Table 1: Important Actinomycetes

Genus	Importance
Streptomyces	Antibiotic production + soil decomposition
Actinomyces	Actinomycosis; anaerobic / microaerophilic
Nocardia	Nocardiosis; aerobic + weakly acid-fast
Frankia	Nitrogen-fixing root nodules in non-leguminous plants

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HIGH-YIELD ONE-LINERS

Table 1: CEE Rapid Revision

Question Point	Answer
Study of bacteria	Bacteriology
First observer of bacteria	Antonie van Leeuwenhoek
Term 'Bacterium'	Ehrenberg
Father of bacteriology	Robert Koch
Main bacterial cell-wall polymer	Peptidoglycan / murein
Peptidoglycan sugars	NAG + NAM
Bacterial ribosome	70S = 50S + 30S
Main multiplication method	Binary fission
Cell-wall-less bacterium	Mycoplasma
Dormant resistant bacterial structure	Endospore
Endospore-forming genera	Bacillus + Clostridium
Flagellar protein	Flagellin
Pilus protein	Pilin
Flagellar antigen	H antigen
Capsular antigen	K antigen
Extra-chromosomal replicating DNA	Plasmid
Integrated or autonomous plasmid-like element	Episome
F plasmid function	Conjugation + sex-pilus formation
R plasmid function	Drug resistance
DNA uptake from environment	Transformation
Phage-mediated DNA transfer	Transduction
Direct cell-to-cell DNA transfer	Conjugation
Gram-positive special polymer	Teichoic acid
Gram-negative endotoxin	Lipid A of LPS
Nitrite producer	Nitrosomonas
Nitrate producer	Nitrobacter
Symbiotic nitrogen fixer	Rhizobium
Free-living nitrogen fixer	Azotobacter
Methane-producing prokaryotes	Methanogenic archaea
Mycoplasma colony	Fried-egg appearance
Richest microbial source of antibiotics	Streptomyces
Bacterial wilt / brown rot of potato	Ralstonia solanacearum
Citrus canker	Xanthomonas citri
Crown gall	Agrobacterium tumefaciens

Q1.

Compared with mammalian nuclear DNA, typical bacterial chromosomal DNA:

📅CEE BDS 2024

Q2.

Which is correct about archaea (historically called archaebacteria)?

📅CEE MBBS 2023

Q3.

Nitrosomonas is: [IOM - 1997]

📅IOM - 1997

Q4.

The bacteria found in the root nodules of Leguminaceae is: [IOM -1999]

📅IOM -1999

Q5.

Denitrifying bacteria convert: [IOM - 1999]

📅IOM - 1999

Q6.

Which of the following is rod shaped bacteria? [MOE - 2064]

📅MOE - 2064

Q7.

Bacteria in an ecosystem act as: [MOE-2060]

📅MOE-2060

Q8.

Circular DNA is found in: [MOE - 2063]

📅MOE - 2063

Q9.

On unusual condition one of the following bacteria produces spore [IE - 2002]

📅IE - 2002

Q10.

In plants, fungi and bacteria, the proton pump in cells creates a negative membrane potential transporting which ion from the cytoplasm to the extracellular fluid? [IE - 2002]

📅IE - 2002

Q11.

Most primitive organisms are [IE -2003]

📅IE -2003

Q12.

In general bacteria, genes are regulated at: [IE - 2006]

📅IE - 2006

Q13.

Nitrogen fixation by organism requires conditions that are: [IE - 2007]

📅IE - 2007

Q14.

Cyanobacteria are [IE - 2008]

📅IE - 2008

Q15.

Which of the following kingdoms consist organism that can fix nitrogen? [IE - 2009]

📅IE - 2009

Q16.

Archaebacteria contains [IE - 2005]

📅IE - 2005

Q17.

What is wrong about fertility factor F+ present in bacteria? [BPKIHS 2002]

📅BPKIHS 2002

Q18.

Which is incorrect about bacteria? [BPKIHS 2002]

📅BPKIHS 2002

Q19.

"Little leaf of brinjal" is caused by: [BPKIHS 2004]

📅BPKIHS 2004

Q20.

Which of the following bacteria reduces the nitrates into gaseous form of Nitrogen? [BPKIHS 2006]

📅BPKIHS 2006

Q21.

E. coli in human intestine is present as [BPKIHS 2004]

📅BPKIHS 2004

Q22.

Bacterial DNA is identified as: [BPKIHS 2006]

📅BPKIHS 2006

Q23.

Which of the following is nitrifying bacteria [BPKIHS 2006]

📅BPKIHS 2006

Q24.

A bacterial cell divides every 20 minutes. After time period of 3 hrs, how many bacterial cell will be there? [BPKINS - 2016]

📅BPKINS - 2016

Q25.

Plasmids are [BPKIHS - 2014]

📅BPKIHS - 2014

Q26.

Bacteria without flagella is [BPKIHS - 2013]

📅BPKIHS - 2013

Q27.

Bacteria are [BPKIHS - 2011]

📅BPKIHS - 2011

Q28.

Bacterial DNA is [BPKIHS - 2012]

📅BPKIHS - 2012

Q29.

Bacteria without flagella is [IOM-2016]

📅IOM-2016

Q30.

Atmospheric nitrogen is converted to nitrogenous compound is [IOM-2016]

📅IOM-2016

Q31.

Which of the following bacteria shows darting type mortality? [IOM-2014]

📅IOM-2014

Q32.

Nitrosomonas is [IOM-209]

📅IOM-209

Q33.

Which one of the following is a free living aerobic nitrogen fixing bacteria? [IOM-2013]

📅IOM-2013

Q34.

The viral infection cycle that will cause the viral DNA to become integrated into the bacterial DNA is called [IOM-2015)

📅IOM-2015)

Q35.

Spherical bacterium is referred as [MOE 2014

📅MOE 2014

Q36.

Which one of the following is absent in bacteria? [MOE 2012)

📅MOE 2012)

Q37.

Rod shaped bacteria are called [MOE 2068)

📅MOE 2068)

Q38.

Akinetes occur in [MOE 2010)

📅MOE 2010)

21Bacteria

Table 1: Bacteria: Historical Points

Table 1: Bacterial Size

Table 1: Bacterial Shapes

Table 1: Arrangement of Flagella

Table 1: Bacteria Classified by Ecological Function

Table 1: Bacterial Cell Components

Table 1: Glycocalyx

Table 1: Special Cell-Wall Conditions

Table 1: Bacterial Flagellum

Table 1: Fimbriae vs Pili

Table 1: Important Types of Plasmids

Table 1: Gram-Positive vs Gram-Negative Bacteria

Table 1: Bacteria Based on Oxygen Requirement

Table 1: Autotrophic Nutrition

Table 1: Chemoautotrophic Bacteria

Table 1: Heterotrophic Nutrition

Table 1: Vegetative Multiplication

Table 1: Genetic Recombination in Bacteria

Table 1: Types of Transduction

Table 1: Useful Activities of Bacteria

Table 1: Antibiotics from Actinomycetes

Table 1: Human Bacterial Diseases

Table 1: Bacterial Diseases in Plants

Table 1: Major Archaea Groups

Table 1: Important Rickettsial Diseases

Table 1: Important Mycoplasma Examples

Table 1: Important Actinomycetes

Table 1: CEE Rapid Revision

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