Morphology of bacteria revision notes microbiology

• BACTERIA
• BLUE GREEN ALGAE
• ARCHEA
• FUNGI
• ALGAE OTHER THAN BLUE
GREEN ALGAE
• PROTOZOA
TONY SCARIA 2010 KMC

TEICOIC ACID
THICK LAYER OF
PEPTIDOGLYCAN

PORIN
PERIPLASMIC
SPACE
OUTER MEMBRANE
PORIN IN
OTERMEMBRANE
HELP IN
MOVEMNET OF
SUBSTANCES IN &
OUT

THIN LAYER OF
PEPTIDOGLYCANTHICK LAYER OF
PEPTIDOGLYCAN

MESOSOME
• INVAGINATION OF PLASMA
MEMBRANE
• PRINCIPAL SITES OF
RESPIRATORY ENZYME

 CELL MEMBRANE OF MYCOPLASMA IS HAVING ERGOSTEROL IN CELL
MEMBRANE

 USUALLY MADE UP OF
POLYSACCHARIDE
 EXCEPT IN BACILLUS ANTHRACIS IN
WHICH IT IS MADE UPIOF POLYPEPTIDE

 Pneumococcus
 Meningococcus
 Klebsiella
 Cryptococcus
 Bacillus anthracis  polypeptide

 Negative staining
 Quellung reaction

 Babes ernest granules
 Polar bodies
 Volutin granules
 First described in spirillum volutans
 Reddish violet with methylene blue
 Polymetaphosphate
 Highly basophilic
 Utilised for nucleic acid synthesis

 Corynebacterium diphtheria
 Spirillum volutans
 Gardenella vaginalis

 Alberts staining
 Neissers stain
 Ponders stain
 Loefflers methylene blue

 Organs of locomotion
 Movement of all motile organism
except spirochetes

 FLAGELLAE
 Single polar (Monotrichous) - Vibrio, pseudomonas
 Polar tuft (Lophotrj. chous) –
 Spirilla,, Helicobacter,Campylobacter
 Peritrichous - Salmonella, proteus, E.coli, clostridium, Listeria
 Amphitrichous. - Campylobacter
 Endoflagellae / axial filaments - Spirochaetes

Monotrichous
Vibrio cholera
Pseudomonas
Peritrichous
Salmonella Typhi, E. coli
Amphitrichous flagella
Lophotrichous
helicobacter pylori

Direct motility
 Silver impregnation
Indirect motility
 (a) dark-ground microscopy,
 (b) hanging drop method, or
 (c) observing spreading type growth
on semisolid media, such as mannitol
motility medium

 Differential motility (Motility at different temperature) –
 Yersinia enterocolitica &
 Listeria monocytogenes

Darting motility vibrio cholera
Tumbling motility Listeria
Swarming Proteus
clostridium tetani
Bacillus cereus
Falling leaf like Giardia

 In gram negative bacteria
 Organs of adhesion
 Sex pili  a special type of fimbriae

Exotoxin Endotoxin
Produced extracellularly by both gram +ve &
gram –ve bacteria
Component of outermembrane of gram
negative bacteria (except for listeria
monocytogenes  only gram positive bacteria
which produces endotoxin )
Proteins with A & B components Lipopolysaccharide
Action enzymatic No enzymatic action
Highly antigenic Weakly antigenic
Can be toxoided Cant be toxoided

TRANSFERABLE DRUG
RESISTANCE
 D/T R DETERMINANT (PLASMID)
 MULTIPLE DRUG RESISTANCE
 HIGH DEGREE OF RESISTANCE
 HIGH DOSE OF DRUG INEFFECTIVE
 RESISTANCE SPREADS AMONG
BACTERIA
MUTATIONAL DRUG RESISTANC E
 D/T MUTATION (D/T BACTERIAL
DNA)
 SINGLE DRUG RESISTANCE
 LOW DEGREE OF RESISTANCE
 HIGH DOSE EFFECTIVE
 RESISTANCE DONOT SPREAD
AMONG BACTERIA

 One step mutation streptomyocin resistance
 Step wise mutation penicillin resistance
 DRUG RESISTANCE IN TB IS D/T MUTATION
 TO Px MDR MULTIDRUG TX

Gene transfer
in bacteria
Tranformation
Via
bacteriophages
Tranduction
Lysogenic
conversion
Via F plasmid/
sex plasmid
Conjugation
R plasmid & col
plasmid
HFR
Sexduction

Virulent phage Temperate phages
Replicate only via lytic cycle That can follow both lytic & lysogenic cycle
Eg  T1 & T2 phage of E coli Eg λ phage of E coli

UV rays & nitrogen mustard can cause induction of bacteria  can
convert lysogenic cycle in to lytic cycle (separation of phage
chromosome from bacteria)

 DNA is transferred from one bacterium to another by a defective / mispackaged
phage with bacterial genes
 Can transfer plasmid apart from chromosomal DNA

Generalised transduction Specialised / restricted transduction
Transfer of pure bacterial genome Transfer of bacterial genes which are close to
phage DNA d/t defective excision
Temperate / virulent phage Temperate phage only

 MOST WIDE SPREAD MECHANISM OF GENE TRANSFER
 PLASMID DETERMINING PENICILLIN RESISTANCE ARE TRANSFERRED FROM
CELL TO CELL BY TRANSDUCTION
 BACTERIOPHAGE  LYTIC CYCLE & LYSOGENIC CYCLE
 LYSOGENIC CYCLE
 PHAGE DNA INCORPORATED IN BACTERIAL DNA  NEW CHARCTERISTICS
 DIPHTHERIA TOXIN PRODUCTION
 PENCILLIN RESISTANCE IN STAPHYLOCOCCI

 Prophage itself supplies genetic information such as that the lysogenic bacteria
exhibit a new characteristic not displayed by non lysogenic bacteria
 Toxin production
 Diphtheria toxin
 Cholera toxin

 Uptake of soluble DNA fragments in the environment directly through cell wall

 IN STREPTOCOCCUS PNEUMONIAE

 The ability of bacteria to take up DNA fragments through cell wall  competence
 Depends on enzymes

 LEDERBERG & TATUM IN ECOLI K12
 Transfer of genetic material b/w bacteria through abridge like connection
 Genes encoding the sex pilusa are located on fertility /sex/F plasmid or transfer
factor
 F+  with F plasmid
 F- without F palasmid
 IF PLASMID CODES FOR ANTIBIOTIC RESIATENCE  R FACTOR

DONOR STATUS IS
DETERMINED BY
PRESENCE OF
PLASMID

Conjugation tube breaks
before full transfer of DNA
so the recipient bacterial
cell will remain F-(it
receives only part of
bacteria DNA)

 HFR is reversible
 May sometimes carry part of bacterial chromosome to form F’
 Tranfer of F’ plasmid to F- is called transduction

 R factor = F factor + antibiotic resistance genes (r determinants)
 Transfer of R plasmid via conjugation is the commonest mode of spread of Abx
resistance

 F plasmid + bacteriocin gene (producing bacteriocin that kill other bacteria)

Morphology of bacteria revision notes microbiology

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