Biological treatment of leather tanning industrial wastewater using free living bacteria (2)
Bacterial Ecology. Definition - Relation between bacteria and non-living environment - Relation...
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Transcript of Bacterial Ecology. Definition - Relation between bacteria and non-living environment - Relation...
Bacterial EcologyBacterial Ecology
Bacterial EcologyBacterial Ecology
DefinitionDefinition
- Relation between bacteria and non-living environment
- Relation between bacteria and other living organisms
- Relation between bacteria with each other
Relation with non-living environmentRelation with non-living environment
Bacteria plays roles as:Bacteria plays roles as:
ProductionProductionProducers
DegradationDegradationDegeneratersConsumers
Relation with other living organisms Relation with other living organisms (Symbiosis)(Symbiosis)
Mutualism
(Transient and resident microflora)
Commensalism
Parasitism
Relation with each other Relation with each other (Symbiosis)(Symbiosis)
Indifference
Competition
Antagonism
Synergism
Bacterial traits changes are due to:
1. Changes in environmental conditions
2. Changes in the genetic codes
Bacterial GeneticsBacterial Genetics(Studying heritage variations in bacterial traits)(Studying heritage variations in bacterial traits)
Changes in environmental conditions Changes in environmental conditions
Brucella species are bacillus in 21 ○C and coccobacillus in 37 ○C
Mycobacterium tuberculosis shows filamentous in 24 ○C when exposing glycerin.
pneumococcus loses its capsule after some invitro culture.
Staphylococcus aureus is not able to produce golden pigment in absence of oxygen.
Salmonella species loses flagella when exposing phenol on culture.
Adding calcium to Bacillus anthracis culture stops converting bacteria to spore form.
Changes in bacterial traitsChanges in bacterial traits
Changes in the genetic codes
1- Intermicrobial exchange
2- Mutations
(point mutations, insertions, deletions)
Intermicrobial exchangeIntermicrobial exchange
Transformation
(Capturing DNA from solution)
Transduction
(Phage-mediated)
Conjugation
(Bacterial Sex)
Explored by F. Griffith (1928) using pneumococci
The DNA released from a degenerated bacterium enters into another bacterium.
There is no vector or mediation in this type of gene exchange.
Transformation Transformation
DN
A-M
edia
ted
Tra
nsf
orm
atio
nD
NA
-Med
iate
d T
ran
sfor
mat
ion
DN
A-M
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ted
Tra
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orm
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nD
NA
-Med
iate
d T
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Intermicrobial exchanges by vectorsIntermicrobial exchanges by vectors
15
Characteristics of genetic vectorsCharacteristics of genetic vectors
must be capable of carrying a significant piece of donor DNAmust be readily accepted by the host
Plasmids – small, well characterized, easy to manipulate & can be transferred into appropriate host cells through transformation Bacteriophages – have the natural ability to inject their DNA into bacterial hosts through transduction
TransductionTransduction(madiated by phage)(madiated by phage)
Microbe Library, American Society for Microbiology
www.microbelibrary.org
Lytic versus LysogenicLytic versus Lysogenic
Gen
eral
ized
Tra
nsd
uct
ion
Gen
eral
ized
Tra
nsd
uct
ion
Gen
eral
ized
Tra
nsd
uct
ion
Gen
eral
ized
Tra
nsd
uct
ion
TransductionTransduction
Specialized (Restricted):
Transduction in which only certain donor genes can be transferred.
TransductionTransduction(Restricted)(Restricted)
Restricted TransductionRestricted Transduction(Lysogenic Phage)(Lysogenic Phage)
gal
bio
gal bio
gal bio
gal
bio
bio
gal
TransductionTransduction
Significance
– Common in Gram+ bacteria
– Lysogenic (phage) conversion
• e.g. Corynebacterium diptheriae toxin
–Toxin derived from lysogenic phage
ConjugationConjugation
Definition: Gene transfer from a donor to a recipient by direct physical contact between cells
Mating types in bacteriaDonor
F factor (Fertility factor)
F (sex) pilusRecipient
Lacks an F factor
ConjugationConjugation
Significance Gram - bacteria
Antibiotic resistance Gram + bacteria
Production of adhesive material by donor cells
ConjugationConjugation
Con
juga
tion
: S
ex o
r F
Pil
us
Con
juga
tion
: S
ex o
r F
Pil
us
Pla
smid
sP
lasm
ids
PlasmidsPlasmids
Definition:
Extrachromosomal genetic elements that are capable of autonomous replication (replicon)
Plasmid Types:
Congugative & Non-congugativeCongugative & Non-congugativeEpisome - a plasmid that can integrate into the
chromosomeCasmid – An integration of a plasmid and a
bacteriophage
Phenotypic effectsPhenotypic effects
Fertility (F factor)
Bacteriocinogenic (or encoding some other toxins)
Resistance (R factors)
Structure of R FactorsStructure of R Factors
RTFConjugative
plasmidTransfer genes
Tn 9
Tn 2
1
Tn 10Tn 8
RTF
R determinant
R determinantResistance genes
Sel
f-T
ran
smis
sib
le R
Pla
smid
Sel
f-T
ran
smis
sib
le R
Pla
smid
Con
juga
tion
: F
Pla
smid
C
onju
gati
on:
F P
lasm
id
Tra
nsf
erT
ran
sfer
ConjugationConjugation
FF+ + andand HFr cellsHFr cells
Integrated (Hfr)(High Frequency of Recombination)
F+ Hfr
Hfr and F’ cellsHfr and F’ cells
Hfr F’
Mechanism of Hfr x FMechanism of Hfr x F-- Crosses Crosses
Hfr F- Hfr F-
Hfr F-Hfr F-
Mechanism of F’ x FMechanism of F’ x F-- Crosses Crosses
F’ F’F’ F’
F’ F- F’ F-
Transposable Genetic ElementsTransposable Genetic Elements
Definition: Segments of DNA that are able to move from one location to another (across the genome or from one genome to another)
Properties
– “Random” movement
• Transposase
– Transposition may be accompanied by duplication
Types of Transposable Genetic ElementsTypes of Transposable Genetic Elements
Transposons (Tn)/ Insertion elements (IS)Definition: Elements that carry other genes in
addition to those involved in transpositionNomenclature - Tn10, IS6110Structure
Composite Tns Importance
Antibiotic resistance
Epidemiology and evolutionary studies
IS ISResistance Gene(s)
IS ISResistance Gene(s)