Bacterial growth metabolism in power point .ppt

Bacterial growth metabolism

1. Dr. Jyotsna Agarwal
Professor, Dept. of Microbiology,
King George’s Medical University
Bacterial Taxonomy

2. •Classification: Orderly arrangement and
placement of bacteria based on certain characters
ie. Address
•Nomenclature: giving Names
What is taxonomy

3. •Families - related bacteria eg. Enterobacteriaceae
•Within a family - numerous genus eg. Escherichia,
Klebsiella, Salmonella
•A genus contains many species eg. E. coli, E. tarda

4. Species
•Taxonomical unit
•Based on morpholopgy, biochemical properties &
antigenic characters
•Nucleotide base ratio constant for a given species
(AT : GC)
•Genetic homology demonstrated by DNA
hybridization > 98%

5. Interspecies Classification
They are identical, may show some differences
due to mutation
•Biotype - based on biochemical reactions
•Serotype - based on antigens on bacteria
•Phage type - susceptibility to particular phage
•Colicin type - substance secreted by some bacteria
•Molecular typing: Plasmid profile, DNA sequence

6. •A bacterial population derived from a single
bacteria by binary fission is called CLONE
•A bacterial population obtained from a particular
source is called STRAIN

7. Nomenclature
•Casual name / Scientific name:
eg. Gonococcus / Neisseriae gonorrhoeae
Pneumococcus / Streptococcus pneumoniae
•Name could be a character: Staphylococcus aureus
•Place of discovery: Salmonella london
•Scientist: Clostridium welchii
•Disease: Clostridium tetani

8. Bacterial Growth
& Metabolism

9. Prokaryotes
•Asexual reproduction - binary fission
•Generation time or doubling time
•Clinical implication?

10. Bacterial Growth Curve
4 phases

11. What is a Bacterial colony?
•Colony - visible growth on a
culture plate.
•Colony Forming Unit- CFU ?

12. Bacterial Nutrition
•Autotrophs - photo /chemo
•Heterotrophs
–Need preformed organic compounds
–Includes most pathogenic bacteria
•Fastidious heterotrophs

13. Bacterial Metabolism
•Help us in identifying bacteria by their end
products
•Help us in knowing how to inhibit bacteria

14. Energy Generating Process
•Sugars formed or obtained - broken down to
release energy
–Aerobic respiration
–Anaerobic respiration
–Fermentation
•Microbes that use aerobic respiration, detoxify
generated waste:
Catalase: H
2O
2 ------- H
20 and 0
2
Superoxide dismutase : oxygen radical ----- H
20 and O
2

15. Energy Generating Process
•Aerobic respiration:
–COMPLETE breakdown of glucose to CO
2
& H
2
O
–Final electron receptor O2
–Yield = 38 ATP
•Fermentation:
– Yield = 2 ATP
– Endproducts: Lactic acid/Alcohol
– Final electron receptor is organic molecule
•Anaerobic respiration:
– Yield >2 <38 ATP
– Absence of oxygen

16. Factors affecting bacterial
growth
•Oxygen : Obligate /facultative; aerobes /
anaerobes; microaerophilics
•Temperature
•Ph
•Osmotic pressure
•CO
2

17. Summary
•Bacterial Taxonomy
•Bacterial growth curve
•Fastidious /non fastidious bacteria
•Obligate/facultative anaerobe
•Obligate aerobes