Bacterial Physiology Flashcards
(46 cards)
Bacterial Physiology Def
Study of bacterial survival, reproduction and growth processes. Used to understand colonisation and infection for diagnostic, prevention and treatment
Liquid medium Conditions
Sterile contents before inoculation, agitation (allows air flow and gas exhange, good oxygen and CO2 levels) and temp can be adjusted for bacteria
Liquid medium growth estimate
10^9 cfu/ml. (CFU = colony forming unit. No. of cells multiplying to form colonies)
Solid Media Outline
Liquid media with the addition of agar. Melts at 100 degree C and solidifies at 40 degrees C. Sterilised before innoculation by aitoclaving. Used for single colony purification
Examples of aseptic techniques
Work in a laminar air flow cabinet or beside Bunsen burner (continuous sterile airflow) and use (UV) sterilised equipment
How media can be sterilised
Boiling, autoclaving, dry heat and sterile filtration
Simple Media Def
Solid medium with the most general nutrients necessary for bacterial survival
Complex media def
Solid medium with most general nutrients and specific nutrients for particular bacteria
Selective Media Def
Medium that contains antimicrobial to kill all but relevant microorganisms
Differential Media Def
Medium that contains dye that changes colour due to substances produced by specific bacteria for identification
Methods of Bacterial Enumeration
Spectrophotometry measures alive/dead cells by seeing scattering of light (indirect, optical density) and dilution of bacteria on cell plate (viable cell count)(x dil factor = x cfu/ml)
Binary Fission steps
DNA duplication, second DNA migrates to other side of cell. Splitting of cell down the middle due to cell wall growth in middle of cell. Produces 2 identical daughter cells
How Chromosome Divides
X by 2
4 Phases of Bacterial Growth
Lag, log Stationary and Decline
Lag Phase Def
Period of little growth due to bacteria aclimatising to their enviorment
Log Phase Def
Period of exponential growth. As there isn’t a lot of waste produced and they are in a nutreint rich enviorment. Bacteria birth > death
Stationary Phase
Period of stagnancy. Cell birth = cell death
Decline phase
Period of less bacteria. Cell birth < cell death
When is best phase for antibiotic intervention
Log. As cells are rapidly growing
How do bacteria get energy without mitochondria
Heterotrophes intake nutrients (carbohydrates, proteins..). Glycolysis and TCA occur in cytoplasm. ETC happens across cell membrane. This means they are highly dependent on external enviorment
Aerobe Def
Require oxygen for survival and reproduction
Facultative Anaerobe Def
Do not require oxygen but can still function in it’s presence. Will shift to aerobic respiration in oxygens presence
Obligate Anaerobe Def
Die in the presence of oxygen. Bacteria don’t contain enzymes to neutralise oxidative agents causing cell death. Have to use other final electron receptors (eg NO2, organis acids) on a different cytochrome path or stop at lactic acid fermentation in glycolosis
Microaerophiles Def
Bacteria that can respire in the presence of oxygen but function optimally with a higher percentage of CO2 then oxygen
