bacte lec (factors affecting growth of bacteria)

aerobic

needs oxygen

Obligate aerobes

can grow only in the presence of oxygen (e.g., P. aeruginosa).

Facultative aerobes

are ordinary aerobes but can also grow without oxygen (e.g., E. coli)

Microaerophilic bacteria

those bacteria that can grow in the presence of low oxygen and in the presence of low (4%) concentration of carbon dioxide (e.g., Campylobacter jejuni).

anaerobic bacteria

can love without O2; lack superoxide dismutase and catalase hence oxygen is lethal to these organisms

obligate anaerobes

are the bacteria that can grow only in the absence of oxygen (e.g., Clostridium sp)

aerotolerant anaerobes

use fermentation as process for producing energy rather than utilizing oxygen (e.g., Cutibacterium, Lactocaillus)

capnophilic

• the organisms that require higher amounts of carbon dioxide (CO2) for their growth are called ——-

• example of bacteria: H. influenzae, Brucella abortus

37C

optimum temperature for most of the pathogenic bacteria is

Psychrophiles

these bacteria are cold loving microbes that grow within a temp range of 0-20. Most of soil and water saprophytes belong to this group. ex: Arthrobacter sp, Psychrobacter sp

Mesophiles

these are moderate temp loving microbes that grow between 25C and 40C. Most of pathogenic bacteria belong to this group

Thermophiles

These are het loving microbes. They can grow at a high temp range of 55-80C. ex; B. stearothermophilus

pH 7.2 and 7.6

most pathogenic bacteria grow between pH — and —

V. cholerae

bacteria that can grow at an alkaline (8.2-8.9) pH

Phototrops

bacteria deriving energy from sunlight

Chemoautotrophs

bacteria deriving energy from chemical sources

Osmophilic bacteria

organisms requiring high osmotic pressures are called

plasmolysis

sudden exposure of bacteria to hypertonic solution may cause osmotic withdrawal of water, leading to osmotic shrinkage of the protoplasm

plasmoptysis

sudden transfer of bacteria from concentrated solution to distilled water may cause excessive inhibition of water leading to swelling and bursting of cell