Bacterial physiology, factors influencing growth, general characteristics of the bacterial growth curve

Binary Fission

1. Chromosome replication and separation
2. Cell elongation and septum formation
3. Growth of the cell wall
4. Bacterial cell division (asymmetric division: minicell)

Factors influencing growth

• Temperature

• Moisture

• pH

• Osmotic pressure

• Nutrients

• Mechanical forces

• radiation

Stenothermic

Organisms with a narrow temperature tolerance range

Euthermic

Organisms with a broad temperature tolerance range

Psychrophilic

Thrive in cold temperatures

Mesophilic

Prefer moderate temperatures

Thermophilic

Grow at high temperatures

Extreme thermophilic

Live in very high-temperature environments

Water Content

Increased water requirement, they tolerate dehydration less easily

Osmotic Pressure

They are more resistant to changes in osmotic pressure than plant and animal cells—two types of osmophiles (organisms that prefer high osmotic pressure) are halophiles and saccharophiles

pH

Effect on nutrient transport and enzyme activity

Lag phase

No increase in bacterial cells

Log phase

Exponential increase in bacterial cells

Stationary phase

Stagnant number

Death phase

Exponential decrease of bacterial cells