Question

dow Help rition and Growth 2 ") Untitled-Edited Insert Table Chart Text Shape Media Comment Share Understand the different factors that affect bacterial growth and how they influence the speed of population growth. Know any terminology associated with these factors

Answer 1

Bacterial growth in a batch culture could be divided into 4 phases as follows:

1. Lag phase- This is the acclimitization phase for bacteria. During this period, culture growth rate is generally low as the cell adapts to the culture conditions.
2. Log phase- This is the exponential phase of the batch culture, where the culture growth rate is significantly higher than that death rate.
3. Stationary phase- This is the phase in which the culture has attained stability, the culture growth rate is equal to the death rate. As such there is no increase or decrease in the population.
4. Death phase- This is the decline phase, characterised by the decreasing culture pupulation due to nutrient scarcity and debris collection in the culture.

Environmental factors are responsible for controlling the rate of growth in bacterial culture. Some of these factors are described as below:

• pH- Bacterial populations require an optimum pH to survive and grow, any change in pH will lead to a decline in bacterial growth and even cell death,.
• Temperature- Low temperatures generally tend to reduce growth rates of bacteria in culture.
• Oxygen- Depending on the aerobic or anaerobic nature of bacterial culture, oxygen concentration can either decrease or increase the bacterial growth.
• Nutrient requirement- decreasing nutrient concentration will lead to decline in bacterial growth rate.

Other factors that can affect bacterial growth rate are sparging and aeration rates as well as water activity.