Question

Describe the microbial growth curve in a closed system.

Answer 1

A closed system is considered to be occur in batch culture. A batch culture is a culture in which no new nutrient is added to the bacterial culture or removed from the culture. SO after sometime bacterial population enters into stationary phase. because of exhaustion of the nutrients in the media. Eventually the population enters death phase. Growth in batch culture is divided into 4 distinct phase- Lag phase, Log phase, Stationary phase and Death phase.

Lag phase- It is the first most phase of the growth curve. In this phase there is no change in the number of bacterial cells, but only increase in the mass. It is also called the adaptation period of the cell in which they adapt into new environment.

Log phase- It is the period of increasing growth, in this phase cells grow by dividing by binary fission. The cells divide at a constant rate depending on the nutrients of culture media. The rate of growth is called generation time or the doubling time.

Stationary phase- In this phase cells stop dividing because of lack of nutrients in the culture media. It happens because no nutrients are being added or waste (might be inhibitory products) is being removed from the media, so eventually the nutrients from culture exhausts and cells have no energy to divide further, also there is no enough space for new cells.

Death phase- After reaching to stationary phase, death phase follows. In the death phase the number of bacterial viable cells decreases and the growth curve reverse.

Bacterial growth curve in Closed system

GROWTH PHASE 1 LAG LOG STATIONARY DENTH Number of living cells Scanned with CamScanner 1. Time