Question

1. How does bacteria reproduce? Know the phases of bacterial growth with what happens in each phase.

2. What is CFU?

3. Know in detail about the factors affecting bacterial growth including physical factors (pH, temperature, water, oxygen, osmotic pressure) and nutritional factors.

4. How does bacteria interact with each other?

5. What is sporulation and germination?

Answer 1

There is very common mode of reproduction in bacteria found as binary fission, in which a bacterial cell divide into two new cell. In bacteria, the mode of reproduction is also the bacterial growth, because they are unicellular. Generally, unicellular organisms multiply by fission. During bacterial growth, they show a different characteristics phases in which you will find a lag phase, log phase, stationary phase and death phase.

Lag phase is the phase in which bacteria adapt themselves to grow. This phase of maturation without bacteria cannot divide.

Log phase is also known as exponential phase, in which bacteria divide exponentially or rapidly increase their number. This phase depend upon various factors like nutrient. Nutrient availability is restricted so this phase also terminates after sometimes.

Stationary phase is represented by the completion of division and hance, almost the bacterial population remains same. The bacterial growth in this phase is restricted because of missing of factors like nutrient.

Death phase characterises by the death of bacteria either due nutritional lack or various cause. Remember, bacteria show division which remarks the formation of new progeny and elimination of parents.

CFU: CFU the term stands for colony forming unit, which refers to number of viable bacteria for multiplication.

Bacterial growth depend on various factors like pH, temperature, osmotic pressure, nutrition, etc. Most of the bacteria grow in slightly acidic ph range from 6 to 7. Bacteria show diverse temperature range in growth from 25 to 45 degree centigrade. Medium contains 80 to 90% water is preferred also for bacteria to grow. Bacteria show optimum growth in carbin rich nutrient medium.

Bacterial communication may be through secretion of chemicals or may also happen by the physical contact. Bacteria have thin outer layer. It is smooth and known as gkycocalx, help in bacterial cohesion/adhesion.

Sporulation is production of spore in unfavourable condition of growth when there is lack of nutrient, whether germination is the process of removal of dormancy or cells become metabolically active when favorable condition rises.