Question

41. The growth of microbes in an auenic culture on a solid medium may be limited by all of the following except Depletion of nutrients Accumulation of waste products. Lack of space or attachment sites Competition from other micrches. - -

Answer 1

Axenic culture is preparation in which only one species of organism is only present and it free of all the other contaminating organism. Culture/ Growth medium is a liquid or gel designed to support the growth of microbes.

There are 4 phases in the growth process of microbes. Those are:

• Lag Phase: Initial adapting stage
• Log Phase: Exponential(2n) increase stage or growth stage
• Stationary Phase: Plateau stage where dying cells equals to dividing cells
• Death Phase: Exponential decrease in the number of microbes

There are both Physical and Chemical factors that affect the growth of microbes.

Physical factors: pH, Temperature, Oxygen, Salinity, Pressure, Moisture

Chemical factors: Nutrients, Sulphur, minerals, Phosphorous, Nitrogen, Carbon

The growth of microbes are limited because of the below:

• depletion of nutrients

Nutrients are vital for the growth of microbes and the diminishing amount of nutrients can limit its growth.

• accumulation of waste products

Bacterias produce waste products by their metabolism but when it exceeds a limit, it becomes toxic and it inhibits its further growth.

• competition from other microbes

Competition between microbes for nutrient and survival can limit its growth.

So the answer is lack of space or attachment sites which is not a factor which limits the growth of microbes.