To construct a growth curve using aspergillus niger.

Aim: To construct a growth curve using aspergillus niger.

Requirements: Master culture of Aspergillus niger
Prepared Potato dextrose agar(PDA) slants
Flasks
Sterile water

Medium composition:
Sucrose 3gm
Sodium nitrate 0.2gm
Potassium dihydrogen phosphate 0.1gm
Magnesium sulphate 0.05gm
Potassium chloride 0.05gm
Ferrous sulphate 0.0001gm
Distilled water 1000ml
pH 5.6


Procedure:
Form master culture of Aspergillus niger, potato dextrose agar slants were incubated at room temp. for 4 days. The medium containing. Above composition was prepared and sterilized. The spores were suspended in sterile water and inoculated in to above medium.this kept on rotary shaker. After two days 10 ml of this broth was used as inoculum for another flask containing 100ml of medium and placed on rotary shaker.
Samples of 10ml were withdrawn using sterile pipette at 24hr interval and transplanted in to clean test-tubes. Samples were collected at 24,48,72,96hr. cell mass of each sample was determined by weighing the cell sediment. After centrifugation and decanting the supernant and weighing the empty tubes later. The differences in the two weight give the cell mass.
Prior to weighing the cell sediment, cells were dried by vacuum drier at 550c overnight. Dry weight of mycelium was found per each sample and noted against sampling hour. A graph plotted taking time on X-axis and weight of dried mycilium on Y-axis. A culture was drawn smoothly through the points, which is the fungal curve.

Observation:

Fungal growth curve:

Result:

As shown in curve we get the growth in the fungus till 72 hrs. Then after there was a decline in the growth of fungus.

Conclusion:

As shown in the graph we can see the four phases in the growth of the fungus.
Lag phase: Here the lag phase is for 24 hrs, which can be observed from the graph. There is a lag in the growth during these hours in fungus.

Log phase: Here the log phase is for 48 hrs in which the growth of fungus slowly increases by utilizing the nutrient from the media.

Stationary phase: After this there was a segment growth of fungus. This is due to lack of sufficient nutrient. Here the stationary phase last for small period of time.
Decline phase: After the stationary phase there is a decline in fungus growth due to total lack of nutrient or formation of some toxic material.