Microbial production of cellulase:

SOURCE:  Cellulases are produced by bacteria like Pseudomonas fluorescens, P. cellulosa as well as by fungi like Aspergillus niger, A.fumigatus, T.reesai.

Mode of action of enzyme:
Cellulase breaks down the cellulose molecules into monosaccharides or shorter polysaccharide and oligosaccharides by catalyzing the hydrolysis of the 1,4 beta- D glycosidic linkages of cellulose.

Type of fermentation: Cellulose is produced on a large scale by solid state fermentation.

Production parameters:
A. From bacterial source-
Composition of production medium in case of P. fluorescens:

Component.                        Amount (g/L)
Glucose.                               0.5
Peptone.                               0.75
FeSO4.                                 0.01
KH2PO4.                               0.5
MgSO4.                                 0.5

Temperature of fermentation is maintained in the range 30-40 C.
pH of production medium is maintained in the range of 9-11.
Production of enzyme begins when maximum cell growth is reached after 24 hours.
C source: glucose, lactose, fructose, glycerol
N source: peptone, ammonium sulphate, urea

After optimization, mass production is carried in 1 L of optimized media at 40 C for 40 hours at pH of 10 in a rotary shaker at 110 rpm.

Downstream processing:
⦁ Culture medium is centrifuged at 5000 rpm for 15 minutes to obtain enzyme extract.
⦁ Cellulase product is then concentrated by ammonium sulphate precipitation or acetone precipitation.
⦁ Finally, purification is carried out by column chromatography method.

(B) FROM FUNGAL SOURCE: ( Aspergillus niger)
⦁ Temperature of fermentation is maintained in the range 20-40 C.
⦁ Optimum pH range for production is 4.5- 8.
⦁ Fermentation period: 24- 120 hours.

Composition of production medium:

Component.                       Amount (g/L)
L-glutamic acid.                        0.3
NH4NO2.                                  1.4
K2HPO4.                                  2.0
CaCl2.                                       2.0
MgSO4.                                    0.3
Peptone.                                   7.5
FeSO4.                                     5.0
MnSO4.                                    1.6
ZnSO4.                                     1.4

Substrate: rice husk, rice bran, coir waste, wheat bran, saw dust.
C source: lactose, fructose
N source: peptone, beef extract, yeast extract
Mass production is carried out at 30 C for 96 hours in a rotary shaker at 120 rpm.

Downstream processing:
⦁ Firstly, mycelium is removed using a rotary vacuum filter
⦁ Fermented substrate is centrifuged at 6000 rpm for 15 mins and clear supernatant is used as enzyme source.
⦁ Enzyme extract is further concentrated by salt precipitation.
⦁ Finally, enzyme purification is carried out by column chromatography method.

APPLICATIONS:
⦁ In the textile Industry, cellulases have been employed for defibrillation and softening of fabrics. They are used to eliminate color variation of fibers.
⦁ In detergents and laundaries, cellulases have many important applications. They are mostly used as additives in detergents and washing powder for the breakdown of hydrogen bonding under alkaline or thermophile conditions.
⦁ Cellulases are employed in food industry to extract and clarify olive oil, fruit and vegetable juices in the production purposes and fruit nectars. In brewing industry, cellulases are used as additives for the improvement of malting of barley.
⦁ In paper and pulp industry, cellulase have been used to modify the biochemical pulping of coarse pulp and to improve strengthening. Microbial cellulases are used for the characterisation of fiber pulp.
⦁ Biofuel production: cellulases have the ability to convert lignocellulosic material into fermentable sugars like glucose, maltose, used as substrate to form bioethanol and other products.