Immobilization of Bacillus subtilis enzymes living on the surface of cotton

Nitrogen source	α-amylase (µmL-1)+SE
Growth(Optical Density at 600 nm) + SE
Ammonium sulphate	0,021±0,0006	0,01±0,0007
Ammonium chloride	0,043±0,003	0,04±0,003
Ammonium nitrate	1,34±0,0287	0,29±0,0217
Potassium nitrate	1,52±0,047	0,31±0,023
Tryptone	0,787±0,0169	0,181±0,013
Peptone	2,71±0,0344	0,587±0,044
Beef extract	2,4±0,0877	0,485±0,036
Yeast extract	1,72±0,025	0,378±0,0284
Peptone+Beef extract	1,89±0,0488	0,423±0,0317

Tab.2. Effect of different nitrogen sources on –amylase production and growth of Bacillus subtilis

 

III.2. Effect of sodium alginate concentration during immobilization in alginate gel

It has been reported that the immobilization yield of enzyme depends on concentration of sodium alginate [19], the porosity of the calcium alginate beads depend upon the alginate type and the gelling agent concentration [25]. Various concentrations of sodium alginate were used for preparation of calcium alginate beads in order to vary the relative degree of cross linking which would create different pore size. The immobilization yield was found to be highest (90%) for a final sodium alginate concentration of 3% (w/v) (Fig. 9).

III.3. Effect of concentration calcium chloride during immobilization in alginate gel

Concentration of calcium chloride was also varied in order to acquire stable beads capable to secure maximum enzyme. It was found that 1M calcium chloride retained highest (89%) α-amylase and as the concentration of calcium chloride increased beyond 1M, immobilization yield of α-amylase was decreased (Fig.10). A decrease in the relative protease activity with increase in calcium chloride concentration has been reported [27, 28]. It might be due to change in pH of calcium