Characterization and wash performance analysis of an SDS-stable alkaline protease from a Bacillus sp.

An alkaline, SDS-stable protease optimally active at pH 11 from a Bacillus sp. RGR-14 was produced in a complex medium containing soybean meal, starch and calcium carbonate. The protease was active over a wide temperature ran ge of 20-80 degreesC with major activity between 45 and 70 degreesC. The pr otease was completely stable for 1 h in 0.1% SDS and retained 70% of its ac tivity in the presence of 0.5% SDS after 1 h of incubation. The enzyme was active in presence of surfactants (ionic and non-ionic) with 29% enhancemen t in activity in Tween-85 and was also stable in various oxidizing agents w ith 100 and 60% activity in presence of 1% sodium perborate and 1% H2O2, re spectively. The enzyme was also compatible with commercial detergents (1% w /v) such as Surf, Ariel, Wheel, Fena and Nirma, retaining more than 70% act ivity in all the detergents after 1 h. Wash performance analysis of grass a nd blood stains on cotton fabric showed an increase in reflectance (14 and 25% with grass and blood stains, respectively) after enzyme treatment. Howe ver, enzyme in conjunction with detergent proved best, with a maximum refle ctance change of 46 and 34% for grass and blood stain removal, respectively , at 45 degreesC. Stain removal was also effective after protease treatment at 25 and 60 degreesC.