Production and characterization of thermotolerant-organic solvent resistant acidic protease by Pseudomonas aeruginosa RGSS-09 isolated from dairy sludge.

Fifteen bacterial strains isolated from the dairy soil samples for acidic protease production. Among them, culture RGSS-09 was adjudged as the best protease producer and was identified as Pseudomonas aeruginosa RGSS-09 from MTCC Chandigarh. The isolate showed maximum protease production (1256 U mLG) with 2.5 g LG biomass production in the presence of wheat bran and yeast extract at 37°C pH 6.5 within 48 h of incubation. Pseudomonas aeruginosa RGSS-09 also showed enhanced activity and stability in presence of Ca, Mg, Tween-20, Tween-40, triton-X-100 and SDS at 5 and 10 mM concentration. The enzyme was also stable in the presence of n-dodecane, isooctane, n-decane, xylene, toluene, n-haxane, n-butanol and cyclohexane, respectively. The presence of benzene, methanol and ethanol marginally reduced the protease stability, respectively. The enzyme was showed it 100% activity at 75°C and pH 7.5 with 110 and 100% stability at 70°C and pH 7.0, respectively. The purity of the enzyme was confirmed by the presence of a single band on SDS-PAGE and its molecular weight was approximately 42 kDa. Pseudomonas aeruginosa can be used profitably for the large scale production of protease to meet the present day demand of the industrial sector.