title: Detergent-compatible, organic solvent-tolerant alkaline protease from Bacillus circulans MTCC 7942: Purification and characterization.
abstract: Proteases are now recognized as the most indispensable industrial biocatalyst owing to their diverse microbial sources and innovative applications. In the present investigation, a thermostable, organic solvent-tolerant, alkaline serine protease from Bacillus circulans MTCC 7942, was purified and characterized. The protease was purified to 37-fold by a three-step purification scheme with 39% recovery. The optimum pH and temperature for protease was 10 and 60 °C, respectively. The apparent molecular mass of the purified enzyme was 43 kD as revealed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The Km and Vmax values using casein-substrate were 3.1 mg/mL and 1.8 µmol/min, respectively. The protease remained stable in the presence of organic solvents with higher (>3.2) log P value (cyclohexane, n-octane, n-hexadecane, n-decane, and n-dodecane), as compared to organic solvents with lower (<3.2) log P value (acetone, butanol, benzene, chloroform, toluene). Remarkably, the protease showed profound stability even in the presence of organic solvents with less log P values (glycerol, dimethyl sulfate [DMSO], p-xylene), indicating the possibility of nonaqueous enzymatic applications. Also, protease activity was improved in the presence of metal ions (Ca(2+), Mg(2+), Mn(2+)); enhanced by biosurfactants; hardly affected by bleaching agents, oxidizing agents, and chemical surfactants; and stable in commercial detergents. In addition, a protease-detergent formulation effectively washed out egg and blood stains as compared to detergent alone. The protease was suitable for various commercial applications like processing of gelatinous film and as a compatible additive to detergent formulation with its operative utility in hard water.
authors.affiliation: a Department of Microbiology , R. C. Patel A. C. S. College , Shirpur , India.
authors.forename: Ulhas
authors.initials: U
authors.lastname: Patil
authors.affiliation: a Department of Microbiology , R. C. Patel A. C. S. College , Shirpur , India.
authors.forename: Narendra
authors.initials: N
authors.lastname: Mokashe
authors.affiliation: b School of Life Sciences , North Maharashtra University , Jalgaon , India.
authors.forename: Ambalal
authors.initials: A
authors.lastname: Chaudhari
mesh_terms: D001407:Bacillus / Q000201:enzymology*; D001426:Bacterial Proteins / Q000302:isolation & purification / Q000378:metabolism*; D003902:Detergents / Q000737:chemistry*; D010450:Endopeptidases / Q000302:isolation & purification / Q000378:metabolism*; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009930:Organic Chemicals / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry*; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D003902:Detergents; D009930:Organic Chemicals; D012997:Solvents; D010450:Endopeptidases; C087822:alkaline protease
keywords: Alkaline protease; Bacillus circulans; X-ray film; biosurfactant; detergent; organic solvent