Search

A thermophilic hydrocarbonoclastic bacterial strain Bacillus atrophaeus strain NIJ isolated from hydrocarboncontaminated soil (Algerian desert, Hassi-Messaoud petroleum region) was screened from 100 isolates because of its efficiency in maximum protease production (31,000 U/mL). A novel extracellular serine alkaline protease named SAPNIJ was purified to homogeneity using ammonium sulphate fractionation (40-70%), heat-treatment (30 min at 90 °C), and gel filtration chromatography-HPLC (ZORBAX PSM 300 HPSEC) and biochemically characterized. Its molecular mass was ~28 kDa estimated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and HPLC The NH2-terminal 27 amino-acid sequence of SAPNIJ showed high homology with those of Bacillus-proteases. The pH and temperature optimal activities were 11 and 70 °C, respectively. The phenylmethanesulfonyl fluoride (PMSF) and diiodopropyl fluorophosphates (DFP) are the specific inhibitors of SAPNIJ which confirm that it belongs to the serine-proteases family. Non-ionic surfactants and oxidizing agents are the compatibles additives of SAPNIJ as catalyzer and stabilizer. This protease showed high stability and compatibility with some commercial laundry detergents than those of Savinase™ 16L, type EX (commercial enzyme), SAPHM from Bacillus licheniformis K7A, and SAPRH from Bacillus safensis RH12. Only 500 U/mL enzyme activity cans remove blood-stains at 40 °C for 30 min. This is the first report of protease from Bacillus atrophaeus, which can be a potential promising candidate for future applications in detergent formulations. [ABSTRACT FROM AUTHOR]