tailieunhanh - Alkaline protease production of Bacillus cohnii APT5

An obligate alkaliphilic Bacillus strain was isolated from a soil sample and identifi ed as Bacillus cohnii APT5 based upon phylogenetic and phenotypic analyses. | Turk J Biol 36 (2012) 430-440 © TÜBİTAK doi: Alkaline protease production of Bacillus cohnii APT5 Nilgün TEKİN1, Arzu ÇÖLERİ CİHAN2, Zekiye Serpil TAKAÇ3, Canan YAĞCI TÜZÜN2, Kenan TUNÇ4, Cumhur ÇÖKMÜŞ2 1 Biotechnology Institute, Ankara University, 06500 Ankara - TURKEY 2 Department of Biology, Faculty of Science, Ankara University, 06100 Tandoğan, Ankara - TURKEY 3 Department of Chemical Engineering, Faculty of Engineering, Ankara University, 06100 Tandoğan, Ankara - TURKEY 4 Department of Biology, Faculty of Arts and Sciences, Sakarya University, 54187 Esentepe, Sakarya - TURKEY Received: ● Accepted: Abstract: An obligate alkaliphilic Bacillus strain was isolated from a soil sample and identified as Bacillus cohnii APT5 based upon phylogenetic and phenotypic analyses. The optimum growth pH of B. cohnii APT5 was . B. cohnii APT5 was also found capable of producing an extracellular alkaline protease that showed optimum activity (693,318 U/min) at 50 °C and pH when grown in a medium containing casein. The enzyme was partially purified with a yield of after acetone precipitation and cation exchange column chromatography, respectively. The partially purified enzyme maintained its activity when incubated at 50 °C for 2 h. It was stable at pH at room temperature for 72 h. Furthermore, the alkaline protease activity was not completely inactivated by the specific inhibitors of serine alkaline proteases and metalloproteases such as PMSF and EDTA. While 1 mM PMSF had no effect on the enzyme activity, a 10 mM concentration of PMSF slightly decreased the activity, producing a relative activity of 76%. In addition, the enzyme was found to be very stable toward surface active agents such as SDS, Tween 20, Tween 80, and Triton X-100. None of the metal ions used (Ca2+, Mg2+, Zn2+, Fe2+, and Mn2+) showed an inhibitory effect on enzyme activity. On the contrary, APT5 alkaline protease activity .