Production of a Thermostable Extracellular Protease from Thermophilic Bacillus Species

Isolation and identification of thermophilic Bacillus sp was carried out from soil samples of a tannery area. The isolate KCPSS-3, when cultivated in liquid cultures containing trisodium citrate, produced protease. The production reached a maximum in 9 h, with levels of 2.15 U/mg protein. The microorganism utilized several carbon sources for the production of protease. Starch was found to be the best substrate, followed by trisodium citrate, citric acid and sucrose. Among the various organic and inorganic nitrogen sources used, ammonium nitrate was found to be the best. Studies on the effects of temperature and pH on protease production revealed that the Bacillus sp could grow up to 65 0C within a broad pH range of 5-10 with an optimal growth temperature and pH at 60 0C and 8.0, respectively. Thermostability studies revealed that the enzyme was stable for 2 h at 30 0C, while at 40 0C and 80 0C, 14% and 84% of the original activities were lost. Hence, it’s an indication that the enzyme produced is thermostable.