Partial Purification and Characterization of Thermostable, Alkaline and Chelator-resistant Protease from a Newly Isolated Bacillus sp. CY7 and its potential applications in various industries

  • Nihan ARABACI
  • Yasemin CAF
  • Yelis MAAŞOĞLU
  • Burhan ARIKAN
Keywords: Alkali-Aggregate Reaction, Inhibitor, Slag, Silica Fume, Test Concrete Siliceous, Silica


A thermophile alkaline protease producing Bacillus sp. strains isolated from soil samples. Enzyme synthesis occurred at temperatures between 20ºC and 60ºC with an optimum of 55°C and between the pH range of 6.0-13.0 with an optimum pH of 10.0 on skimmilk agar plates. Analyses of molecular mass of the partially purified enzyme was carried out by SDS-PAGE which revealed two bands as 112 and 97 kDa. The enzyme was active in a broad temperature range between 30ºC and 100ºC, with an optimum at 70ºC, and maximum activity was at pH 11.0. The enzyme also presented the alkaline-stable properties with a remaining activity around 94%, at pH 6.0-13.0 for 24 h, at 55°C. The enzyme activity was highly stable between 30-100°C with a remaining activity 91%, after pre-incubation for 1 h. Enzyme was exposured to various NaCl concentrations (3-30%), and the highest residual activity was determined in the presence of 3% NaCl (87%). While after being exposed with β-mercaptoethanol (1%), PMSF (3mM), Tween20 (0.1%), Tween80 (0.1%), SDS (1%), TritonX100 (1%), H2O2 (1%), MnCl2 (5mM), CaCl2 (5mM), BaCl2 (5mM), MgCl (5mM), FeCl2 (5mM) and EDTA (5mM), the enzyme exhibited the following activities 105%, 101%, 107%, 119%, 72%, 99%, 98%, 98%, 99%, 98%, 97%, 97%, 96% and 99%, respectively.
According to these results, CY7 protease shows thermostable, high alkaline, alkali-stable and chelator resistant properties. Owing to its mentioned properties this protease is an ideal choice for application in detergent formulations, leather and textile industries.