Studies on production of thermostable alkaline protease from thermophilic and alkaliphilic Bacillus sp. JB-99 in a chemically defined medium
2001; Elsevier BV; Volume: 37; Issue: 2 Linguagem: Inglês
10.1016/s0032-9592(01)00191-1
ISSN1873-3298
Autores Tópico(s)Enzyme Catalysis and Immobilization
ResumoThe thermophilic and alkaliphilic Bacillus sp. JB-99 was isolated from sugarcane molasses and was cultured in 250 ml Erlenmeyer flasks containing 50 ml of synthetic medium consisting of (g/l): citric acid; 10.0, NaNO3; 10.0, K2HPO4; 5.0, MgSO4.7H2O; 0.3, CaCl2.2H2O; 0.2, NaCl; 5.0 and Na2CO3; 10.0 at pH 10.0. The cultures were incubated at 55 °C with agitation (180 rpm) for 24 h. To study the effect of different carbon and nitrogen sources on enzyme yield (U/ml): citric acid (12780), soluble starch (12480); fructose (11760) and raffinose (11650) were found best carbon sources, while NaNO3 (12780) and KNO3 were found best nitrogen sources. The optimum temperature and pH for protease activity was 70 °C and 11.0, respectively. The addition of 10 mM Ca2+ enhanced the optimum temperature 80 °C and retained 78% activity even after 1 h heat treatment at 80 °C. Proteolytic activity was completely inhibited by 1 mM PMSF and TPCK showed that it seems to be trypsin like serine alkaline protease. The enzyme activity was enhanced in the presence of 10 mM metal ions namely Mn2+, Mg2+, Cu2+ and Co2+ and activity also inhibited in the presence of 10 mM metal ions, such as Fe3+, Hg2+ and Zn2+. The enzyme was stable in the presence of 5% H2O2.
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