Soares Valeria F, Castilho Leda R, Bon Elba P S, Freire Denise M G
Department of Biochemistry, Institute of Chemistry, Federal University of Rio de Janeiro, Brazil.
Appl Biochem Biotechnol. 2005 Spring;121-124:311-9. doi: 10.1385/abab:121:1-3:0311.
A Bacillus subtilis isolate was shown to be able to produce extracellular protease in solid-state fermentations (SSF) using soy cake as culture medium. A significant effect of inoculum concentration and physiological age on pro tease production was observed. Maximum activities were obtained for inocula consisting of exponentially growing cells at inoculum concentrations in the range of 0.7-2.0 mg g(-1). A comparative study on the influence of cultivation temperature and initial medium pH on protease production in SSF and in submerged fermentation (SF) revealed that in SSF a broader pH range (5-10), but the same optimum temperature (37 degrees C), is obtained when compared to SF. A kinetic study showed that enzyme production is associated with bacterial growth and that enzyme inactivation begins before biomass reaches a maximum level for both SF and SSF. Maximum protease activity and productivity were 960 U g(-1) and 15.4 U g-1 h-1 for SSF, and 12 U mL-1 and 1.3 U mL-1 h-1 for SF. When SSF protease activity was expressed by volume of enzyme extract, the enzyme level was 10-fold higher and the enzyme productivity 45% higher than in SF. These results indicate that this bacterial strain shows a high biotechnological potential for protease production in solid-state fermentation.
一株枯草芽孢杆菌被证明能够以豆饼为培养基，通过固态发酵（SSF）产生胞外蛋白酶。观察到接种浓度和生理年龄对蛋白酶产生有显著影响。对于由处于指数生长期的细胞组成的接种物，接种浓度在0.7 - 2.0 mg g(-1)范围内时可获得最大活性。一项关于培养温度和初始培养基pH对固态发酵和深层发酵（SF）中蛋白酶产生影响的比较研究表明，与深层发酵相比，固态发酵可获得更宽的pH范围（5 - 10），但最适温度相同（37℃）。动力学研究表明，酶的产生与细菌生长相关，并且对于深层发酵和固态发酵，酶失活在生物量达到最大水平之前就开始了。固态发酵的最大蛋白酶活性和生产率分别为960 U g(-1)和15.4 U g-1 h-1，深层发酵的分别为12 U mL-1和1.3 U mL-1 h-1。当以酶提取物的体积来表示固态发酵的蛋白酶活性时，酶水平比深层发酵高10倍，酶生产率比深层发酵高45%。这些结果表明，该菌株在固态发酵中具有生产蛋白酶的高生物技术潜力。
