Uma Maheswar Rao J L, Satyanarayana T
Department of Microbiology, University of Delhi South Campus, Benito Juarez Road, New Delhi, India.
J Appl Microbiol. 2003;95(4):712-8. doi: 10.1046/j.1365-2672.2003.02036.x.
Statistical optimization for maximum production of a hyperthermostable, Ca2+-independent and high maltose-forming alpha-amylase by Geobacillus thermoleovorans.
G. thermoleovorans was cultivated in 250 ml flasks containing 50 ml of chemically defined glucose-arginine medium (g l(-1): glucose 20; arginine 1.2; riboflavin 150 microg ml(-1); MgSO4. 7H2O 0.2; NaCl 1.0; pH 7.0). The medium was inoculated with 5 h-old bacterial inoculum (1.8x10(8) CFU ml(-1)), and incubated in an incubator shaker at 70 degrees C for 12 h at 200 rev min(-1). The fermentation variables optimized by 'one variable at a time' approach were further optimized by response surface methodology (RSM). The statistical model was obtained using central composite design (CCD) with three variables: glucose, riboflavin and inoculum density. An over all 24 and 70% increase in enzyme production was attained in shake flasks and fermenter because of optimization by RSM, respectively. A good coverage of interactions could also be explained by RSM. The end products of the action of alpha-amylase on starch were maltose (62%), maltotriose (31%) and malto-oligosaccharides (7%).
RSM allowed optimization of medium components and cultural parameters for attaining high yields of alpha-amylase, and further, a good coverage of interactions could be explained. The yield of maltose was higher than maltotriose and malto-oligosaccharides in the starch hydrolysate.
By applying RSM, critical fermentation variables were optimized rapidly. The starch hydrolysate contained a high proportion of maltose, and therefore, the enzyme can find application in starch saccharification process for the manufacture of high maltose syrups. The use of this enzyme in starch saccharification eliminates the addition of Ca2+.
对嗜热栖热芽孢杆菌产生超嗜热、不依赖Ca2+且高产麦芽糖的α-淀粉酶进行统计优化以实现最大产量。
嗜热栖热芽孢杆菌在装有50 ml化学限定葡萄糖-精氨酸培养基（g l(-1)：葡萄糖20；精氨酸1.2；核黄素150 μg ml(-1)；MgSO4·7H2O 0.2；NaCl 1.0；pH 7.0）的250 ml烧瓶中培养。用5小时龄的细菌接种物（1.8×10(8) CFU ml(-1)）接种培养基，并在70℃的恒温摇床中以200转/分钟培养12小时。通过“一次一个变量”方法优化的发酵变量通过响应面法（RSM）进一步优化。使用包含葡萄糖、核黄素和接种密度三个变量的中心复合设计（CCD）获得统计模型。由于通过RSM进行优化，摇瓶和发酵罐中的酶产量分别总体提高了24%和70%。RSM也可以解释相互作用的良好覆盖情况。α-淀粉酶作用于淀粉的终产物为麦芽糖（62%）、麦芽三糖（31%）和麦芽寡糖（7%）。
RSM能够优化培养基成分和培养参数以实现α-淀粉酶的高产，并且可以解释相互作用的良好覆盖情况。淀粉水解产物中麦芽糖的产量高于麦芽三糖和麦芽寡糖。
通过应用RSM，关键发酵变量得以快速优化。淀粉水解产物中麦芽糖比例较高，因此，该酶可用于淀粉糖化过程以生产高麦芽糖糖浆。在淀粉糖化中使用这种酶可避免添加Ca2+。
