Malhotra R, Noorwez S M, Satyanarayana T
Department of Microbiology, University of Delhi South Campus, New Delhi, India.
Lett Appl Microbiol. 2000 Nov;31(5):378-84. doi: 10.1046/j.1472-765x.2000.00830.x.
An investigation was carried out on the production of alpha-amylase by Bacillus thermooleovorans NP54, its partial purification and characterization.
The thermophilic bacterium was grown in shake flasks and a laboratory fermenter containing 2% soluble starch, 0.3% tryptone, 0.3% yeast extract and 0.1% K2HPO4 at 70 degrees C and pH 7.0, agitated at 200 rev min(-1) with 6-h-old inoculum (2% v/v) for 12 h. When the enzyme was partially purified using acetone (80%[v/v] saturation), a 43.7% recovery of enzyme with 6.2-fold purification was recorded. The KM and Vmax (soluble starch) values were 0.83 mg ml(-1) and 250 micromol mg(-1) protein min(-1), respectively. The enzyme was optimally active at 100 degrees C and pH 8.0 with a half-life of 3 h at 100 degrees C. Both alpha-amylase activity and production were Ca2+ independent.
Bacillus thermooleovorans NP54 produced calcium-independent and thermostable alpha-amylase.
The calcium-independent and thermostable alpha-amylase of B. thermooleovorans NP54 will be extremely useful in starch saccharification since the alpha-amylases used in the starch industry are calcium dependent. The use of this enzyme in starch hydrolysis eliminates the use of calcium in starch liquefaction and subsequent removal by ion exchange.
对嗜热油栖芽孢杆菌NP54产生α-淀粉酶、其部分纯化及特性进行研究。
嗜热菌在摇瓶和实验室发酵罐中培养，发酵罐中含有2%可溶性淀粉、0.3%胰蛋白胨、0.3%酵母提取物和0.1%磷酸氢二钾，于70℃、pH 7.0条件下，以6小时龄接种物（2% v/v）在200转/分钟搅拌培养12小时。当用丙酮（80%[v/v]饱和度）对酶进行部分纯化时，酶回收率为43.7%，纯化倍数为6.2倍。米氏常数（KM）和最大反应速度（Vmax，针对可溶性淀粉）值分别为0.83毫克/毫升和250微摩尔/毫克蛋白质·分钟。该酶在100℃和pH 8.0时活性最佳，在100℃下半衰期为3小时。α-淀粉酶活性和产量均不依赖钙离子。
嗜热油栖芽孢杆菌NP54产生不依赖钙离子且耐热的α-淀粉酶。
嗜热油栖芽孢杆菌NP54的不依赖钙离子且耐热的α-淀粉酶在淀粉糖化方面将非常有用，因为淀粉工业中使用的α-淀粉酶依赖钙离子。在淀粉水解中使用这种酶可避免在淀粉液化过程中使用钙离子以及随后通过离子交换去除钙离子。
