Department of Biochemistry, Vassyl Stefanyk Precarpathian National University, Ivano-Frankivsk, Ukraine.
Can J Microbiol. 2010 Apr;56(4):279-88. doi: 10.1139/w10-014.
As a result of screening Bacillus sp. strains isolated from different natural substrates, strain BKL20 was identified as a producer of a thermostable alkaline alpha-amylase. Maximum production of this alpha-amylase was achieved by optimizing culture conditions. Production of alpha-amylase seemed to be independent of the presence of starch in the culture medium and was stimulated by the presence of peptone (0.3%, m/v) and yeast extract (0.2%, m/v). The enzyme was thermostable and retained amylolytic activity after 30 min of incubation at 60 and 70 degrees C. High activity was maintained over a broad pH range, from 6.0 to 11.0, and the enzyme remained active after alkaline incubation for 24 h. Bacillus sp. BKL20 alpha-amylase was not stimulated by Ca2+ or other bivalent metal cations and was not inhibited by EGTA or EDTA at 1-10 mmol/L, suggesting that this alpha-amylase is a Ca2+-independent enzyme. It also showed good resistance to both oxidizing (H2O2) and denaturating (urea) agents.
从不同天然基质中分离的芽孢杆菌菌株经过筛选，发现菌株 BKL20 是一种耐热碱性α-淀粉酶的产生菌。通过优化培养条件，可以实现该α-淀粉酶的最大产量。该α-淀粉酶的产生似乎不依赖于培养基中淀粉的存在，并且受到蛋白胨（0.3%，m/v）和酵母提取物（0.2%，m/v）的刺激。该酶具有热稳定性，在 60 和 70°C 下孵育 30 分钟后仍保持淀粉酶活性。该酶在 pH 值为 6.0 至 11.0 的较宽范围内保持高活性，并且在碱性孵育 24 小时后仍保持活性。芽孢杆菌 BKL20 α-淀粉酶不受 Ca2+或其他二价金属阳离子的刺激，在 1-10 mmol/L 的 EGTA 或 EDTA 中也不受抑制，表明该α-淀粉酶是一种非依赖 Ca2+的酶。它对氧化（H2O2）和变性（尿素）试剂也具有良好的抗性。
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