School of Life Science and Biotechnology, Dalian University of Technology, Dalian 116024, China.
Appl Microbiol Biotechnol. 2013 May;97(10):4361-8. doi: 10.1007/s00253-012-4290-y. Epub 2012 Jul 21.
Xylanase is the enzyme complex that is responsible for the degradation of xylan; however, novel xylanase producers remain to be explored in marine environment. In this study, a Streptomyces strain M11 which exhibited xylanase activity was isolated from marine sediment. The 16S rDNA sequence of M11 showed the highest identity (99 %) to that of Streptomyces viridochromogenes. The xylanase produced from M11 exhibited optimum activity at pH 6.0, and the optimum temperature was 70 °C. M11 xylanase activity was stable in the pH range of 6.0-9.0 and at 60 °C for 60 min. Xylanase activity was observed to be stable in the presence of up to 5 M NaCl. Antibiotic-resistant mutants of M11 were isolated, and among the various antibiotics tested, streptomycin showed the best effect on obtaining xylanase overproducer. Mutant M11-1(10) isolated from 10 μg/ml streptomycin-containing plate showed 14 % higher xylanase activities than that of the wild-type strain. An analysis of gene rpsL (encoding ribosomal protein S12) showed that rpsL from M11-1(10) contains a K88R mutation. This is the first report to show that marine-derived S. viridochromogenes strain can be used as a xylanase producer, and utilization of ribosome engineering for the improvement of xylanase production in Streptomyces was also first successfully demonstrated.
木聚糖酶是负责降解木聚糖的酶复合物；然而，新型木聚糖酶生产菌仍有待在海洋环境中探索。在这项研究中，从海洋沉积物中分离到一株具有木聚糖酶活性的链霉菌 M11 菌株。M11 的 16S rDNA 序列与变绿链霉菌的同源性最高（99%）。M11 产生的木聚糖酶在 pH6.0 时表现出最佳活性，最适温度为 70°C。M11 木聚糖酶在 pH6.0-9.0 范围内和 60°C 下 60 分钟内稳定。木聚糖酶活性在高达 5 M NaCl 的存在下保持稳定。分离出 M11 的抗生素抗性突变体，在测试的各种抗生素中，链霉素对获得木聚糖酶高产突变体的效果最好。从含有 10 μg/ml 链霉素的平板中分离出的突变体 M11-1(10)的木聚糖酶活性比野生型菌株高 14%。对 rpsL 基因（编码核糖体蛋白 S12）的分析表明，M11-1(10)中的 rpsL 含有 K88R 突变。这是首次报道海洋来源的变绿链霉菌菌株可用作木聚糖酶生产菌，并且首次成功证明了核糖体工程在提高链霉菌木聚糖酶生产中的应用。
