Thomas Lebin, Ram Hari, Singh Ved Pal
University of Delhi, Department of Botany, Delhi, India.
University of Delhi, Department of Botany, Delhi, India.
Braz J Microbiol. 2018 Apr-Jun;49(2):429-442. doi: 10.1016/j.bjm.2017.05.010. Epub 2017 Nov 6.
Bacteria are important sources of cellulases with various industrial and biotechnological applications. In view of this, a non-hemolytic bacterial strain, tolerant to various environmental pollutants (heavy metals and organic solvents), showing high cellulolytic index (7.89) was isolated from cattle shed soil and identified as Bacillus sp. SV1 (99.27% pairwise similarity with Bacillus korlensis). Extracellular cellulases showed the presence of endoglucanase, total cellulase and β-glucosidase activities. Cellulase production was induced in presence of cellulose (3.3 times CMCase, 2.9 times FPase and 2.1 times β-glucosidase), and enhanced (115.1% CMCase) by low-cost corn steep solids. An in silico investigation of endoglucanase (EC 3.2.1.4) protein sequences of three Bacillus spp. as query, revealed their similarities with members of nine bacterial phyla and to Eukaryota (represented by Arthropoda and Nematoda), and also highlighted of a convergent and divergent evolution from other enzymes of different substrate [(1,3)-linked beta-d-glucans, xylan and chitosan] specificities. Characteristic conserved signature indels were observed among members of Actinobacteria (7 aa insert) and Firmicutes (9 aa insert) that served as a potential tool in support of their relatedness in phylogenetic trees.
细菌是具有各种工业和生物技术应用的纤维素酶的重要来源。鉴于此，从牛棚土壤中分离出一株对各种环境污染物（重金属和有机溶剂）具有耐受性、非溶血的细菌菌株，其纤维素分解指数较高（7.89），并被鉴定为芽孢杆菌属SV1（与科氏芽孢杆菌的成对相似性为99.27%）。胞外纤维素酶显示存在内切葡聚糖酶、总纤维素酶和β-葡萄糖苷酶活性。在纤维素存在的情况下诱导产生纤维素酶（CMCase为3.3倍、FPase为2.9倍、β-葡萄糖苷酶为2.1倍），并通过低成本的玉米浆固体使其产量提高（CMCase提高115.1%）。以三种芽孢杆菌属的内切葡聚糖酶（EC 3.2.1.4）蛋白质序列作为查询进行的计算机模拟研究表明，它们与九个细菌门的成员以及真核生物（以节肢动物和线虫为代表）具有相似性，并且还突出显示了与具有不同底物特异性的其他酶（[(1,3)-连接的β-D-葡聚糖、木聚糖和壳聚糖]）的趋同和趋异进化。在放线菌（7个氨基酸插入）和厚壁菌门（9个氨基酸插入）的成员中观察到特征性保守特征插入缺失，这在系统发育树中作为支持它们亲缘关系的潜在工具。
