Department of Agricultural Science, Graduate School of Sustainability Science, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan.
Department of Agricultural, Life and Environmental Sciences, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan.
FEMS Microbiol Lett. 2020 Apr 1;367(7). doi: 10.1093/femsle/fnaa055.
Cellulosimicrobium sp. NTK2 (NTK2 strain) was isolated as a chitinolytic bacterium from mature compost derived from chitinous waste. The growth of the NTK2 strain was enhanced by supplementation of the culture medium with 2% crystalline chitin. Approximately 70% of the supplemented crystalline chitin was degraded during cultivation. Whole genome analysis of the NTK2 strain identified eight chitinases and two chitin-binding proteins. The NTK2 strain secreted two bacterial extracellular solute-binding proteins, three family 18 glycosyl hydrolases and one lytic polysaccharide monooxygenase specifically in the presence of crystalline chitin. A chitinolytic enzyme with a molecular mass of 29 kDa on SDS-PAGE under native conditions was also secreted. This chitinolytic enzyme exhibited the largest band upon zymography but could not be identified. In an attempt to identify all the chitinases secreted by the NTK2 strain, we expressed recombinant versions of the proteins exhibiting chitinolytic activity in Escherichia coli. Our results suggest that the 29 kDa protein belonging to family 19 glycosyl hydrolase was expressed specifically in the presence of 2% crystalline chitin.
从来源于几丁质废物的成熟堆肥中分离到的产几丁质分解菌为纤维微菌属 sp. NTK2（NTK2 菌株）。在培养基中添加 2%结晶几丁质可增强 NTK2 菌株的生长。在培养过程中，约 70%的补充结晶几丁质被降解。对 NTK2 菌株的全基因组分析鉴定出了 8 种几丁酶和 2 种几丁质结合蛋白。NTK2 菌株在存在结晶几丁质的情况下特异性地分泌两种细菌细胞外溶质结合蛋白、三种家族 18 糖苷水解酶和一种溶菌多糖单加氧酶。在天然条件下 SDS-PAGE 上分子量为 29 kDa 的几丁质酶也被分泌出来。该几丁质酶在酶谱中表现出最大的条带，但无法鉴定。为了鉴定 NTK2 菌株分泌的所有几丁酶，我们在大肠杆菌中表达了具有几丁质水解活性的蛋白的重组版本。我们的结果表明，属于家族 19 糖苷水解酶的 29 kDa 蛋白是在 2%结晶几丁质存在的情况下特异性表达的。
