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首页> 外文期刊>Applied Microbiology >Cooperative Degradation of Chitin by Extracellular and Cell Surface-Expressed Chitinases from Paenibacillus sp. Strain FPU-7
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Cooperative Degradation of Chitin by Extracellular and Cell Surface-Expressed Chitinases from Paenibacillus sp. Strain FPU-7

机译：胞外和细胞表面表达的几丁质酶从Paenibacillus sp。合作降解甲壳质。应变FPU-7

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Chitin, a major component of fungal cell walls and invertebrate cuticles, is an exceedingly abundant polysaccharide, ranking next to cellulose. Industrial demand for chitin and its degradation products as raw materials for fine chemical products is increasing. A bacterium with high chitin-decomposing activity, Paenibacillus sp. strain FPU-7, was isolated from soil by using a screening medium containing α-chitin powder. Although FPU-7 secreted several extracellular chitinases and thoroughly digested the powder, the extracellular fluid alone broke them down incompletely. Based on expression cloning and phylogenetic analysis, at least seven family 18 chitinase genes were found in the FPU-7 genome. Interestingly, the product of only one gene ( chiW ) was identified as possessing three S-layer homology (SLH) domains and two glycosyl hydrolase family 18 catalytic domains. Since SLH domains are known to function as anchors to the Gram-positive bacterial cell surface, ChiW was suggested to be a novel multimodular surface-expressed enzyme and to play an important role in the complete degradation of chitin. Indeed, the ChiW protein was localized on the cell surface. Each of the seven chitinase genes ( chiA to chiF and chiW ) was cloned and expressed in Escherichia coli cells for biochemical characterization of their products. In particular, ChiE and ChiW showed high activity for insoluble chitin. The high chitinolytic activity of strain FPU-7 and the chitinases may be useful for environmentally friendly processing of chitin in the manufacture of food and/or medicine.
机译：几丁质是真菌细胞壁和无脊椎动物角质层的主要成分，是一种极其丰富的多糖，仅次于纤维素。对几丁质及其降解产物作为精细化工产品原料的工业需求正在增加。一种具有高几丁质分解活性的细菌，Paenibacillus sp.。通过使用含有α-几丁质粉末的筛选培养基从土壤中分离出菌株FPU-7。尽管FPU-7分泌了几种胞外几丁质酶并彻底消化了粉末，但仅胞外液就不能完全分解它们。根据表达克隆和系统发育分析，在FPU-7基因组中至少发现7个18号几丁质酶基因。有趣的是，仅一个基因的产物（chiW）被鉴定为具有三个S层同源性（SLH）域和两个糖基水解酶家族18个催化域。由于已知SLH结构域可充当革兰氏阳性细菌细胞表面的锚，因此ChiW被认为是一种新型的多模块表面表达酶，并且在几丁质的完全降解中起着重要作用。实际上，ChiW蛋白位于细胞表面。克隆了七个几丁质酶基因（chiA至chiF和chiW），并在大肠杆菌细胞中表达，以对其产物进行生化鉴定。特别地，ChiE和ChiW显示出对不溶性几丁质的高活性。 FPU-7菌株和几丁质酶的高几丁质分解活性可用于食品和/或药物生产中几丁质的环保加工。

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