Planta Piloto de Procesos Industriales Microbiológicos PROIMI-CONICET, Av. Belgrano Y Pasaje Caseros, T4001 MVB, 4000, San Miguel de Tucumán, Argentina.
Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, San Miguel de Tucumán, Argentina.
Appl Microbiol Biotechnol. 2021 Sep;105(18):6759-6778. doi: 10.1007/s00253-021-11495-5. Epub 2021 Aug 30.
The genus Cohnella belongs to a group of Gram-positive endospore-forming bacteria within the Paenibacillaceae family. Although most species were described as xylanolytic bacteria, the literature still lacks some key information regarding their repertoire of xylan-degrading enzymes. The whole genome sequence of an isolated xylan-degrading bacterium Cohnella sp. strain AR92 was found to contain five genes encoding putative endo-1,4-β-xylanases, of which four were cloned, expressed, and characterized to better understand the contribution of the individual endo-xylanases to the overall xylanolytic properties of strain AR92. Three of the enzymes, CoXyn10A, CoXyn10C, and CoXyn11A, were shown to be effective at hydrolyzing xylans-derived from agro-industrial, producing oligosaccharides with substrate conversion values of 32.5%, 24.7%, and 10.6%, respectively, using sugarcane bagasse glucuronoarabinoxylan and of 29.9%, 19.1%, and 8.0%, respectively, using wheat bran-derived arabinoxylan. The main reaction products from GH10 enzymes were xylobiose and xylotriose, whereas CoXyn11A produced mostly xylooligosaccharides (XOS) with 2 to 5 units of xylose, often substituted, resulting in potentially prebiotic arabinoxylooligosaccharides (AXOS). The endo-xylanases assay displayed operational features (temperature optima from 49.9 to 50.4 °C and pH optima from 6.01 to 6.31) fitting simultaneous xylan utilization. Homology modeling confirmed the typical folds of the GH10 and GH11 enzymes, substrate docking studies allowed the prediction of subsites (- 2 to + 1 in GH10 and - 3 to + 1 in GH11) and identification of residues involved in ligand interactions, supporting the experimental data. Overall, the Cohnella sp. AR92 endo-xylanases presented significant potential for enzymatic conversion of agro-industrial by-products into high-value products.Key points• Cohnella sp. AR92 genome encoded five potential endo-xylanases.• Cohnella sp. AR92 enzymes produced xylooligosaccharides from xylan, with high yields.• GH10 enzymes from Cohnella sp. AR92 are responsible for the production of X2 and X3 oligosaccharides.• GH11 from Cohnella sp. AR92 contributes to the overall xylan degradation by producing substituted oligosaccharides.
科恩氏菌属属于芽孢杆菌科的一组革兰氏阳性产芽孢内生细菌。尽管大多数物种被描述为木聚糖分解菌，但文献中仍缺乏一些关于其木聚糖降解酶谱的关键信息。从一株可降解木聚糖的细菌科恩氏菌属菌株 AR92 中分离出的全基因组序列发现，它含有五个编码潜在的内切-1,4-β-木聚糖酶的基因，其中四个被克隆、表达和表征，以更好地了解单个内切木聚糖酶对菌株 AR92 整体木聚糖降解特性的贡献。这三种酶，CoXyn10A、CoXyn10C 和 CoXyn11A，在水解来自农业-工业的木聚糖时非常有效，使用甘蔗渣葡甘露聚糖和麦麸阿拉伯木聚糖作为底物，分别产生 32.5%、24.7%和 10.6%的寡糖转化率，以及 29.9%、19.1%和 8.0%的转化率。GH10 酶的主要反应产物是木二糖和木三糖，而 CoXyn11A 主要产生 2 到 5 个木糖单位的木寡糖（XOS），通常是取代的，从而产生潜在的益生元阿拉伯木寡糖（AXOS）。内切木聚糖酶的测定显示出操作特性（49.9 至 50.4°C 的最佳温度和 6.01 至 6.31 的最佳 pH 值），适合同时利用木聚糖。同源建模证实了 GH10 和 GH11 酶的典型折叠，底物对接研究允许预测亚位点（GH10 中的-2 至+1 和 GH11 中的-3 至+1）和鉴定参与配体相互作用的残基，支持实验数据。总的来说，科恩氏菌属 AR92 的内切木聚糖酶具有将农业-工业副产品转化为高价值产品的巨大潜力。
关键点
科恩氏菌属 AR92 基因组编码五个潜在的内切木聚糖酶。
科恩氏菌属 AR92 酶从木聚糖中产生具有高得率的木寡糖。
GH10 酶是科恩氏菌属 AR92 产生 X2 和 X3 寡糖的关键。
GH11 酶有助于通过产生取代的寡糖来促进整体木聚糖的降解。
