Background Efficient deconstruction of lignocellulosic biomass into simple sugars in an economically viable manner is a prerequisite for its global acceptance as a feedstock in bioethanol production. This is achieved in nature by suites of enzymes with the capability of efficiently depolymerizing all the components of lignocellulose. Here, we provide detailed insight into the repertoire of enzymes produced by microorganisms enriched from the gut of the crop pathogen rice yellow stem borer (Scirpophaga incertulas). Results A microbial community was enriched from the gut of the rice yellow stem borer for enhanced rice straw degradation by sub-culturing every 10 days, for 1 year, in minimal medium with rice straw as the main carbon source. The enriched culture demonstrated high cellulolytic and xylanolytic activity in the culture supernatant. Metatranscriptomic and metaexoproteomic analysis revealed a large array of enzymes potentially involved in rice straw deconstruction. The consortium was found to encode genes ascribed to all five classes of carbohydrate-active enzymes (GHs, GTs, CEs, PLs, and AAs), including carbohydrate-binding modules (CBMs), categorized in the carbohydrate-active enzymes (CAZy) database. The GHs were the most abundant class of CAZymes. Predicted enzymes from these CAZy classes have the potential to digest each cell-wall components of rice straw, i.e., cellulose, hemicellulose, pectin, callose, and lignin. Several identified CAZy proteins appeared novel, having an unknown or hypothetical catalytic counterpart with a known class of CBM. To validate the findings, one of the identified enzymes that belong to the GH10 family was functionally characterized. The enzyme expressed in E. coli efficiently hydrolyzed beechwood xylan, and pretreated and untreated rice straw. Conclusions This is the first report describing the enrichment of lignocellulose degrading bacteria from the gut of the rice yellow stem borer to deconstruct rice straw, identifying a plethora of enzymes secreted by the microbial community when growing on rice straw as a carbon source. These enzymes could be important candidates for biorefineries to overcome the current bottlenecks in biomass processing.

中文翻译：

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挖掘水稻黄螟共生体的生物量解构能力。

背景以经济上可行的方式将木质纤维素生物质有效解构为单糖是其作为生物乙醇生产原料被全球接受的先决条件。这在自然界中是通过能够有效解聚木质纤维素的所有成分的酶套件来实现的。在这里，我们详细介绍了从作物病原体水稻黄螟虫 (Scirpophaga incertulas) 肠道中富集的微生物所产生的酶库。结果通过在以稻草为主要碳源的基本培养基中每10天传代培养1年，从稻黄螟的肠道中富集微生物群落以增强稻草降解。富集的培养物在培养上清液中表现出高纤维素分解和木聚糖分解活性。元转录组学和元外蛋白质组学分析揭示了大量可能参与稻草解构的酶。发现该联盟编码归于所有五类碳水化合物活性酶（GHs、GTs、CEs、PLs 和 AAs）的基因，包括碳水化合物结合模块（CBMs），归类于碳水化合物活性酶（CAZy）数据库. GH是最丰富的CAZymes类。来自这些 CAZy 类别的预测酶有可能消化稻草的每个细胞壁成分，即纤维素、半纤维素、果胶、胼胝质和木质素。几种已鉴定的 CAZy 蛋白似乎是新的，具有未知或假设的催化对应物与已知类别的 CBM。为了验证这些发现，对属于 GH10 家族的一种已鉴定酶进行了功能表征。在大肠杆菌中表达的酶可有效水解山毛榉木聚糖，以及预处理和未处理的稻草。结论 这是第一份描述从稻黄螟虫肠道中富集木质纤维素降解细菌以解构稻草的报告，确定了在稻草作为碳源上生长时微生物群落分泌的大量酶。这些酶可能是生物精炼厂克服生物质加工当前瓶颈的重要候选者。确定在稻草作为碳源上生长时微生物群落分泌的大量酶。这些酶可能是生物精炼厂克服生物质加工当前瓶颈的重要候选者。确定在稻草作为碳源上生长时微生物群落分泌的大量酶。这些酶可能是生物精炼厂克服生物质加工当前瓶颈的重要候选者。