Biological degradation of cellulose from dead plants in nature and plant biomass from agricultural and food-industry waste is important for sustainable carbon recirculation. This study aimed at searching diverse cellulose-degrading systems of wild filamentous fungi and obtaining fungal lines useful for cellooligosaccharide production from agro-industrial wastes. Fungal lines with cellulolytic activity were screened and isolated from stacked rice straw and soil in subtropical fields. Among 13 isolated lines, in liquid culture with a nutrition-limited cellulose-containing medium, four lines of Aspergillus spp. secreted 50–60 kDa proteins as markedly dominant components and gave clear activity bands of possible endo-β-1,4-glucanase in zymography. Mass spectroscopy (MS) analysis of the dominant components identified three endo-β-1,4-glucanases (GH5, GH7 and GH12) and two cellobiohydrolases (GH6 and GH7). Cellulose degradation by the secreted proteins was analysed by LC-MS-based measurement of derivatized reducing sugars. The enzymes from the four Aspergillus spp. produced cellobiose from crystalline cellulose and cellotriose at a low level compared with cellobiose. Moreover, though smaller than that from crystalline cellulose, the enzymes of two representative lines degraded powdered rice straw and produced cellobiose. These fungal lines and enzymes would be effective for production of cellooligosaccharides as cellulose degradation-intermediates with added value other than glucose.

中文翻译：

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Aspergillus spp在营养受限的培养基中主要分泌纤维二糖水解酶和内切β-1,4-葡聚糖酶。与亚热带领域隔离。

大自然中死植物纤维素的生物降解以及农业和食品工业废物中植物生物量的生物降解对于可持续的碳循环非常重要。这项研究旨在寻找野生丝状真菌的多种纤维素降解系统，并获得可用于从农业工业废料生产纤维寡糖的真菌系。从亚热带田间堆积的稻草和土壤中筛选并分离出具有纤维素分解活性的真菌系。在13条分离的品系中，在营养受限的含纤维素培养基的液体培养中，有4株曲霉spp。分泌的50-60 kDa蛋白是显着的主要成分，并在酶谱学中给出了可能的内切β-1,4-葡聚糖酶的清晰活性带。对主要成分的质谱（MS）分析确定了三个内切β-1,4-葡聚糖酶（GH5，GH7和GH12）和两个纤维二糖水解酶（GH6和GH7）。通过基于LC-MS的衍生还原糖的测量分析了分泌蛋白的纤维素降解。来自四种曲霉的酶spp。与纤维二糖相比，由结晶纤维素和纤维三糖生产的纤维二糖含量低。而且，尽管比来自结晶纤维素的纤维素小，但两个代表性品系的酶降解了稻草粉并产生了纤维二糖。这些真菌系和酶将有效地生产纤维素寡糖，因为纤维素降解中间物具有除葡萄糖以外的附加价值。