BACKGROUND Sugarcane bagasse is a major source of lignocellulosic biomass, yet its economic potential is not fully realised. To add value to bagasse, processing is needed to gain access to the embodied recalcitrant biomaterials. When bagasse is stored in piles in the open for long periods it is colonised by microbes originating from the sugarcane, the soil nearby or spores in the environment. For these microorganisms to proliferate they must digest the bagasse to access carbon for growth. The microbial community in bagasse piles is thus a potential resource for the discovery of useful and novel microbes and industrial enzymes. We used culturing and metabarcoding to understand the diversity of microorganisms found in a uniquely undisturbed bagasse storage pile and screened the cultured organisms for fibre-degrading enzymes. RESULTS Samples collected from 60 to 80 cm deep in the bagasse pile showed hemicellulose and partial lignin degradation. One hundred and four microbes were cultured from different layers and included a high proportion of oleaginous yeast and biomass-degrading fungi. Overall, 70, 67, 70 and 57% of the microbes showed carboxy-methyl cellulase, xylanase, laccase and peroxidase activity, respectively. These percentages were higher in microbes selectively cultured from deep layers, with all four activities found for 44% of these organisms. Culturing and amplicon sequencing showed that there was less diversity and therefore more selection in the deeper layers, which were dominated by thermophiles and acid tolerant organisms, compared with the top of pile. Amplicon sequencing indicated that novel fungi were present in the pile. CONCLUSIONS A combination of culture-dependent and independent methods was successful in exploring the diversity in the bagasse pile. The variety of species that was found and that are known for biomass degradation shows that the bagasse pile was a valuable selective environment for the identification of new microbes and enzymes with biotechnological potential. In particular, lignin-modifying activities have not been reported previously for many of the species that were identified, suggesting future studies are warranted.

中文翻译：

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未受干扰的甘蔗渣堆中微生物多样性和功能的快照。


背景技术甘蔗渣是木质纤维素生物质的主要来源，但其经济潜力尚未完全实现。为了增加甘蔗渣的价值，需要进行加工以获得所含的顽固生物材料。当甘蔗渣长期露天堆放时，来自甘蔗、附近土壤或环境中孢子的微生物就会在其中定殖。为了使这些微生物增殖，它们必须消化甘蔗渣以获取生长所需的碳。因此，甘蔗渣堆中的微生物群落是发现有用的新型微生物和工业酶的潜在资源。我们使用培养和元条形码来了解在独特的未受干扰的甘蔗渣储存堆中发现的微生物的多样性，并筛选培养的生物体中的纤维降解酶。结果 从甘蔗渣堆中 60 至 80 厘米深处收集的样品显示半纤维素和部分木质素降解。从不同层培养了一百零四种微生物，其中包括高比例的产油酵母和生物量降解真菌。总体而言，70%、67%、70% 和 57% 的微生物分别表现出羧甲基纤维素酶、木聚糖酶、漆酶和过氧化物酶活性。在从深层选择性培养的微生物中，这些百分比更高，其中 44% 的微生物具有所有四种活性。培养和扩增子测序表明，与堆顶部相比，较深层的多样性较少，因此有更多的选择，这些层以嗜热菌和耐酸生物为主。扩增子测序表明该堆中存在新的真菌。结论 依赖培养和独立培养方法的结合成功地探索了甘蔗渣堆的多样性。 已发现的各种以生物量降解而闻名的物种表明，甘蔗渣堆是鉴定具有生物技术潜力的新微生物和酶的宝贵选择环境。特别是，许多已确定的物种的木质素改性活性此前尚未报道，这表明未来的研究是有必要的。