Enzyme Technology Laboratory, Bioresources Technology Unit, National Center for Genetic Engineering and Biotechnology (BIOTEC), 113 Thailand Science Park, Paholyothin Road, Klong Luang, Pathumthani, 12120, Thailand.
Microb Ecol. 2013 Aug;66(2):322-34. doi: 10.1007/s00248-013-0209-0. Epub 2013 Mar 17.
Industrial bagasse collection sites at sugar mills are an important resource for biomass-based industries and represent a unique ecological niche in lignocellulose degradation. In this study, microbial community structures at regions with varying microenvironmental conditions contained within a bagasse collection site were explored using tagged 16S rRNA gene pyrosequencing. Overall, remarkable differences in microbial community structures were found in aerobic surface and oxygen-limited interior regions of the pile. A variety of Alphaproteobacteria and Gammaproteobacteria represented the majority of bacteria in the aerobic upper-pile regions with the predominance of acetic acid bacteria towards the outer surface. Diverse Proteobacteria, Bacteroidetes, and Acidobacteria represented the predominant phyla at the exterior soil-contact pile base with an increasing abundance of anaerobic Spirochaetes with the increasing depth, where it shared similar community structures to that in the open-field soil from decomposed bagasse. Using complementary shotgun pyrosequencing, a variety of genes encoding various glycosyl hydrolases targeting cellulose and hemicellulose degradation were identified in the oxygen-limited interior pile base. Most were relevant to orders Clostridiales, Bacteroidales, Sphingobacteriales, and Cytophagales, suggesting their role in lignocellulose degradation in this region, as evidenced by the decrease in cellulose and respective increase in lignin fractions of the biomass. Partial carbon flux in the anoxic region was metabolized through mixed methanogenesis pathways as suggested by the annotated functional genes in methane synthesis. This study gives insights into native microbial community structures and functions in this unique lignocellulose degrading environment and provides the basis for controlling microbial processes important for utilization of bagasse in bio-industries.
糖厂的工业蔗渣收集点是生物质基工业的重要资源，代表了木质纤维素降解中独特的生态位。在这项研究中，使用标记的 16S rRNA 基因焦磷酸测序技术，探索了蔗渣收集点内具有不同微环境条件的区域的微生物群落结构。总的来说，在有氧表面和堆内部的缺氧区域中，微生物群落结构存在显著差异。在有氧上堆区域中，大多数细菌由 Alphaproteobacteria 和 Gammaproteobacteria 组成，而在外层表面则以醋酸菌为主。在外部土壤接触堆底的主要菌群为 Proteobacteria、Bacteroidetes 和 Acidobacteria，随着深度的增加，厌氧菌 Spirochaetes 的丰度增加，与分解蔗渣的野外土壤具有相似的群落结构。使用互补的 shotgun 焦磷酸测序技术，在缺氧堆底中鉴定出了多种编码针对纤维素和半纤维素降解的各种糖苷水解酶的基因。大多数与 Clostridiales、Bacteroidales、Sphingobacteriales 和 Cytophagales 目相关，这表明它们在该区域木质纤维素降解中的作用，正如生物质中纤维素的减少和木质素部分的相应增加所证明的那样。缺氧区域的部分碳通量通过混合产甲烷途径代谢，这正如甲烷合成中注释的功能基因所表明的那样。这项研究深入了解了这种独特的木质纤维素降解环境中的天然微生物群落结构和功能，并为控制在生物工业中利用蔗渣的微生物过程提供了基础。
