Biotic and abiotic factors acting on community assembly in parallel anaerobic digestion systems from a brewery wastewater treatment plant

Anaerobic digestion is a complex microbial process that mediates the transformation of organic waste into biogas. The performance and stability of anaerobic digesters relies on the structure and function of the microbial community. In this study, we asked whether the deterministic effect of wastewater composition outweighs the effect of reactor configuration on the structure and dynamics of anaerobic digester archaeal and bacterial communities. Biotic and abiotic factors acting on microbial community assembly in two parallel anaerobic digestion systems, an upflow anaerobic sludge blanket digestor (UASB) and a closed digester tank with a solid recycling system (CDSR), from a brewery WWTP were analysed utilizing 16S rDNA and <i>mcrA</i> amplicon sequencing and genome-centric metagenomics. This study confirmed the deterministic effect of the wastewater composition on bacterial community structure, while the archaeal community composition resulted better explained by organic loading rate (ORL) and volatile free acids (VFA). According to the functions assigned to the differentially abundant metagenome-assembled genomes (MAGs) between reactors, CDSR was enriched in genes related to methanol and methylamines methanogenesis, protein degradation, and sulphate and alcohol utilization. Conversely, the UASB reactor was enriched in genes associated with carbohydrate and lipid degradation, as well as amino acid, fatty acid, and propionate fermentation. By comparing interactions derived from the co-occurrence network with predicted metabolic interactions of the prokaryotic communities in both anaerobic digesters, we conclude that the overall community structure is mainly determined by habitat filtering.

厌氧消化（Anaerobic Digestion）是一类复杂的微生物过程，可介导有机废物向沼气的转化。厌氧消化反应器的性能与稳定性，依赖于微生物群落的结构与功能。本研究旨在探讨：废水组分的确定性效应是否强于反应器构型，对厌氧消化反应器中古菌与细菌群落的结构及动态变化的影响。本研究针对某啤酒厂污水处理厂（Wastewater Treatment Plant, WWTP）的两套平行厌氧消化系统展开分析：一套为升流式厌氧污泥床反应器（Upflow Anaerobic Sludge Blanket Digestor, UASB），另一套为带固体回流系统的密闭消化罐（Closed Digester Tank with a Solid Recycling System, CDSR）；研究采用16S核糖体DNA（16S rDNA）与*mcrA*扩增子测序、以基因组为中心的宏基因组学方法，解析了作用于两套系统微生物群落组装的生物与非生物因子。本研究证实，废水组分对细菌群落结构具有确定性效应，而古菌群落组成则更适合通过有机负荷率（ORL）与挥发性游离脂肪酸（VFA）进行解释。根据两套反应器间差异丰度的宏基因组组装基因组（Metagenome-Assembled Genomes, MAGs）所注释的功能，CDSR富集了与甲醇及甲胺类产甲烷、蛋白质降解、硫酸盐与醇类利用相关的基因。与之相反，UASB反应器则富集了与碳水化合物及脂质降解、氨基酸、脂肪酸与丙酸发酵相关的基因。通过对比共现网络推导的物种互作关系与两套厌氧消化系统中原核群落的预测代谢互作关系，本研究得出结论：群落整体结构主要由生境过滤作用决定。