Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-Sen University, Guangzhou, China.
Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, USA.
Appl Environ Microbiol. 2020 Nov 10;86(23). doi: 10.1128/AEM.01920-20.
Pretreatment of waste-activated sludge (WAS) is an effective way to destabilize sludge floc structure and release organic matter for improving sludge digestion efficiency. Nonetheless, information on the impact of WAS pretreatment on digestion sludge microbiomes, as well as mechanistic insights into how sludge pretreatment improves digestion performance, remains elusive. In this study, a genome-centric metagenomic approach was employed to investigate the digestion sludge microbiome in four sludge digesters with different types of feeding sludge: WAS pretreated with 0.25 mol/liter alkaline/acid (APAD), WAS pretreated with 0.8 mol/liter alkaline/acid (HS-APAD), thermally pretreated WAS (thermal-AD), and fresh WAS (control-AD). We retrieved 254 metagenome-assembled genomes (MAGs) to identify the key functional populations involved in the methanogenic digestion process. These MAGs span 28 phyla, including 69 yet-to-be-cultivated lineages, and 30 novel lineages were characterized with metabolic potential associated with hydrolysis and fermentation. Interestingly, functional populations involving carbohydrate digestion were enriched in APAD and HS-APAD, while lineages related to protein and lipid fermentation were enriched in thermal-AD, corroborating the idea that different substrates are released from alkaline/acid and thermal pretreatments. Among the major functional populations (i.e., fermenters, syntrophic acetogens, and methanogens), significant correlations between genome sizes and abundance of the fermenters were observed, particularly in APAD and HS-APAD, which had improved digestion performance. Wastewater treatment generates large amounts of waste-activated sludge (WAS), which consists mainly of recalcitrant microbial cells and particulate organic matter. Though WAS pretreatment is an effective way to release sludge organic matter for subsequent digestion, detailed information on the impact of the sludge pretreatment on the digestion sludge microbiome remains scarce. Our study provides unprecedented genome-centric metagenomic insights into how WAS pretreatments change the digestion sludge microbiomes, as well as their metabolic networks. Moreover, digestion sludge microbiomes could be a unique source for exploring microbial dark matter. These results may inform future optimization of methanogenic sludge digestion and resource recovery.
预处理废活性污泥（WAS）是一种有效方法，可以破坏污泥絮体结构并释放有机物，从而提高污泥消化效率。然而，有关 WAS 预处理对消化污泥微生物组的影响，以及污泥预处理如何改善消化性能的机制见解仍然难以捉摸。在这项研究中，采用基于基因组的宏基因组方法研究了四种不同进料污泥的污泥消化器中的消化污泥微生物组：用 0.25 mol/L 碱性/酸性（APAD）预处理的 WAS、用 0.8 mol/L 碱性/酸性（HS-APAD）预处理的 WAS、热预处理的 WAS（热-AD）和新鲜 WAS（对照-AD）。我们检索了 254 个宏基因组组装基因组（MAG），以鉴定参与产甲烷消化过程的关键功能种群。这些 MAG 跨越 28 个门，包括 69 个尚未培养的谱系，并且 30 个新的谱系具有与水解和发酵相关的代谢潜力。有趣的是，涉及碳水化合物消化的功能种群在 APAD 和 HS-APAD 中富集，而与蛋白质和脂质发酵相关的谱系在热-AD 中富集，这证实了不同的底物从碱性/酸性和热预处理中释放的观点。在主要功能种群（即发酵菌、共发酵乙酸菌和产甲烷菌）中，观察到发酵菌的基因组大小与丰度之间存在显著相关性，特别是在 APAD 和 HS-APAD 中，这两种方法的消化性能得到了改善。污水处理产生大量废活性污泥（WAS），主要由难降解的微生物细胞和颗粒有机物质组成。尽管 WAS 预处理是一种有效方法，可以释放污泥有机物，以进行后续消化，但有关污泥预处理对消化污泥微生物组的影响的详细信息仍然很少。我们的研究提供了前所未有的基于基因组的宏基因组见解，了解 WAS 预处理如何改变消化污泥微生物组及其代谢网络。此外，消化污泥微生物组可能是探索微生物暗物质的独特来源。这些结果可能为优化产甲烷污泥消化和资源回收提供信息。
