Center for Microbial Communities, Department of Chemistry and Bioscience, Aalborg University, 9220 Aalborg, Denmark; Key Laboratory of Engineering Oceanography, Second Institute of Oceanography, SOA, Hangzhou, 310012, China.
Center for Microbial Communities, Department of Chemistry and Bioscience, Aalborg University, 9220 Aalborg, Denmark; Centre for Microbiome Research, School of Biomedical Sciences, Queensland University of Technology (QUT), Translational Research Institute, Woolloongabba, Australia.
Water Res. 2021 Mar 1;191:116779. doi: 10.1016/j.watres.2020.116779. Epub 2020 Dec 23.
Foaming is a common operational problem in anaerobic digestion (AD) systems, where hydrophobic filamentous microorganisms are usually considered to be the major cause. However, little is known about the identity of foam-stabilising microorganisms in AD systems, and control measures are lacking. This study identified putative foam forming microorganisms in 13 full-scale mesophilic digesters located at 11 wastewater treatment plants in Denmark, using 16S rRNA gene amplicon sequencing with species-level resolution and fluorescence in situ hybridization (FISH) for visualization. A foaming potential aeration test was applied to classify the digester sludges according to their foaming propensity. A high foaming potential for sludges was linked to the abundance of species from the genus Candidatus Microthrix, immigrating with the feed stream (surplus activated sludge), but also to several novel phylotypes potentially growing in the digester. These species were classified to the genera Ca. Brevefilum (Ca. B. fermentans) and Tetrasphaera (midas_s_5), the families ST-12K33 (midas_s_22), and Rikenellaceae (midas_s_141), and the archaeal genus Methanospirillum (midas_s_2576). Application of FISH showed that these potential foam-forming organisms all had a filamentous morphology. Additionally, it was shown that concentrations of ammonium and total nitrogen correlated strongly to the presence of foam-formers. This study provided new insight into the identity of putative foam-forming microorganisms in mesophilic AD systems, allowing for the subsequent surveillance of their abundances and studies of their ecology. Such information will importantly inform the development of control measures for these problematic microorganisms.
起泡是厌氧消化（AD）系统中常见的运行问题，通常认为疏水性丝状微生物是主要原因。然而，对于 AD 系统中稳定泡沫的微生物的身份知之甚少，并且缺乏控制措施。本研究使用 16S rRNA 基因扩增子测序（具有种水平分辨率）和荧光原位杂交（FISH）可视化，在丹麦的 11 个污水处理厂的 13 个中试规模的嗜热消化器中鉴定了潜在的泡沫形成微生物。通过应用起泡潜力曝气试验，根据其起泡倾向对消化器污泥进行分类。污泥的高起泡潜力与进料流（剩余活性污泥）中的属假微单胞菌（Ca. Microthrix）的丰度有关，但也与几个可能在消化器中生长的新的生物型有关。这些物种被分类为短杆菌属（Ca. B. fermentans）和 Tetrasphaera 属、ST-12K33 科（midas_s_22）和 Rikenellaceae 科（midas_s_141）以及古菌甲烷螺旋菌属（midas_s_2576）。FISH 的应用表明，这些潜在的泡沫形成生物都具有丝状形态。此外，还表明氨和总氮的浓度与泡沫形成物的存在密切相关。本研究提供了关于嗜热 AD 系统中潜在泡沫形成微生物的身份的新见解，从而可以随后监测它们的丰度并研究它们的生态学。这些信息将重要地为这些有问题的微生物的控制措施的开发提供信息。
