Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Aalborg, Denmark.
ISME J. 2013 Jun;7(6):1161-72. doi: 10.1038/ismej.2013.6. Epub 2013 Feb 28.
'Candidatus Microthrix parvicella' is a lipid-accumulating, filamentous bacterium so far found only in activated sludge wastewater treatment plants, where it is a common causative agent of sludge separation problems. Despite attracting considerable interest, its detailed physiology is still unclear. In this study, the genome of the RN1 strain was sequenced and annotated, which facilitated the construction of a theoretical metabolic model based on available in situ and axenic experimental data. This model proposes that under anaerobic conditions, this organism accumulates preferentially long-chain fatty acids as triacylglycerols. Utilisation of trehalose and/or polyphosphate stores or partial oxidation of long-chain fatty acids may supply the energy required for anaerobic lipid uptake and storage. Comparing the genome sequence of this isolate with metagenomes from two full-scale wastewater treatment plants with enhanced biological phosphorus removal reveals high similarity, with few metabolic differences between the axenic and the dominant community 'Ca. M. parvicella' strains. Hence, the metabolic model presented in this paper could be considered generally applicable to strains in full-scale treatment systems. The genomic information obtained here will provide the basis for future research into in situ gene expression and regulation. Such information will give substantial insight into the ecophysiology of this unusual and biotechnologically important filamentous bacterium.
'微小微丝菌（Ca. Microthrix parvicella）'是一种积累脂质的丝状细菌，迄今为止只在活性污泥污水处理厂中发现，是污泥分离问题的常见病原体。尽管它引起了相当大的兴趣，但它的详细生理学仍然不清楚。在这项研究中，对 RN1 菌株的基因组进行了测序和注释，这有助于根据现有的原位和无菌实验数据构建理论代谢模型。该模型提出，在厌氧条件下，该生物优先积累长链脂肪酸作为三酰基甘油。利用海藻糖和/或多磷酸盐储存或长链脂肪酸的部分氧化可能为厌氧脂质摄取和储存提供所需的能量。将该分离株的基因组序列与具有增强生物除磷功能的两个全规模污水处理厂的宏基因组进行比较，发现高度相似，无菌和优势群落 'Ca. M. parvicella' 菌株之间的代谢差异很小。因此，本文提出的代谢模型可以被认为通常适用于全规模处理系统中的菌株。这里获得的基因组信息将为原位基因表达和调控的未来研究提供基础。这些信息将深入了解这种不寻常且具有生物技术重要性的丝状细菌的生态生理学。
