Environmental Science Graduate Program, The Ohio State University, Columbus, OH 43210, USA.
Microb Ecol. 2013 Aug;66(2):351-62. doi: 10.1007/s00248-013-0234-z. Epub 2013 May 3.
Anaerobic digestion (AD) is an attractive microbiological technology for both waste treatment and energy production. Syntrophic acetogenic bacteria are an important guild because they are essential for maintaining efficient and stable AD operation. However, this guild is poorly understood due to difficulties to culture them. In this study, we developed specific PCR assays targeting the propionate-CoA transferase genes (pct) to investigate their diversity and distribution in several mesophilic anaerobic digesters and a bench-scale temperature-phased AD (TPAD) system. Phylogenetic analysis of sequenced pct amplicons revealed the occurrence of Syntrophobacter fumaroxidans and six other clusters of putative pct genes. Principal coordinate analysis (PCoA) showed that pct diversity and abundance were largely correlated to the feedstocks of the digesters, while little difference was seen between the granular and the liquid fractions of each digester or between the two digesters of the TPAD system. Cluster-specific qPCR analysis revealed major impact of feedstocks and fractions on the abundance of pct genes. Readily fermentable substrates such as sugar- or starch-rich feedstocks selected for pct genes (Cluster I) related to Syntrophobacter, while manure feedstock selected for pct clusters related to pct of Clostridium spp. These results suggest that propionate metabolism can be affected by feedstocks and partition differently between solid and liquid phases in digesters. The PCR assays developed in this study may serve as a tool to investigate propionate-oxidizing bacteria in anaerobic digesters and other anaerobic environments.
厌氧消化（AD）是一种有吸引力的微生物技术，既可以用于废物处理，也可以用于能源生产。协同产乙酸菌是一个重要的菌群，因为它们对于维持高效稳定的 AD 运行是必不可少的。然而，由于培养这些菌群存在困难，因此人们对这个菌群的了解甚少。在本研究中，我们开发了针对丙酸盐 -CoA 转移酶基因（pct）的特异性 PCR 检测方法，以研究它们在几个中温厌氧消化器和一个台式温度分相 AD（TPAD）系统中的多样性和分布。测序的 pct 扩增子的系统发育分析揭示了 S. fumaroxidans 和其他六个推定的 pct 基因簇的存在。主坐标分析（PCoA）表明，pct 的多样性和丰度与消化器的进料密切相关，而每个消化器的颗粒相和液相之间或 TPAD 系统的两个消化器之间几乎没有差异。特定于聚类的 qPCR 分析表明，进料和分数对 pct 基因的丰度有重大影响。易发酵的底物，如富含糖或淀粉的进料，选择与 Syntrophobacter 相关的 pct 基因（Cluster I），而粪肥进料则选择与 Clostridium spp. 的 pct 相关的 pct 聚类。这些结果表明，丙酸代谢可以受到进料的影响，并且在消化器中固体相与液相之间有不同的分配。本研究中开发的 PCR 检测方法可以作为研究厌氧消化器和其他厌氧环境中丙酸氧化细菌的工具。
