Efforts to integrate biogas plants into bioeconomy concepts will lead to an expansion of manure-based (small) biogas plants, while their operation is challenging due to critical characteristics of some types of livestock manure. For a better process understanding, in this study, three manure-based small biogas plants were investigated with emphasis on microbiome diversity. Due to varying digester types, feedstocks, and process conditions, 16S rRNA gene amplicon sequencing showed differences in the taxonomic composition. Dynamic variations of each investigated biogas plant microbiome over time were analyzed by terminal restriction fragment length polymorphism (TRFLP), whereby nonmetric multidimensional scaling (NMDS) revealed two well-running systems, one of them with a high share of chicken manure, and one unstable system. By using Threshold Indicator Taxa Analysis (TITAN), community-level change points at ammonium and ammonia concentrations of 2.25 g L^-1 and 193 mg L^-1 or volatile fatty acid concentrations of 0.75 g L^-1were reliably identified which are lower than the commonly reported thresholds for critical process stages based on chemical parameters. Although a change in the microbiome structure does not necessarily indicate an upcoming critical process stage, the recorded community-level change points might be a first indication to carefully observe the process.

中文翻译：

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基于粪便的小型沼气厂中的微生物组多样性和社区级变化点。

将沼气厂纳入生物经济概念的努力将导致以粪便为基础的（小型）沼气厂的发展，而由于某些类型的牲畜粪便的关键特性，其运行具有挑战性。为了更好地了解过程，在本研究中，对三个以粪便为基础的小型沼气厂进行了研究，重点是微生物组多样性。由于消化器类型，原料和加工条件的不同，16S rRNA基因扩增子测序显示出分类学组成上的差异。通过终端限制片段长度多态性（TRFLP）分析了每个调查的沼气厂微生物组随时间的动态变化，其中非度量多维标度（NMDS）显示了两个运行良好的系统，其中一个具有较高的鸡粪比例，一个不稳定系统。可以可靠地确定^-1和193 mg L ^-1或0.75 g L ^-1的挥发性脂肪酸浓度，这些浓度低于基于化学参数的关键工艺阶段的常用阈值。尽管微生物组结构的变化不一定表明即将到来的关键过程阶段，但记录的社区级变化点可能是仔细观察过程的第一个指示。