The metal(loid) and in particular the Arsenic (As) burden of thirteen agricultural biogas plants and two sewage sludge digesters were investigated together with the corresponding microbial consortia. The latter were characterized by ARISA (automated ribosomal intergenetic spacer analysis) and next generation sequencing. The consortia were found to cluster according to digester type rather than substrate or metal(loid) composition. For selected plants, individual As species in the liquid and gaseous phases were quantified, showing that the microorganisms actively metabolize and thereby remove the As from their environment via the formation of (methylated) volatile species. The As metabolites showed some dependency on the microbial consortia, while there was no statistical correlation with the substrate mix. Finally, slurry from one agricultural biogas plant and one sewage sludge digester was transferred into laboratory scale reactors (“satellite reactors”) and the response to a defined addition of As (30 and 60 µM sodium arsenite) was studied. The results corroborate the hypothesis of a rapid conversion of dissolved As species into volatile ones. Methanogenesis was reduced during that time, while there was no discernable toxic effect on the microbial population. However, the utilization of the produced biogas as replacement for natural gas, e.g. as fuel, may be problematic, as catalysts and machinery are known to suffer from prolonged exposure even to low As concentrations.

中文翻译：

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技术性沼气厂中的砷代谢：对居民菌群和下游单位的可能后果。

研究了十三家农业沼气厂和两个污水污泥消化池的金属（尤其是砷）负荷以及相应的微生物联盟。后者的特征在于ARISA（自动核糖体基因间间隔子分析）和下一代测序。发现该财团根据消化器类型而不是底物或金属（金属）组成成簇。对于选定的植物，对液相和气相中的各个As物种进行了定量分析，表明微生物通过（甲基化）挥发性物种的形成主动代谢并由此从环境中去除了As。砷代谢产物显示出对微生物聚生体的某种依赖性，而与底物混合物没有统计学相关性。最后，将来自一家农业沼气厂和一个污水污泥消化器的废水转移到实验室规模的反应器（“卫星反应器”）中，并研究了对确定添加的砷（30和60 µM亚砷酸钠）的响应。结果证实了将溶解的砷物质快速转化为挥发性物质的假设。在此期间，甲烷生成减少，而对微生物种群没有明显的毒性作用。然而，利用产生的沼气代替天然气，例如作为燃料可能是有问题的，因为已知催化剂和机械即使在低As浓度下也要长时间暴露。