Lackner Nina, Wagner Andreas O, Markt Rudolf, Illmer Paul
Department of Microbiology, Universität Innsbruck, 6020 Innsbruck, Austria.
Microorganisms. 2020 Feb 20;8(2):286. doi: 10.3390/microorganisms8020286.
pH is a central environmental factor influencing CH production from organic substrates, as every member of the complex microbial community has specific pH requirements. Here, we show how varying pH conditions (5.0-8.5, phosphate buffered) and the application of a phosphate buffer per se induce shifts in the microbial community composition and the carbon flow during nine weeks of thermophilic batch digestion. Beside monitoring the methane production as well as volatile fatty acid concentrations, amplicon sequencing of the 16S rRNA gene was conducted. The presence of 100 mM phosphate resulted in reduced CH production during the initial phase of the incubation, which was characterized by a shift in the dominant methanogenic genera from a mixed and to a pure system. In buffered samples, acetate strongly accumulated in the beginning of the batch digestion and subsequently served as a substrate for methanogens. Methanogenesis was permanently inhibited at pH values ≤5.5, with the maximum CH production occurring at pH 7.5. Adaptations of the microbial community to the pH variations included shifts in the archaeal and bacterial composition, as less competitive organisms with a broad pH range were able to occupy metabolic niches at unfavorable pH conditions.
pH是影响有机底物产甲烷的核心环境因素，因为复杂微生物群落的每个成员都有特定的pH要求。在此，我们展示了不同pH条件（5.0 - 8.5，磷酸盐缓冲）以及磷酸盐缓冲液本身的应用如何在嗜热批次消化的九周过程中诱导微生物群落组成和碳流的变化。除了监测甲烷产量和挥发性脂肪酸浓度外，还进行了16S rRNA基因的扩增子测序。100 mM磷酸盐的存在导致孵化初期甲烷产量降低，其特征是主要产甲烷菌属从混合的变为纯的系统。在缓冲样品中，乙酸盐在批次消化开始时强烈积累，随后作为产甲烷菌的底物。在pH值≤5.5时甲烷生成被永久抑制，最大甲烷产量出现在pH 7.5时。微生物群落对pH变化的适应包括古菌和细菌组成的变化，因为具有较宽pH范围的竞争力较弱的生物体能够在不利的pH条件下占据代谢生态位。
