Wintsche Babett, Glaser Karin, Sträuber Heike, Centler Florian, Liebetrau Jan, Harms Hauke, Kleinsteuber Sabine
Department of Environmental Microbiology, Helmholtz Centre for Environmental Research - UFZ Leipzig, Germany.
Department of Applied Ecology and Phycology, University of Rostock Rostock, Germany.
Front Microbiol. 2016 Dec 16;7:2034. doi: 10.3389/fmicb.2016.02034. eCollection 2016.
Trace elements (TE) play an essential role in all organisms due to their functions in enzyme complexes. In anaerobic digesters, control, and supplementation of TEs lead to stable and more efficient methane production processes while TE deficits cause process imbalances. However, the underlying metabolic mechanisms and the adaptation of the affected microbial communities to such deficits are not yet fully understood. Here, we investigated the microbial community dynamics and resulting process changes induced by TE deprivation. Two identical lab-scale continuous stirred tank reactors fed with distiller's grains and supplemented with TEs (cobalt, molybdenum, nickel, tungsten) and a commercial iron additive were operated in parallel. After 72 weeks of identical operation, the feeding regime of one reactor was changed by omitting TE supplements and reducing the amount of iron additive. Both reactors were operated for further 21 weeks. Various process parameters (biogas production and composition, total solids and volatile solids, TE concentration, volatile fatty acids, total ammonium nitrogen, total organic acids/alkalinity ratio, and pH) and the composition and activity of the microbial communities were monitored over the total experimental time. While the methane yield remained stable, the concentrations of hydrogen sulfide, total ammonia nitrogen, and acetate increased in the TE-depleted reactor compared to the well-supplied control reactor. and dominated the methanogenic communities in both reactors. However, the activity ratio of these two genera was shown to depend on TE supplementation explainable by different TE requirements of their energy conservation systems. dominated the well-supplied anaerobic digester, pointing to acetoclastic methanogenesis as the dominant methanogenic pathway. Under TE deprivation, and thus hydrogenotrophic methanogenesis was favored although was not overgrown by . Multivariate statistics revealed that the decline of nickel, cobalt, molybdenum, tungsten, and manganese most strongly influenced the balance of transcripts from both genera. Hydrogenotrophic methanogens seem to be favored under nickel- and cobalt-deficient conditions as their metabolism requires less nickel-dependent enzymes and corrinoid cofactors than the acetoclastic and methylotrophic pathways. Thus, TE supply is critical to sustain the activity of the versatile high-performance methanogen .
微量元素（TE）因其在酶复合物中的功能，在所有生物体中都起着至关重要的作用。在厌氧消化器中，控制和补充微量元素可使甲烷生产过程稳定且更高效，而微量元素缺乏则会导致过程失衡。然而，其潜在的代谢机制以及受影响的微生物群落对这种缺乏的适应性尚未完全了解。在此，我们研究了微量元素剥夺引起的微生物群落动态及由此导致的过程变化。两个相同的实验室规模连续搅拌槽反应器，以酒糟为原料，并添加了微量元素（钴、钼、镍、钨）和一种商业铁添加剂，并行运行。在相同运行72周后，通过省略微量元素补充剂并减少铁添加剂的量，改变了其中一个反应器的进料方式。两个反应器都进一步运行了21周。在整个实验期间，监测了各种过程参数（沼气产量和组成、总固体和挥发性固体、微量元素浓度、挥发性脂肪酸、总铵氮、总有机酸/碱度比和pH值）以及微生物群落的组成和活性。与供应充足的对照反应器相比，在缺乏微量元素的反应器中，虽然甲烷产量保持稳定，但硫化氢、总氨氮和乙酸盐的浓度增加。在两个反应器中， 和 主导了产甲烷群落。然而，这两个属的活性比显示取决于微量元素的补充情况，这可以通过它们能量守恒系统对不同微量元素的需求来解释。 在供应充足的厌氧消化器中占主导地位，表明乙酸裂解产甲烷是主要的产甲烷途径。在缺乏微量元素的情况下， 以及氢营养型产甲烷作用受到青睐，尽管 并没有因 而过度生长。多变量统计显示，镍、钴、钼、钨和锰的下降对这两个属的 转录本平衡影响最为强烈。氢营养型产甲烷菌似乎在镍和钴缺乏的条件下受到青睐，因为与乙酸裂解和甲基营养型途径相比，它们的代谢所需的镍依赖性酶和类咕啉辅因子更少。因此，微量元素供应对于维持多功能高性能产甲烷菌 的活性至关重要。
