Bacterially driven anaerobic sulfide oxidation by manganese oxide reduction studied in Sulfurimonas spp. (ANAMARE)

通过氧化锰还原的厌氧硫化物氧化的氧化还原反应已被反复建议作为细菌的可能能量来源，但所有早期尝试富集具有这种特定代谢的微生物都失败了。在这个项目中，我们建议研究一个新分离的细菌菌株，这是增长的石自养硫化物或硫代硫酸盐作为电子供体和氧化锰（IV）作为唯一的电子受体。该分离物来源于黑海中部的亚氧区，属于硫单胞菌属。已知该属在海洋氧化还原酶中丰富，但早期获得的所有菌株都将厌氧硫化物氧化与反硝化偶联。第一次实验表明，由新菌株进行的硫化物和氧化锰之间的细菌介导的反应比化学反应快至少3-5倍。在该项目的过程中，我们计划深入表征新菌株的生长，例如在生长速率、生长效率和中间体如Mn（III）和S 0在培养基中的积累方面。此外，我们希望获得所有的信息，这是必要的，以了解这个物种的个体生态学和定义它的生态位。这将包括研究替代电子供体和受体的使用、有机碳源的使用、固氮、运动性和pH值、盐度和温度方面的最佳生长条件。利用这些信息，我们的目标是有效地描述新菌株并将其存款在德国培养物保藏中心。最后，我们计划对该菌株的基因组进行测序，并与其他3种硫单胞菌进行比较基因组和生理学研究，其纯培养物和完整的基因组序列均可获得。因此，我们可以对这种新的厌氧硫化物氧化在硫单胞菌属内的传播范围有多广有初步的印象，最重要的是，我们可以寻找参与这种代谢的指示基因。结合实验工作，基因组分析将集中在不溶性锰氧化物可用作电子受体的模式。

The redox reaction of anaerobic sulfide oxidation by manganese oxide reduction has been repeatedly suggested as a possible energy source for bacteria, but all earlier attempts to enrich for microorganisms with this particular metabolism failed. In this project we propose to study a newly isolated bacterial strain, which is growing lithoautotrophically with sulfide or thiosulfate as electron donor and manganese(IV) oxide as sole electron acceptor. The isolate originates from the suboxic zone of the central Black Sea and belongs to the genus Sulfurimonas. This genus is known to be abundant in marine redoxclines, but all strains obtained earlier couple anaerobic sulfide oxidation with denitrification. First experiments revealed, that the bacterial mediated reaction between sulfide and manganese oxide, carried out by the new strain, is at least 3-5 times faster than the chemical reaction. In the course of this project, we plan to characterize the growth of the new strain in depth e.g. in terms of growth rate, growth efficiency and accumulation of intermediates such as Mn(III) and S0 in the medium. Further on, we want to gain all information, which is necessary to understand the autecology of this species and define it's ecological niche. This will include e.g. studies addressing the use of alternative electron donors and acceptors, the use of organic carbon sources, nitrogen fixation, motility and optimal growth conditions in terms of pH, salinity and temperature. With this information we aim to validly describe the new strain and deposit it in the German culture collection. Last not least we plan to sequence the genome of the strain and conduct a comparative genomic and physiological study with 3 other Sulfurimonas spp., for which both a pure culture and the complete genome sequences are available. Thereby, we can get a first impression on how wide spread this new anaerobic sulfide oxidation might be within the genus Sulfurimonas and most importantly we can search for indicative genes involved in this metabolism. In combination with experimental work, the genomic analysis will focus on the mode by which insoluble manganese oxide can be used as electron acceptor.