Winogradsky Institute of Microbiology, Federal Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, Russia.
Department of Biotechnology, Delft University of Technology, Delft, The Netherlands.
Extremophiles. 2021 Mar;25(2):173-180. doi: 10.1007/s00792-021-01219-y. Epub 2021 Feb 23.
Dimethylsulfoxide (DMSO) has long been known to support anaerobic respiration in a few species of basically aerobic extremely halophilic euryarchaea living in hypersaline lakes. Recently, it has also been shown to be utilized as an additional electron acceptor in basically anaerobic sulfur-reducing haloarchaea. Here we investigated whether haloarchaea would be capable of anaerobic respiration with other two sulfoxides, methionine sulfoxide (MSO) and tetramethylene sulfoxide (TMSO). For this, anaerobic enrichment cultures were inoculated with sediments from hypersaline salt and soda lakes in southwestern Siberia and southern Russia. Positive enrichments were obtained for both MSO and TMSO with yeast extract but not with formate or acetate as the electron donor. Two pure cultures obtained from salt lakes, either with MSO or TMSO, were obligate anaerobes closely related to sulfur-reducing Halanaeroarchaeum sulfurireducens, although the type strain of this genus was unable to utilize any sulfoxides. Two pure cultures isolated from soda lakes were facultatively anaerobic alkaliphilic haloarchaea using O, sulfur and sulfoxides as the electron acceptors. One isolate was identical to the previously described sulfur-reducing Natrarchaeobaculum sulfurireducens, while another one, enriched at lower alkalinity, is forming a new species in the genus Halobiforma. Since all isolates enriched with either MSO or TMSO were able to respire all three sulfoxides including DMSO and the corresponding activities were cross-induced, it suggest that a single enzyme of the DMSO-reductase family with a broad substrate specificity is responsible for various sulfoxide-dependent respiration in haloarchaea.
二甲基亚砜（DMSO）长期以来一直被认为能够支持少数基本好氧的极端嗜盐广古菌在高盐湖泊中进行无氧呼吸。最近，它也被证明可作为基本无氧的硫还原古菌的另一种电子受体。在这里，我们研究了其他两种亚砜，蛋氨酸亚砜（MSO）和四亚甲基亚砜（TMSO）是否能被 haloarchaea 进行无氧呼吸。为此，我们用来自西伯利亚西南部和俄罗斯南部高盐盐湖的沉积物接种了厌氧富集培养物。MSO 和 TMSO 都可以用酵母提取物进行阳性富集，但不能用甲酸盐或乙酸盐作为电子供体。从盐湖获得的两种纯培养物，无论是用 MSO 还是 TMSO，都是严格厌氧菌，与硫还原 Halanaeroarchaeum sulfurireducens密切相关，尽管该属的模式菌株不能利用任何亚砜。从苏打湖分离出的两种纯培养物是兼性厌氧的嗜碱性 haloarchaea，可用 O、硫和亚砜作为电子受体。一个分离株与先前描述的硫还原 Natrarchaeobaculum sulfurireducens 相同，而另一个在较低碱度下富集的分离株形成了 Halobiforma 属中的一个新种。由于用 MSO 或 TMSO 富集的所有分离株都能够呼吸三种亚砜，包括 DMSO，并且相应的活性是交叉诱导的，这表明具有广泛底物特异性的 DMSO 还原酶家族的单一酶负责 haloarchaea 中各种依赖亚砜的呼吸。
