背景:最近的研究报道了深层(>1000m)硫化物海洋栖息地中涉及有机物(OM)降解的关键厌氧菌的身份和功能。然而,由于缺乏可用的分离株,对其生理学的详细调查已被排除。在这项研究中,我们培养并表征了黑海深层(2000m深度)硫化水中可能参与OM降解的各种新型厌氧菌的生态生理学。
结果:我们已经成功地培育了一组属于不同门的新型厌氧菌,包括镰刀菌(菌株S5),芽孢杆菌(菌株A1T和A2),螺旋藻(菌株M1T,M2和S2),拟杆菌(菌株B1T,B2,S6,L6,SYP,和M2P),Cloacimonadota(Cloa-SY6),Planctomycetota(Plnct-SY6),支原体(Izemo-BS),Chloroflexota(Chflx-SY6),和脱硫杆菌(菌株S3T和S3-i)。这些微生物能够在高达50MPa的高静水压力下生长。此外,这项研究表明,不同的厌氧菌专门降解特定类型的OM。与门梭菌相关的菌株,芽孢杆菌,Planctomycetota,支原体被发现专门降解纤维素,纤维二糖,甲壳素,和DNA,分别,虽然与螺旋藻属有联系的菌株,拟杆菌,泄殖腔,和Chloroflexota更喜欢发酵不太复杂的OM形式。我们还确定了脱硫杆菌门的成员是终末氧化剂,可能参与发酵过程中产生的氢的消耗。这些结果得到了培养的微生物类群的(元)基因组中编码特定代谢途径蛋白质的基因鉴定的支持。此外,我们分析了选定分类群的膜脂组成,这对于它们在深层硫化水域的恶劣环境中的生存至关重要,并且可能被用作黑海硫化水域中这些菌株的生物特征。
结论:这是第一份报告,证明了来自任何硫化物海洋栖息地的如此多样化的微生物群的培养和生态生理学。总的来说,这项研究为我们对在黑海深层硫化水域的极端条件下蓬勃发展的微生物的理解迈出了一步。视频摘要。
BACKGROUND: Recent studies have reported the identity and functions of key anaerobes involved in the degradation of organic matter (OM) in deep (> 1000 m) sulfidic marine habitats. However, due to the lack of available isolates, detailed investigation of their physiology has been precluded. In this study, we cultivated and characterized the ecophysiology of a wide range of novel anaerobes potentially involved in OM degradation in deep (2000 m depth) sulfidic waters of the Black Sea.
RESULTS: We have successfully cultivated a diverse group of novel anaerobes belonging to various phyla, including Fusobacteriota (strain S5), Bacillota (strains A1T and A2), Spirochaetota (strains M1T, M2, and S2), Bacteroidota (strains B1T, B2, S6, L6, SYP, and M2P), Cloacimonadota (Cloa-SY6), Planctomycetota (Plnct-SY6), Mycoplasmatota (Izemo-BS), Chloroflexota (Chflx-SY6), and Desulfobacterota (strains S3T and S3-i). These microorganisms were able to grow at an elevated hydrostatic pressure of up to 50 MPa. Moreover, this study revealed that different anaerobes were specialized in degrading specific types of OM. Strains affiliated with the phyla Fusobacteriota, Bacillota, Planctomycetota, and Mycoplasmatota were found to be specialized in the degradation of cellulose, cellobiose, chitin, and DNA, respectively, while strains affiliated with Spirochaetota, Bacteroidota, Cloacimonadota, and Chloroflexota preferred to ferment less complex forms of OM. We also identified members of the phylum Desulfobacterota as terminal oxidizers, potentially involved in the consumption of hydrogen produced during fermentation. These results were supported by the identification of genes in the (meta)genomes of the cultivated microbial taxa which encode proteins of specific metabolic pathways. Additionally, we analyzed the composition of membrane lipids of selected taxa, which could be critical for their survival in the harsh environment of the deep sulfidic waters and could potentially be used as biosignatures for these strains in the sulfidic waters of the Black Sea.
CONCLUSIONS: This is the first report that demonstrates the cultivation and ecophysiology of such a diverse group of microorganisms from any sulfidic marine habitat. Collectively, this study provides a step forward in our understanding of the microbes thriving in the extreme conditions of the deep sulfidic waters of the Black Sea. Video Abstract.