The ecology of aerobic microorganisms is never explored in marine oxygen minimum zone (OMZ) sediments. Here we reveal aerobic bacterial communities along ∼3 m sediment-horizons of the eastern Arabian Sea OMZ. Sulfide-containing sediment-cores retrieved from 530 mbsl (meters beneath the sea-level) and 580 mbsl were explored at 15–30 cm intervals, using metagenomics, pure-culture-isolation, genomics and metatranscriptomics. Genes for aerobic respiration, and oxidation of methane/ammonia/alcohols/thiosulfate/sulfite/organosulfur-compounds, were detected in the metagenomes from all 25 sediment-samples explored. Most probable numbers for aerobic chemolithoautotrophs and chemoorganoheterotrophs at individual sample-sites were up to 1.1 × 10⁷ (g sediment)^-1. The sediment-sample collected from 275 cmbsf (centimeters beneath the seafloor) of the 530-mbsl-core yielded many such obligately aerobic isolates belonging to Cereibacter, Guyparkeria, Halomonas, Methylophaga, Pseudomonas and Sulfitobacter which died upon anaerobic incubation, despite being provided with all possible electron acceptors and fermentative substrates. High percentages of metatranscriptomic reads from the 275 cmbsf sediment-sample, and metagenomic reads from all 25 sediment-samples, matched the isolates’ genomic sequences including those for aerobic metabolisms, genetic/environmental information processing and cell division, thereby illustrating the bacteria's in-situ activity, and ubiquity across the sediment-horizons, respectively. The findings hold critical implications for organic carbon sequestration/remineralization, and inorganic compounds oxidation, within the sediment realm of global marine OMZs.

中文翻译：

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海洋最低氧区沉积物中的好氧微生物群落

有氧微生物的生态学从未在海洋最低氧区域（OMZ）沉积物中进行过探索。在这里，我们揭示了阿拉伯海东部OMZ约3 m沉积物水平上的好氧细菌群落。使用宏基因组学，纯培养分离，基因组学和超转录组学技术，以15–30 cm的间隔探索了从530 mbsl（海平面以下的米）和580 mbsl回收的含硫化物的沉积物核。在所研究的所有25个沉积物样本的基因组中均检测到有氧呼吸和甲烷/氨气/乙醇/硫代硫酸盐/亚硫酸盐/有机硫化合物氧化的基因。单个样品位点上好氧化石自养生物和化学有机异养生物的最可能数为1.1×10 ⁷（g沉积物）^-1。从275 cmbsf（海底下方厘米）的530-mbsl核心产生了许多这样的专性需氧的分离物属于收集的沉积物样品Cereibacter，Guyparkeria，盐单胞菌，Methylophaga，假单胞菌和Sulfitobacter其死亡在厌氧培养，尽管设置有所有可能的电子受体和发酵底物。来自275 cmbsf沉积物样品的高转录组转录读数和来自所有25个沉积物样品的宏基因组读数均与分离株的基因组序列相匹配，包括有氧代谢，遗传/环境信息处理和细胞分裂的基因组序列，从而说明了细菌的原位活动和整个沉积物水平上的普遍存在。这些发现对于全球海洋OMZ沉积物领域内的有机碳固存/再矿化以及无机化合物的氧化具有至关重要的意义。