Bertagnolli Anthony D, Padilla Cory C, Glass Jennifer B, Thamdrup Bo, Stewart Frank J
School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA.
School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA.
Environ Microbiol. 2017 Nov;19(11):4392-4416. doi: 10.1111/1462-2920.13879. Epub 2017 Nov 2.
Marinimicrobia bacteria are widespread in subeuphotic areas of the oceans and particularly abundant in oxygen minimum zones (OMZs). Information on Marinimicrobia metabolism is sparse, making the biogeochemical influence of this group challenging to predict. Here, metagenome-assembled genomes representing Marinimicrobia subgroups PN262000N21 and ARCTIC96B-7 were retrieved to near completion (97% and 94%) from OMZ metagenomes, with contamination (14.1%) observed only in ARCTIC96B-7. Genes for aerobic carbon monoxide (CO) oxidation, polysulfide metabolism and hydrogen utilization were identified only in PN262000N21, while genes for partial denitrification occurred in both genomes. Transcripts mapping to these genomes increased from <0.3% of total mRNA from the oxic zone to a max of 22% under anoxia. ARCTIC96B-7 transcript representation decreased an order of magnitude from non-sulfidic to sulfidic depths. In contrast, PN262000N21 representation was relatively constant throughout the OMZ, although transcripts encoding sulfur-utilizing proteins, including sulfur transferases, were enriched at sulfidic depths. PN262000N21 transcripts encoding a protein with fibronectin domains similar to those in cellulosome-producing bacteria were also abundant, suggesting a potential for high molecular weight carbon cycling. These data provide omic-level descriptions of metabolic potential and activity in OMZ-associated Marinimicrobia, suggesting differentiation between subgroups with roles in carbon and dissimilatory inorganic nitrogen and sulfur cycling.
海生微菌在海洋次真光层广泛分布，在氧含量极小带（OMZs）中尤为丰富。关于海生微菌代谢的信息匮乏，使得该菌群对生物地球化学的影响难以预测。在此，从OMZ宏基因组中检索到代表海生微菌亚群PN262000N21和ARCTIC96B - 7的宏基因组组装基因组，组装完成度接近（分别为97%和94%），仅在ARCTIC96B - 7中观察到污染（14.1%）。仅在PN262000N21中鉴定出有氧一氧化碳（CO）氧化、多硫化物代谢和氢气利用的基因，而部分反硝化作用的基因在两个基因组中均有出现。映射到这些基因组的转录本从含氧区总mRNA的<0.3%增加到缺氧条件下的最高22%。ARCTIC96B - 7的转录本丰度从非硫化深度到硫化深度下降了一个数量级。相比之下，PN262000N21的丰度在整个OMZ中相对恒定，尽管编码包括硫转移酶在内的硫利用蛋白的转录本在硫化深度处富集。编码与产纤维小体细菌中类似的具有纤连蛋白结构域蛋白质的PN262000N21转录本也很丰富，表明其在高分子量碳循环方面具有潜力。这些数据提供了与OMZ相关的海生微菌代谢潜力和活性的组学水平描述，表明亚群之间在碳以及异化无机氮和硫循环中的作用存在差异。
