In the dark ocean, the SAR324 group of Delta-proteobacteria has been associated with a chemolithotrophic lifestyle. However, their electron transport chain for energy generation and information system has not yet been well characterized. In the present study, four SAR324 draft genomes were extracted from metagenomes sampled from hydrothermal plumes in the South Mid-Atlantic Ridge. We describe novel electron transport chain components in the SAR324 group, particularly the alternative complex III, which is involved in energy generation. Moreover, we propose that the C-type cytochrome, for example the C553, may play a novel role in electron transfer, adding to our knowledge regarding the energy generation process in the SAR324 cluster. The central carbon metabolism in the described SAR324 genomes exhibits several new features other than methanotrophy e.g. aromatic compound degradation. This suggests that methane oxidation may not be the main central carbon metabolism component in SAR324 cluster bacteria. The reductive acetyl-CoA pathway may potentially be essential in carbon fixation due to the absence of components from the Calvin-Benson cycle. Our study provides insight into the role of recombination events in shaping the genome of the SAR324 group based on a larger number of repeat regions observed, which has been overlooked thus far.
|Original language||English (US)|
|State||Published - Mar 8 2016|
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This study was supported by grants from the National Basic Research Program of China (973 Program, No: 2012CB417304) and the China Ocean Mineral Resources R & D Association (COMRRDA/12.SC02) (DY125-15-R-01) to Pei-Yuan Qian, and the State Key Laboratory of Marine Geology, Tongji University (MGK1401) to Huiluo Cao. We thank the R/V “Da-Yang Yi-Hao” crews for their assistance with the sample collections. Salim Bougouffa was supported by a SABIC Postdoctoral Fellowship. Vladimir Bajic was supported by a KAUST Base Research Fund.