气候变化领域集成服务门户(CCPortal): Vitamin B12-dependent biosynthesis ties amplified 2-methylhopanoid production during oceanic anoxic events to nitrification

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DOI	10.1073/PNAS.2012357117
	Vitamin B12-dependent biosynthesis ties amplified 2-methylhopanoid production during oceanic anoxic events to nitrification
	Elling F.J.; Hemingway J.D.; Evans T.W.; Kharbush J.J.; Spieck E.; Summons R.E.; Pearson A.
发表日期	2021
ISSN	00278424
起始页码	32996
结束页码	33004
卷号	117 期号:52
英文摘要	Bacterial hopanoid lipids are ubiquitous in the geologic record and serve as biomarkers for reconstructing Earth’s climatic and biogeochemical evolution. Specifically, the abundance of 2-methylhopanoids deposited during Mesozoic ocean anoxic events (OAEs) and other intervals has been interpreted to reflect proliferation of nitrogen-fixing marine cyanobacteria. However, there currently is no conclusive evidence for 2-methylhopanoid production by extant marine cyanobacteria. As an alternative explanation, here we report 2-methylhopanoid production by bacteria of the genus Nitrobacter, cosmopolitan nitrite oxidizers that inhabit nutrient-rich freshwater, brackish, and marine environments. The model organism Nitrobacter vulgaris produced only trace amounts of 2-methylhopanoids when grown in minimal medium or with added methionine, the presumed biosynthetic methyl donor. Supplementation of cultures with cobalamin (vitamin B12) increased nitrite oxidation rates and stimulated a 33-fold increase of 2-methylhopanoid abundance, indicating that the biosynthetic reaction mechanism is cobalamin dependent. Because Nitrobacter spp. cannot synthesize cobalamin, we postulate that they acquire it from organisms inhabiting a shared ecological niche—for example, ammonia-oxidizing archaea. We propose that during nutrient-rich conditions, cobalamin-based mutualism intensifies upper water column nitrification, thus promoting 2-methylhopanoid deposition. In contrast, anoxia underlying oligotrophic surface ocean conditions in restricted basins would prompt shoaling of anaerobic ammonium oxidation, leading to low observed 2-methylhopanoid abundances. The first scenario is consistent with hypotheses of enhanced nutrient loading during OAEs, while the second is consistent with the sedimentary record of Pliocene–Pleistocene Mediterranean sapropel events. We thus hypothesize that nitrogen cycling in the Pliocene–Pleistocene Mediterranean resembled modern, highly stratified basins, whereas no modern analog exists for OAEs. © 2020 National Academy of Sciences. All rights reserved.
英文关键词	Biomarker; Cobalamin; Hopanoids; Nitrification; Oceanic anoxic event
语种	英语
scopus关键词	2 methylhopanoid; cyanocobalamin; hopanoid; nitrite; unclassified drug; ammonia; cyanocobalamin; methionine; oxygen; pentacyclic triterpene; sea water; ammonia oxidizing archaeon; anaerobic ammonium oxidation; Article; controlled study; Mesozoic; nitrification; Nitrobacter; Nitrobacter vulgaris; nitrogen cycling; nonhuman; ocean acidification; oxidation; Pleistocene; Pliocene; priority journal; reaction analysis; sapropel; sea surface waters; vitamin metabolism; vitamin supplementation; chemistry; metabolism; plankton; Ammonia; Methionine; Nitrification; Nitrobacter; Oxygen; Pentacyclic Triterpenes; Plankton; Seawater; Vitamin B 12
来源期刊	Proceedings of the National Academy of Sciences of the United States of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/179633
作者单位	Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138, United States; Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, United States; Department of Earth and Environmental Science, University of Michigan, Ann Arbor, MI 48109, United States; Department of Microbiology and Biotechnology, University of Hamburg, Hamburg, 22609, Germany
推荐引用方式 GB/T 7714	Elling F.J.,Hemingway J.D.,Evans T.W.,et al. Vitamin B12-dependent biosynthesis ties amplified 2-methylhopanoid production during oceanic anoxic events to nitrification[J],2021,117(52).
APA	Elling F.J..,Hemingway J.D..,Evans T.W..,Kharbush J.J..,Spieck E..,...&Pearson A..(2021).Vitamin B12-dependent biosynthesis ties amplified 2-methylhopanoid production during oceanic anoxic events to nitrification.Proceedings of the National Academy of Sciences of the United States of America,117(52).
MLA	Elling F.J.,et al."Vitamin B12-dependent biosynthesis ties amplified 2-methylhopanoid production during oceanic anoxic events to nitrification".Proceedings of the National Academy of Sciences of the United States of America 117.52(2021).