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Effects of legacy metabolites from previous ecosystems on the environmental metabolomics of the brine of Lake Vida, East Antarctica

journal contribution
posted on 23.10.2018, 00:00 authored by Luoth Chou, Fabien Kenig, Alison E. Murray, Christian H. Fritsen, Peter T. Doran
Lake Vida, located in a closed basin in the McMurdo Dry Valleys, East Antarctica, permanently encapsulates an interstitial anoxic, aphotic, cold (−13 °C), brine ecosystem within 27+ m of ice. Metabolically active, but cold-limited, slow-growing bacteria were detected in the brine. Lake Vida brine is derived from the evaporation of a body of water that occupied the same basin prior to ∼2800 years ago. The characteristics of this body of water changed over time and, at one point, likely resembled other modern well-studied perennial ice-covered lakes of the Dry Valleys. We characterized the dichloromethane-extractable fraction of the environmental metabolome of Lake Vida brine in order to constrain current and ancient biogeochemical processes. Analysis of the dichloromethane-extract of Lake Vida brine by gas chromatography-mass spectrometry and comprehensive multidimensional gas chromatography-time of flight-mass spectrometry reveals the presence of legacy compounds (i.e. diagenetic products of chlorophylls and carotenoids) deriving from photosynthetic algae and anaerobic, anoxygenic photosynthetic bacteria. This legacy component dilutes the environmental signal of metabolites deriving from the extant bacterial community. The persistence of legacy metabolites (paleometabolites), apparent in Lake Vida brine, is a result of the slow turnover rates of the extant bacterial population due to low metabolic activities caused by the cold limitation. Such paleometabolites may also be preserved in other cold-limited or nutrient-depleted slow-growing ecosystems. When analyzing ecosystems with low metabolic rates, the presence of legacy metabolites must first be addressed in order to confidently recognize and interpret the environmental metabolome of the extant ecosystem.

Funding

L.C. was supported by the Chancellor’s Graduate Research Fellowship (University of Illinois at Chicago) and the Illinois Space Grant Consortium Graduate Research Fellowship. This work was supported in part by National Aeronautics and Space Administration (NASA)-ASTEP NAG5-12889 (to P.T.D. as PI; A.E.M., F.K., and C.H.F. as Co-PIs) and National Science Foundation (NSF) awards ANT-0739681 (to A.E.M. and C.H.F.) and ANT-0739698 (to P.T.D. and F.K.). In 2005, the NSF Office of Polar Programs provided logistical support through a cooperative agreement with NASA. The

History

Citation

Chou, L., Kenig, F., Murray, A. E., Fritsen, C. H., & Doran, P. T. (2018). Effects of legacy metabolites from previous ecosystems on the environmental metabolomics of the brine of Lake Vida, East Antarctica. Organic Geochemistry, 122, 161-170. doi:10.1016/j.orggeochem.2018.05.002

Publisher

Elsevier

Language

en_US

issn

0146-6380

Issue date

01/08/2018

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