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Abstract
Bacteria remodel their plasma membrane lipidome to maintain key biophysical attributes in response to ecological disturbances. ForHalanaerobiumand other anaerobic halotolerant taxa that persist in hydraulically fractured deep subsurface shale reservoirs, salinity, and hydraulic retention time (HRT) are important perturbants of cell membrane structure, yet their effects remain poorly understood. Membrane-linked activities underliein situmicrobial growth kinetics and physiologies which drive biogeochemical reactions in engineered subsurface systems. Hence, we used gas chromatography–mass spectrometry (GC–MS) to investigate the effects of salinity and HRT on the phospholipid fatty acid composition ofH. congolenseWG10 and mixed enrichment cultures from hydraulically fractured shale wells. We also coupled acyl chain remodeling to membrane mechanics by measuring bilayer elasticity using atomic force microscopy (AFM). For these experiments, cultures were grown in a chemostat vessel operated in continuous flow mode under strict anoxia and constant stirring. Our findings show that salinity and HRT induce significant changes in membrane fatty acid chemistry ofH. congolenseWG10 in distinct and complementary ways. Notably, under nonoptimal salt concentrations (7% and 20% NaCl),H. congolenseWG10 elevates the portion of polyunsaturated fatty acids (PUFAs) in its membrane, and this results in an apparent increase in fluidity (homeoviscous adaptation principle) and thickness. Double bond index (DBI) and mean chain length (MCL) were used as proxies for membrane fluidity and thickness, respectively. These results provide new insight into our understanding of how environmental and engineered factors might disrupt the physical and biogeochemical equilibria of fractured shale by inducing physiologically relevant changes in the membrane fatty acid chemistry of persistent microbial taxa.
GRAPHICAL ABSTRACT
Salinity significantly alters membrane bilayer fluidity and thickness inHalanaerobium congolenseWG10.
Department
Open Access Fund; Natural Resources and the Environment; Civil Engineering
Publication Date
11-10-2022
Journal Title
Frontiers in Microbiology
Publisher
Frontiers
Digital Object Identifier (DOI)
Document Type
Article
Recommended Citation
Ugwuodo, C. J., Colosimo, F., Adhikari, J., Shen, Y., Badireddy, A. R., & Mouser, P. J. (2022). Salinity and hydraulic retention time induce membrane phospholipid acyl chain remodeling in Halanaerobium congolense WG10 and mixed cultures from hydraulically fractured shale wells. Frontiers in Microbiology, 13. https://doi.org/10.3389/fmicb.2022.1023575
Rights
Copyright © 2022 Ugwuodo, Colosimo, Adhikari, Shen, Badireddy and Mouser. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice.
Comments
This is an Open Access article published by Frontiers in Frontiers in Microbiology, available online: https://dx.doi.org/10.3389/fmicb.2022.1023575