Membrane fluidity and fatty acid comparisons in psychrotrophic and mesophilic strains of Acidithiobacillus ferrooxidans under cold growth temperatures |
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Authors: | Nadia C S Mykytczuk Jack T Trevors Susan M Twine Garry D Ferroni Leo G Leduc |
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Institution: | (1) Department of Biology, Laurentian University, Sudbury, ON, P3E 2C6, Canada;(2) School of Environmental Sciences, University of Guelph, Guelph, ON, N1G 2W1, Canada;(3) Institute for Biological Sciences, National Research Council of Canada, Ottawa, ON, K1A0R6, Canada;(4) Division of Medical Sciences, Northern Ontario School of Medicine, Laurentian Campus, Sudbury, ON, P3E 2C6, Canada |
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Abstract: | Psychrotrophic strains of Acidithiobacillus ferrooxidans have an important role in metal leaching and acid mine drainage (AMD) production in colder mining environments. We investigated
cytoplasmic membrane fluidity and fatty acid alterations in response to low temperatures (5 and 15°C). Significant differences
in membrane fluidity, measured by polarization (P) of 1,6-diphenyl-1,3,5-hexatriene (DPH), were found where the psychrotrophic
strains had a significantly more rigid membrane (P range = 0.41–0.45) and lower transition temperature midpoints (T
m = 2.0°C) and broader transition range than the mesophilic strains (P range = 0.38–0.39; T
m = 2.0–18°C) at cold temperatures. Membrane remodeling was evident in all strains with a common trend of increased unsaturated
fatty acid component in response to lower growth temperatures. In psychrotrophic strains, decreases in 12:0 fatty acids distinguished
the 5°C fatty acid profiles from those of the mesophilic strains that showed decreases in 16:0, 17:0, and cyclo-19:0 fatty
acids. These changes were also correlated with the observed changes in membrane fluidity (R
2 = 63–97%). Psychrotrophic strains employ distinctive modulation of cytoplasmic membrane fluidity with uncommon membrane phase
changes as part of their adaptation to the extreme AMD environment in colder climates. |
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