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Differential protein expression during growth on model and commercial mixtures of naphthenic acids in Pseudomonas fluorescens Pf-5
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  • Boyd McKew,
  • Richard Johnson,
  • Lindsey Clothier,
  • Karl Skeels,
  • Matthew Ross,
  • Metodi Metodiev,
  • Max Frenzel,
  • Lisa Gieg,
  • Jonathan Martin,
  • Michael Hough,
  • Corinne Whitby
Boyd McKew
University of Essex
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Richard Johnson
University of Essex
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Lindsey Clothier
Nautilus Environmental
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Karl Skeels
University of Essex
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Matthew Ross
MacEwan University
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Metodi Metodiev
University of Essex
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Max Frenzel
Oil Plus Ltd
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Lisa Gieg
University of Calgary
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Jonathan Martin
Stockholm University
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Michael Hough
University of Essex
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Corinne Whitby
University of Essex
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Abstract

Naphthenic acids (NAs) are carboxylic acids with the formula (CnH2n+ZO2) and are the toxic, persistent constituents of oil sands process-affected waters (OSPW), produced during oil sands extraction. Currently, the proteins and mechanisms involved in NA biodegradation are unknown. Using LC-MS/MS shotgun proteomics, we identified proteins overexpressed during the growth of Pseudomonas fluorescens Pf5 on a model NA (4-n-butylphenyl)-4-butanoic acid (n-BPBA) and commercial NA mixture (Acros). By day 11, >95% of n-BPBA was degraded. With Acros, a 17% reduction in intensity occurred with 10-18 carbon compounds of the Z family -2 to -14 (major NA species in this mixture). A total of 554 proteins (n-BPBA) and 631 proteins (Acros) were overexpressed during growth on NAs; including several transporters (e.g. ABC transporters), suggesting a cellular protective response from NA toxicity. Several proteins associated with fatty acid, lipid and amino acid metabolism were also overexpressed; including acyl-CoA dehydrogenase and acyl-CoA thioesterase II, which catalyze part of the fatty acid beta-oxidation pathway. Indeed, multiple enzymes involved in the fatty acid oxidation pathway were upregulated. Given the presumed structural similarity between alkyl-carboxylic acid side chains and fatty acids, we postulate that P. fluorescens Pf-5 was using existing fatty acid catabolic pathways (among others) during NA degradation.

Peer review status:IN REVISION

15 Mar 2021Submitted to MicrobiologyOpen
16 Mar 2021Assigned to Editor
16 Mar 2021Submission Checks Completed
17 Mar 2021Reviewer(s) Assigned
07 Apr 2021Review(s) Completed, Editorial Evaluation Pending
07 Apr 2021Editorial Decision: Revise Minor