McKew, Boyd A.Johnson, RichardClothier, LindsaySkeels, KarlRoss, Matthew S.Metodiev, MetodiFrenzel, MaxGieg, Lisa M.Martin, Jonathan W.Hough, Michael A.Whitby, Corinne2022-01-182022-05-312022-05-312021McKew, B.A., Johnson, R., Clothier, L., Skeels, K., Ross, M.S., Metodiev, M., Frenzel, M., Gieg, L.M., Martin, J.W., Hough, M.A. and Whitby, C. (2021), Differential protein expression during growth on model and commercial mixtures of naphthenic acids in Pseudomonas fluorescens Pf-5. MicrobiologyOpen, 10, article e1196. https://doi.org/10.1002/mbo3.1196https://hdl.handle.net/20.500.14078/2551Naphthenic acids (NAs) are carboxylic acids with the formula (CnH2n+ZO2) and are among the most 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 Pf-5 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.2.18MBPDFenAttribution (CC BY)naphthenic acidsoil sands process-affected waterproteomicsPseudomonas fluorescenstailing pondstoxicityArticlehttps://doi.org/10.1002/mbo3.1196