Comparative proteomics of a novel Pseudomonas veronii SBNG uncovers divergent degradation pathways for benzene and monochlorobenzene.

Abstract

Aromatic and chloroaromatic hydrocarbon pollution poses a significant threat to environmental and human health. In this study, we isolated a novel Pseudomonas veronii strain SBNG (99.7% purity) from groundwater contaminated with lindane and aromatics. Strain SBNG mineralizes benzene and monochlorobenzene (MCB), and is capable of cometabolizing toluene in the presence of MCB. Other compounds present in the contaminated groundwater (1,2-, 1,4-, and 1,3-dichlorobenzene, 1,2,4-, 1,2,3-, and 1,3,5-trichlorobenzene, BTEX and lindane) were not transformed by strain SBNG but did not inhibit MCB degradation at the concentrations tested in microcosms. Genomic sequencing combined with proteomic analysis via mass spectrometry during growth on benzene, MCB, or acetate suggested that benzene and MCB transformation proceeds via a toluene dioxygenase (TOD) pathway, followed by ortho-cleavage of catechol intermediates. To the best of our knowledge, this is the first study to characterize the whole-proteome of a Pseudomonas strain growing on a chloroaromatic as a carbon source. Comparative proteomics elucidated an initial degradation route catalyzed by benzene-1,2-dioxygenase and cis-1,2-dihydrobenzene-1,2-diol dehydrogenase, while divergent proteomic profiles were observed for downstream catabolic steps. Furthermore, distinct cellular adaptations and differential responses to benzene and MCB toxicity were identified. These results, complemented by comparative genomic analysis with other P. veronii strains, highlight the remarkable metabolic diversity and versatility of aromatic degradation pathways within this species, providing essential data for the design of effective bioremediation strategies.

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