Proteomic analysis to unravel the biochemical mechanisms triggered by Bacillus toyonensis SFC 500-1E under chromium(VI) and phenol stress

Abstract

Bacillus toyonensis SFC 500-1E is amember of the consortium SFC 500-1 able to removeCr(VI) and simultaneously tolerate high phenol concentrations. In order to elucidate mechanisms utilized by this strain during the bioremediation process, the diferential expression pattern of proteinswas analyzed when it grew with or without Cr(VI)(10 mg/L) and Cr(VI)+phenol (10 and 300 mg/L),through two complementary proteomic approaches:gel-based (Gel-LC) and gel-free (shotgun) nanoUHPLC-ESI–MS/MS. A total of 400 diferentiallyexpressed proteins were identifed, out of which 152proteins were down-regulated under Cr(VI) and 205up-regulated in the presence of Cr(VI)+phenol, suggesting the extra efort made by the strain to adaptitself and keep growing when phenol was also added.The major metabolic pathways afected include carbohydrate and energetic metabolism, followed bylipid and amino acid metabolism. Particularly interesting were also ABC transporters and the ironsiderophore transporter as well as transcriptional regulators that can bind metals. Stress-associated globalresponse involving the expression of thioredoxins,SOS response, and chaperones appears to be crucialfor the survival of this strain under treatment withboth contaminants. This research not only provideda deeper understanding of B. toyonensis SFC 500-1Emetabolic role in Cr(VI) and phenol bioremediationprocess but also allowed us to complete an overviewof the consortium SFC 500-1 behavior. This may contribute to an improvement in its use as a bioremediation strategy and also provides a baseline for furtherresearch.