Proteomics and Metabolomics Analyses to Elucidate the Desulfurization Pathway of Chelatococcus sp

PLoS One. 2016 Apr 21;11(4):e0153547. doi: 10.1371/journal.pone.0153547. eCollection 2016.

Abstract

Desulfurization of dibenzothiophene (DBT) and alkylated DBT derivatives present in transport fuel through specific cleavage of carbon-sulfur (C-S) bonds by a newly isolated bacterium Chelatococcus sp. is reported for the first time. Gas chromatography-mass spectrometry (GC-MS) analysis of the products of DBT degradation by Chelatococcus sp. showed the transient formation of 2-hydroxybiphenyl (2-HBP) which was subsequently converted to 2-methoxybiphenyl (2-MBP) by methylation at the hydroxyl group of 2-HBP. The relative ratio of 2-HBP and 2-MBP formed after 96 h of bacterial growth was determined at 4:1 suggesting partial conversion of 2-HBP or rapid degradation of 2-MBP. Nevertheless, the enzyme involved in this conversion process remains to be identified. This production of 2-MBP rather than 2-HBP from DBT desulfurization has a significant metabolic advantage for enhancing the growth and sulfur utilization from DBT by Chelatococcus sp. and it also reduces the environmental pollution by 2-HBP. Furthermore, desulfurization of DBT derivatives such as 4-M-DBT and 4, 6-DM-DBT by Chelatococcus sp. resulted in formation of 2-hydroxy-3-methyl-biphenyl and 2-hydroxy -3, 3/- dimethyl-biphenyl, respectively as end product. The GC and X-ray fluorescence studies revealed that Chelatococcus sp. after 24 h of treatment at 37°C reduced the total sulfur content of diesel fuel by 12% by per gram resting cells, without compromising the quality of fuel. The LC-MS/MS analysis of tryptic digested intracellular proteins of Chelatococcus sp. when grown in DBT demonstrated the biosynthesis of 4S pathway desulfurizing enzymes viz. monoxygenases (DszC, DszA), desulfinase (DszB), and an NADH-dependent flavin reductase (DszD). Besides, several other intracellular proteins of Chelatococcus sp. having diverse biological functions were also identified by LC-MS/MS analysis. Many of these enzymes are directly involved with desulfurization process whereas the other enzymes/proteins support growth of bacteria at an expense of DBT. These combined results suggest that Chelatococcus sp. prefers sulfur-specific extended 4S pathway for deep-desulphurization which may have an advantage for its intended future application as a promising biodesulfurizing agent.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Air Pollutants / analysis*
  • Air Pollutants / isolation & purification
  • Bacterial Proteins / metabolism*
  • Beijerinckiaceae / growth & development
  • Beijerinckiaceae / isolation & purification
  • Beijerinckiaceae / metabolism*
  • Gas Chromatography-Mass Spectrometry
  • Gasoline / analysis
  • Metabolomics*
  • Phylogeny
  • Proteomics*
  • Signal Transduction
  • Sulfur / metabolism*

Substances

  • Air Pollutants
  • Bacterial Proteins
  • Gasoline
  • Sulfur

Grant support

This research work received partial support from the ONGC-CPBT project entitled- “Proteomics study of aromatic hydrocarbons degradation enzymes of some bacterial strains prospecting strategies for environmental bioremediation” and DBT, New Delhi sponsored the research project entitled "Strengthening of biotechnology teaching, training and research in universities and colleges in the Northeast India” granted to AKM. The funders have no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.