Molecular characterization of sulfidogenic communities among pristine and polluted sites based on the dissimilatory sulfite reductase genes (DSRAB).

摘要

Sulfate-reducing bacteria (SRB) are considered major biogeochemical drivers in anoxic environments. Transformation of petroleum-derived contaminants has been demonstrated coupled to biological sulfate reduction. Our objective is to develop a molecular tool for characterizing diversity and distribution of sulfidogenic communities to track specific SRB populations and, ultimately, monitoring natural attenuation conducted by SRB in situ. In this project, the dissimilatory sulfite reductase genes (dsrAB ), encoding the final enzyme of sulfate respiration was used as a molecular biomarker to track SRB. Initially, the dsrAB genes were characterized for a collection of novel isolates and consortia capable of degrading hydrocarbons under sulfidogenic conditions to set the basis for studying SRB in disturbed environments (Chapter II). In a second set of analyses, DSR diversity was measured using the terminal restriction fragment length polymorphism (TRFLP) technique to achieve a more comprehensive representation of the natural sulfidogenic communities (Chapter III). Finally, a global assessment of SRB population structure in polluted and pristine sediments from 4 continents was accomplished using TRFLP (Chapter IV). Several sequences corresponding to those novel hydrocarbon-degrading SRB were retrieved from a contaminated river in South Korea. Our dsr-TRFLP analyses have revealed the extent of the genetic diversity and distribution of dsrAB among global polluted sites and Neotropical mangroves. Although relevant information has been gathered in this document, the extent of the diversity and distribution of natural sulfidogenic communities remain mostly uncharacterized. We defined dsr-TRFLP as a molecular tool coupling TRFLP, clonal sequencing, and community cluster analysis based on dsrAB genes for rapid and sensitive exploration of SRB. This molecular approach have provided insights about the heterogeneity, structure, diversification, and biogeography of sulfidogenic communities that can assist in accounting and understanding ecological phenomenon, physiological responses, environmental quality, and management policies.