title: Molecular quantification of sulfate-reducing microorganisms (carrying dsrAB genes) by competitive PCR in estuarine sediments.
abstract: In this study, we describe a competitive polymerase chain reaction (PCR) for the quantification of the sequences of dsrAB in sulfate-reducing microorganisms. We used the dsr1F/dsr4R set of primers, previously designed by Wagner et al. (1998), and a competitor sequence was constructed from the dsrAB genes of Desulfovibrio vulgaris. The detection limit of competitive PCR corresponded to 45 copies of the dsrAB genes per ng of extracted DNA, and most of the dsrAB sequences amplified and cloned from DNA extracted from Seine estuary sediments were amplified with a similar efficiency. Competitive PCR was then used to assess the abundance of dsrAB genes in the total DNA extracted from the sediment of the Seine estuary mudflats. We observed that the abundance of dsrAB coincided with the variation in the sulfate reduction rate with the depth of the sample, confirming the importance of 'dsrAB' sulfate-reducing microorganisms in sulfidogenesis in anoxic environments. We obtained values ranging from 0.045x10(3) to 6.63x10(3) copies of dsrAB per ng of extracted DNA, and values of the sulfate reduction rate ranging from 35 to 158 nmol cm(-3) day(-1). These results are similar to those obtained in other studies using molecular biology techniques.
authors.affiliation: LMDF-UPRES, UFR des Sciences, Université de Rouen, Mont Saint Aignan, France. julie.leloup@univ-rouen.fr
authors.forename: Julie
authors.initials: J
authors.lastname: Leloup
authors.forename: Laurent
authors.initials: L
authors.lastname: Quillet
authors.forename: Cécile
authors.initials: C
authors.lastname: Oger
authors.forename: Dominique
authors.initials: D
authors.lastname: Boust
authors.forename: Fabienne
authors.initials: F
authors.lastname: Petit
mesh_terms: D017931:DNA Primers; D004269:DNA, Bacterial / Q000032:analysis / Q000302:isolation & purification; D019015:Geologic Sediments / Q000382:microbiology*; D050885:Hydrogensulfite Reductase / Q000235:genetics* / Q000378:metabolism; D016133:Polymerase Chain Reaction / Q000379:methods*; D015203:Reproducibility of Results; D045483:Rivers / Q000382:microbiology*; D013431:Sulfates / Q000378:metabolism*; D016999:Sulfur-Reducing Bacteria / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification
chemical_list: D017931:DNA Primers; D004269:DNA, Bacterial; D013431:Sulfates; D050885:Hydrogensulfite Reductase