title: Culture-independent analysis of desulfovibrios in the human distal colon of healthy, colorectal cancer and polypectomized individuals.
abstract: The production of hydrogen sulphide, an end product of metabolism by the sulphate-reducing bacteria (SRB) has been cited as a potential aetiological agent in gastrointestinal disease. Quantitative PCR (Q-PCR) assays to enumerate desulfovibrios from two gastrointestinal disease groups: colorectal cancer (CRC) n=27 and polypectomized individuals (PP) n=27, and two healthy control groups, elderly (H1) n=8 and young adults (H2) n=30 was performed. Analysis of Desulfovibrio sp. diversity using the dissimilarity sulphite reductase (dsrAB) gene as a molecular marker was also undertaken. Q-PCR detected Desulfovibrio sp. in all samples and no significant difference was observed for PP, H1, H2 with gene copy numbers of Desulfovibrio sp. averaging at 10(6) g(-1) of faeces. Significantly reduced numbers of Desulfovibrio sp. were observed for CRC (10(5) g(-1)) compared with both PP and H2 groups (P<0.05). Diversity analysis indicated that a low Desulfovibrio sp. diversity and the predominance of Desulfovibrio piger was a feature of both healthy and disease groups. In addition, a dsrAB gene sequence distantly related to a Gram-positive SRB was also recovered, highlighting the importance of cultivation-independent techniques for furthering our understanding of the diversity of the human gastrointestinal ecosystem.
authors.affiliation: Alimentary Pharmabiotic Centre, University College Cork, National University of Ireland, Cork, Ireland.
authors.forename: Pauline D
authors.initials: PD
authors.lastname: Scanlan
authors.forename: Fergus
authors.initials: F
authors.lastname: Shanahan
authors.forename: Julian R
authors.initials: JR
authors.lastname: Marchesi
mesh_terms: D000328:Adult; D000368:Aged; D044822:Biodiversity; D003106:Colon / Q000382:microbiology*; D003111:Colonic Polyps / Q000382:microbiology*; D015179:Colorectal Neoplasms / Q000382:microbiology*; D004269:DNA, Bacterial / Q000235:genetics; D003901:Desulfovibrio / Q000235:genetics* / Q000302:isolation & purification; D005243:Feces / Q000382:microbiology; D005260:Female; D018628:Gene Dosage; D006801:Humans; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D055815:Young Adult
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S