title: Phylogenetic diversity of transition and anoxic zone bacterial communities within a near-shore anoxic basin: Nitinat Lake.
abstract: At two stations surveyed in Nitinat Lake, a approximately 200-m-deep anoxic tidal fjord, sulfide was detected as close as 15 m from the surface. Biological characterization, determined from small subunit ribosomal RNA gene sequencing, of the chemocline and anaerobic zone revealed many sequences related to sulfur-oxidizing bacteria, suggesting that sulfur cycling is a dominant process. gamma- and epsilon-Proteobacteria related to thiotrophic symbionts, as well as Chlorobium sp., dominated the transition zone. These are expected to play a role in dark and phototrophic CO(2) fixation, respectively. epsilon-Proteobacteria phylotype abundance increased with depth, eventually comprising 69-97% of all sequences recovered from the anoxic zone. The vast majority (74%) of these phylotypes were affiliated with a novel Acrobacter sp. group (NITEP5). Quantification of NITEP5 revealed that up to 2.8 x 10(5) cells ml(-1) were present in the anoxic zone. Surprisingly, although sequences related to known sulfate-reducing bacteria were recovered from the transition zone, quantification of the dsr gene and (35)SO(4)(2-) uptake tests suggest that sulfate-reduction within the water column is negligible. Overall, sequence diversity between different vertical zones was high, although the spatial segregation of gamma-Proteobacteria, Chlorobi, and epsilon-Proteobacteria did not appear to vary significantly between seasons.
authors.affiliation: Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, BC, Canada.
authors.forename: Jana
authors.initials: J
authors.lastname: Schmidtova
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Hallam
authors.forename: Susan A
authors.initials: SA
authors.lastname: Baldwin
mesh_terms: D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D044822:Biodiversity; D002170:Canada; D041883:Chlorobium / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D020565:Epsilonproteobacteria / Q000145:classification / Q000302:isolation & purification; D005618:Fresh Water / Q000382:microbiology*; D020563:Gammaproteobacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D005798:Genes, Bacterial; D014644:Genetic Variation; D005843:Geography; D010802:Phylogeny