title: Influence of sulfide and temperature on species composition and community structure of hot spring microbial mats.
abstract: In solfataric fields in southwestern Iceland, neutral and sulfide-rich hot springs are characterized by thick bacterial mats at 60 to 80 degrees C that are white or yellow from precipitated sulfur (sulfur mats). In low-sulfide hot springs in the same area, grey or pink streamers are formed at 80 to 90 degrees C, and a Chloroflexus mat is formed at 65 to 70 degrees C. We have studied the microbial diversity of one sulfur mat (high-sulfide) hot spring and one Chloroflexus mat (low-sulfide) hot spring by cloning and sequencing of small-subunit rRNA genes obtained by PCR amplification from mat DNA. Using 98% sequence identity as a cutoff value, a total of 14 bacterial operational taxonomic units (OTUs) and 5 archaeal OTUs were detected in the sulfur mat; 18 bacterial OTUs were detected in the Chloroflexus mat. Although representatives of novel divisions were found, the majority of the sequences were >95% related to currently known sequences. The molecular diversity analysis showed that Chloroflexus was the dominant mat organism in the low-sulfide spring (1 mg liter(-1)) below 70 degrees C, whereas Aquificales were dominant in the high-sulfide spring (12 mg liter(-1)) at the same temperature. Comparison of the present data to published data indicated that there is a relationship between mat type and composition of Aquificales on the one hand and temperature and sulfide concentration on the other hand.
authors.affiliation: Prokaria Ltd., Keldnaholt, IS-112 Reykjavik, Iceland.
authors.forename: S
authors.initials: S
authors.lastname: Skirnisdottir
authors.forename: G O
authors.initials: GO
authors.lastname: Hreggvidsson
authors.forename: S
authors.initials: S
authors.lastname: Hjörleifsdottir
authors.forename: V T
authors.initials: VT
authors.lastname: Marteinsson
authors.forename: S K
authors.initials: SK
authors.lastname: Petursdottir
authors.forename: O
authors.initials: O
authors.lastname: Holst
authors.forename: J K
authors.initials: JK
authors.lastname: Kristjansson
mesh_terms: D001105:Archaea / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D018407:Bacterial Physiological Phenomena; D003001:Cloning, Molecular; D017753:Ecosystem; D005618:Fresh Water; D020459:Genes, rRNA / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D012335:RNA, Ribosomal / Q000235:genetics; D017422:Sequence Analysis, DNA; D013440:Sulfides / Q000378:metabolism*; D013696:Temperature; D014871:Water Microbiology
chemical_list: D012335:RNA, Ribosomal; D013440:Sulfides