Open AccessPhylogenetic and functional diversity of bacteria in biofilms from metal surfaces of an alkaline district heating system
Author(s) -
Kjeldsen Kasper Urup,
Kjellerup Birthe Venø,
Egli Konrad,
Frølund Bo,
Nielsen Per Halkjaer,
Ingvorsen Kjeld
Publication year - 2007
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.2006.00255.x
Subject(s) - biology , phylotype , 16s ribosomal rna , biofilm , microbiology and biotechnology , clostridia , bacteria , enrichment culture , library , fosmid , phylogenetic diversity , phylogenetic tree , ecology , metagenomics , gene , genetics
Abstract District heating systems (DHS) are extreme aqueous environments characterized by high temperatures, high pH (9.5–10.0), and low nutrient availability. Culture‐independent and culture‐dependent techniques showed that DHS may nevertheless harbour geno‐ and phenotypically diverse bacterial biofilm communities. Approximately 50% of the cells in biofilms growing on mild steel coupons in rotortorque reactors connected to the return line (40°C) of a Danish DHS were detectable by FISH analysis and thus were probably metabolically active. A bacterial 16S rRNA gene clone library generated from the biofilms was dominated by proteobacterial phylotypes (closely related to known aerobic species) and by phylotypes affiliated to the anaerobic class Clostridia . Anoxic enrichment cultures derived from biofilms primarily contained 16S rRNA gene and dsr AB (encoding major subunits of dissimilatory sulfite reductase) phylotypes affiliated to the latter class. Alkalitolerant and neutrophilic anaerobic bacteria were isolated from the DHS, including novel Gram‐positive and deltaproteobacterial sulfate‐reducers and sulfite‐reducers constituting novel Gram‐positive lineages. In total, 39 distinct 16S rRNA gene phylotypes representing ten classes were identified. The detection of several alkalitolerant, sulfide‐producing, and, thus, potentially biocorrosive species underlines the need to maintain a high water quality in the DHS in order to prevent the proliferation of these species.