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Biogeochemical activity of microbial biofilms in the water column overlying uranium mine tailings
Author(s) -
Bondici V.F.,
Khan N.H.,
Swerhone G.D.W.,
Dynes J.J.,
Lawrence J.R.,
Yergeau E.,
Wolfaardt G.M.,
Warner J.,
Korber D.R.
Publication year - 2014
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/jam.12593
Subject(s) - biofilm , tailings , proteobacteria , firmicutes , environmental chemistry , biogeochemical cycle , bacteroidetes , microbial population biology , actinobacteria , ferrous , chemistry , biology , bacteria , 16s ribosomal rna , organic chemistry , genetics
Aims To describe microbial diversity, biofilm composition and biogeochemical potential within biofilms in the water overlying uranium tailings characterized by high pH , high metal concentration and low permeability. Methods and Results To estimate microbial diversity in biofilms formed in water columns overlying uranium mine tailings, culture‐dependent and culture‐independent methods were employed. High‐throughput sequencing revealed the presence of 11 phyla; however, the majority of the sequences were affiliated with four major lineages ( P roteobacteria , B acteroidetes , A ctinobacteria and F irmicutes) as confirmed by culture‐based methods. Dominant phylotypes were closely related to methylotrophs ( M ethylobacterium ) and bacterial groups able to utilize complex hydrocarbons ( A quabacterium and D echloromonas ). Microbial diversity in biofilms from the 13 m depth was significantly different that in biofilms from 1 to 41 m ( P < 0·05). Phylotypes closely related to iron‐reducing bacteria were identified at each depth; whereas sulphate‐, thio‐sulphate‐, sulphite‐ and sulphur‐reducing bacteria, at low abundance, were only detected at lower depths. Confocal scanning laser microscopy ( CSLM ) was used to investigate polymer quantity and composition of the biofilm components, and principal component analysis of the CLSM data revealed that the relative abundance of α ‐L‐fucose and N‐acetyl‐glucosamine/lipopolysaccharide residues separated tailings–water interface biofilms from those from other depths. Reduced (ferrous) iron was detected within all the biofilm samples examined by scanning X ‐ray transmission microscopy. Conclusions Microbial communities within the water column covering a highly alkaline uranium tailings body form biofilms with microenvironments where iron reduction takes place. Significance and Impact of the Study This study demonstrates the biogeochemical potential of microbial biofilm communities in the water column covering an alkaline uranium tailings body; specifically, the nature of the bacterial groups detected ( Aquabacterium , Dechloromonas ) and the presence of reduced iron suggest that complex hydrocarbons are available for bacterial growth and geochemical change, such as iron reduction, can occur even though the system bulk phase is predominantly oxic.