Dominance of sphingomonads in a copper-exposed biofilm community for groundwater treatment.

Grupo de Microbiología Ambiental (Environmental Microbiology Research Group), Instituto del Agua, Escuela Superior de Ingenieros de Caminos, Canales y Puertos, Universidad de Granada, 18071 Granada, Spain.
Microbiology (Impact Factor: 2.84). 03/2007; 153(Pt 2):325-37. DOI: 10.1099/mic.0.2006/002139-0
Source: PubMed

ABSTRACT The structure, biological activity and microbial biodiversity of a biofilm used for the removal of copper from groundwater were studied and compared with those of a biofilm grown under copper-free conditions. A laboratory-scale submerged fixed biofilter was fed with groundwater (2.3 l h(-1)) artificially polluted with Cu(II) (15 mg l(-1)) and amended with sucrose (150 mg l(-1)) as carbon source. Between 73 and 90 % of the Cu(II) was removed from water during long-term operation (over 200 days). The biofilm was a complex ecosystem, consisting of eukaryotic and prokaryotic micro-organisms. Scanning electron microscopy revealed marked structural changes in the biofilm induced by Cu(II), compared to the biofilm grown in absence of the heavy metal. Analysis of cell-bound extracellular polymeric substances (EPS) demonstrated a significant modification of the composition of cell envelopes in response to Cu(II). Transmission electron microscopy and energy-dispersive X-ray microanalysis (EDX) showed that copper bioaccumulated in the EPS matrix by becoming bound to phosphates and/or silicates, whereas copper accumulated only intracytoplasmically in cells of eukaryotic microbes. Cu(II) also decreased sucrose consumption, ATP content and alkaline phosphatase activity of the biofilm. A detailed study of the bacterial community composition was conducted by 16S rRNA-based temperature gradient gel electrophoresis (TGGE) profiling, which showed spatial and temporal stability of the species diversity of copper-exposed biofilms during biofilter operation. PCR reamplification and sequencing of 14 TGGE bands showed the prevalence of alphaproteobacteria, with most sequences (78 %) affiliated to the Sphingomonadaceae. The major cultivable colony type in plate counts of the copper-exposed biofilm was also identified as that of Sphingomonas sp. These data confirm a major role of these organisms in the composition of the Cu(II)-removing community.

  • [Show abstract] [Hide abstract]
    ABSTRACT: The pyrosequencing technique was used to evaluate bacterial community structures in sediment and surface water samples taken from Nanxi River receiving effluents from a paper mill and a farmhouse hotel, respectively. For each sample, 4,610 effective bacterial sequences were selected and used to do the analysis of diversity and abundance, respectively. Bacterial phylotype richness in the sediment sample without effluent input was higher than the other samples, and the surface water sample with addition of effluent from the paper mill contained the least richness. Effluents from both the paper mill and farmhouse hotel have a potential to reduce the bacterial diversity and abundance in the sediment and surface water, especially it is more significant in the sediment. The effect of the paper mill effluent on the sediment and surface water bacterial communities was more serious than that of the farmhouse hotel effluent. Characterization of microbial community structures in the sediment and surface water from two tributaries of the downstream river indicated that various effluents from the paper mill and farmhouse hotel have the similar potential to decrease the natural variability in riverine microbial ecosystems.
    Microbial Ecology 07/2014; · 3.12 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This study focused on identification of denitrifiers that can be used to achieve microbial self-healing concrete. By using heat treatment and minimal medium, 9 denitrifying strains were isolated from soil. Upon identification of the strains, their capability of handling dehydration stress was investigated. Qualifying 7 strains were further investigated at N:P ratio of 70:1. Finally, 2 strains, Pseudomonas aeruginosa and Diaphorobacter nitroreducens, were selected and investigated at pH 7, pH 9.5 and pH 13 with and without protection. As a protective carrier diatomaceous earth and expanded clay were used. Significant activity observed at pH 9.5 and with protection both strains could survive pH 13 for 14 days and reduced 20-30 mg/L NO 3 -in 4 days after the pH adjustment to ~10. Overall, the results indicated that Pseudomonas aeruginosa and Diaphorobacter nitroreducens can resist mild heat, dehydration, starvation and relatively alkali environment, which are the main concerns in use of bacteria for concrete structures.
    Advances in Bio-Informatics, Bio-Technology and Environmental Engineering, Birmingham; 11/2014
  • [Show abstract] [Hide abstract]
    ABSTRACT: Mining activities pose severe environmental risks worldwide, generating extreme pH conditions and high concentrations of heavy metals, which can have major impacts on the survival of organisms. In this work, pyrosequencing of the V3 region of the 16S rDNA was used to analyze the bacterial communities in soil samples from a Brazilian copper mine. For the analysis, soil samples were collected from the slopes (geotechnical structures) and the surrounding drainage of the Sossego mine (comprising the Sossego and Sequeirinho deposits). The results revealed complex bacterial diversity, and there was no influence of deposit geographic location on the composition of the communities. However, the environment type played an important role in bacterial community divergence; the composition and frequency of OTUs in the slope samples were different from those of the surrounding drainage samples, and Acidobacteria, Chloroflexi, Firmicutes, and Gammaproteobacteria were responsible for the observed difference. Chemical analysis indicated that both types of sample presented a high metal content, while the amounts of organic matter and water were higher in the surrounding drainage samples. Non-metric multidimensional scaling (N-MDS) analysis identified organic matter and water as important distinguishing factors between the bacterial communities from the two types of mine environment. Although habitat-specific OTUs were found in both environments, they were more abundant in the surrounding drainage samples (around 50 %), and contributed to the higher bacterial diversity found in this habitat. The slope samples were dominated by a smaller number of phyla, especially Firmicutes. The bacterial communities from the slope and surrounding drainage samples were different in structure and composition, and the organic matter and water present in these environments contributed to the observed differences.
    Antonie van Leeuwenhoek 08/2014; · 2.07 Impact Factor


Available from