Characterization of biofilm formation on a humic material |
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Authors: | A L Rodrigues A G Brito P Janknecht J Silva A V Machado R Nogueira |
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Institution: | Institute for Biotechnology and Bioengineering (IBB), Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4700-057, Braga, Portugal. |
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Abstract: | Biofilms are major sites of carbon cycling in streams. Therefore, it is crucial to improve knowledge about biofilms’ structure
and microbial composition to understand their contribution in the self-purification of surface water. The present work intends
to study biofilm formation in the presence of humic substances (HSs) as a carbon source. Two biofilm flowcells were operated
in parallel; one with synthetic stream water, displaying a background carbon concentration of 1.26 ± 0.84 mg L−1, the other with added HSs and an overall carbon concentration of 9.68 ± 1.00 mg L−1. From the biofilms’ results of culturable and total countable cells, it can be concluded that the presence of HSs did not
significantly enhance the biofilm cell density. However, the biofilm formed in the presence of HSs presented slightly higher
values of volatile suspended solids (VSS) and protein. One possible explanation for this result is that HSs adsorbed to the
polymeric matrix of the biofilm and were included in the quantification of VSS and protein. The microbial composition of the
biofilm with addition of HSs was characterized by the presence of bacteria belonging to beta-Proteobacteria, Cupriavidus metallidurans and several species of the genus Ralstonia were identified, and gamma-Proteobacteria, represented by Escherichia coli. In the biofilm formed without HSs addition beta-Proteobacteria, represented by the species Variovorax paradoxus, and bacteria belonging to the group Bacteroidetes were detected. In conclusion, the presence of HSs did not significantly
enhance biofilm cell density but influenced the bacterial diversity in the biofilm. |
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Keywords: | Humic material Biofilm Flowcell Community composition FTIR |
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