S. Kurissery, N. Kanavillil, L. Davey, K.T. Leung, H. Schraft, A. Chen, N. Low, L. Truelstrup-Hansen, A. Paulsen, and D. Pink (Canada)
Biofilm; Pulp and Paper; DGGE; Electrochemistry
Biofilms collected from a paper mill in Northwestern Ontario were characterized with respect to physical, chemical, microbiological and electrochemical properties. Biofilm samples were collected from inside and outside of the paper machines during extended periods of maintenance shutdown and were analysed for properties such as pH, texture, total culturable bacterial counts, bacterial community structure, adhesion studies using biofilm bacterial isolates and adsorption and desorption properties using cyclic voltammetry and electrochemical impedance spectroscopy (EIS). Water samples collected at the same sampling points were also analysed for pH, temperature and total culturable microbial load. The results showed a higher bacterial count (105 -108 cfu/ml) in biofilms than in the water samples (102 -106 cfu/ml). The pH of biofilms collected from the inside surfaces of paper machines was lower (2.9-5.5) than that from the outside surfaces (6.4-6.9). The bacterial community structure studied using nucleic acid finger printing (DGGE) techniques and 16S rDNA profiling revealed the presence of several groups of bacteria; Proteobacteria, firmicutes and actinobacteria. Sphingomonas sp. Was found to be the most common bacterial species that also produced the highest volume of extracellular polymeric substances. Biofilm formation assay using bacterial isolates showed the presence of good and weak biofilm formers. Finally, the cyclic voltammetry studies showed that biofilms from inside the machine and the bacteria isolated from inside water were easier to oxidize than those from outside the machine and outside water samples.
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