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Biofilm samples collected from inside and outside the press and former sections of paper machines in a Northwestern Ontario paper mill for a period of 2 years were characterized microbiologically and electrochemically. Bacterial community profiling was done using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and selected bacterial isolates were identified using 16S rDNA analysis. The bacterial community showed the presence of Proteobacteria, Firmicutes, and Actinobacteria. Sphingomonas sp. was found to be the most common bacterial species, which showed the highest production of extracellular polymeric substances. Bacteria isolated from biofilms showed better adhesion properties than those from water samples. Cyclic voltammetry and electrochemical impedance spectroscopy studies showed that bacteria isolated from biofilms and feed water collected from inside the machine were more easily oxidized than those from outside, suggesting the need for a more rigorous biofilm abatement strategy for inside paper machines. [ABSTRACT FROM AUTHOR]

Abstract: In this study, a Sphingomonas Strain 264 isolated from pulp and paper biofilms was used for electrochemical studies towards applications in biosensor development based on its high ability to produce extracellular polymeric substances (EPS), along with its rapid growth and tendency to flocculate. The Strain 264 biofilm was directly grown on an Au thin film and was studied with a combination of optical and electrochemical methods. The Strain 264 biofilm is stable in a wide potential range from −0.7V to 1.0V versus SCE; it is partially oxidized when the potential is above 1.0V. In addition, the Strain 264 biofilm was used as an immobilization matrix for biosensor fabrication using horseradish peroxidase (HRP) as a model enzyme. Our electrochemical measurements show that the fabricated biosensor based on immobilized HRP in the Strain 264 biofilm exhibits a wide linear range (1–18mM) and a high sensitivity (90μAmM−1) for H2O2 detection, demonstrating that the formed biofilm provides a favourable microenvironment for enzyme to retain its activity. This study has also shown that direct growth of biofilms is a feasible and effective approach for promising applications of biofilms in electrochemical biosensor development. [Copyright &y& Elsevier]