Removal of microbial multi-species biofilms from the paper industry by enzymatic treatments

Abstract

This study aimed to characterize biofilms from the paper industry and evaluate the effectiveness of enzymatic treatments in reducing them. The extracellular polymeric substances (EPS) extracted from six industrial biofilms were studied. EPS were mainly proteins, the protein to polysaccharide ratio ranging from 1.3 to 8.6 depending on where the sampling point was situated in the paper making process. Eight hydrolytic enzymes were screened on a 24-h multi-species biofilm. The enzymes were tested at various concentrations and contact durations. Glycosidases and lipases were inefficient or only slightly efficient for biofilm reduction, while proteases were more efficient: after treatment for 24 h with pepsin, Alcalase® or Savinase®, the removal exceeded 80%. Savinase® appeared to be the most adequate for industrial conditions and was tested on an industrial biofilm sample. This enzyme led to a significant release of proteins from the EPS matrix, indicating its potential efficiency on an industrial scale.

Keywords:

• paper mill biofilms
• extracellular polymeric substances (EPS)
• protease
• multi-methods extraction
• enzymatic removal

Acknowledgements

This study was financed by the ‘Agence Nationale pour la Recherche’ under the PRECODD 2008 project ‘ANR-08-ECOT-003’. The authors are sincerely grateful to Armand Klem (Norske Skog) for technical support and Caroline Segaërt-Nicoud (LBAE) for laboratory assistance.