Using enzymes to remove biofilms of bacterial isolates sampled in the food-industry

Abstract

The aim of this study was to analyze the cleaning efficiency of polysaccharidases and proteolytic enzymes against biofilms of bacterial species found in food industry processing lines and to study enzyme effects on the composition of extracellular polymeric substances (EPS) and biofilm removal in a Clean-in-Place (CIP) procedure. The screening of 7 proteases and polysaccharidases for removal of biofilms of 16 bacterial species was first evaluated using a microtiter plate assay. The alkaline pH buffer removed more biofilm biomass as well as affecting a larger range of bacterial species. The two serine proteases and α-amylase were the most efficient enzymes. Proteolytic enzymes promoted biofilm removal of a larger range of bacterial species than polysaccharidases. Using three isolates derived from two bacterial species widely found in food processing lines (Pseudomonas fluorescens and the Bacillus cereus group), biofilms were developed on stainless steel slides and enzymatic solutions were used to remove the biofilms using CIP procedure. Serine proteases were more efficient in removing cells of Bacillus biofilms than polysaccharidases. However, polysaccharidases were more efficient in removing P. fluorescens biofilms than serine proteases. Solubilization of enzymes with a buffer containing surfactants, and dispersing and chelating agents enhanced the efficiency of polysaccharidases and proteases respectively in removing biofilms of Bacillus and P. fluorescens. A combination of enzymes targeting several components of EPS, surfactants, dispersing and chelating agents would be an efficient alternative to chemical cleaning agents.

Keywords:

• biofilm removal
• enzyme cleaners
• Clean-in-Place (CIP)
• stainless steel
• food
• extracellular polymeric substances (EPS)

View correction statement:

Corrigendum

Acknowledgements

This study was financed by the ‘Agence Nationale de la Recherche’ under the ‘EUREKA’ Project ‘2006 EUKA 00301’. The authors are also grateful to J. Six and L. Wauquier for technical assistance in building the CIP rig and Gwendoline Desailly, Marjorie Danguien, Elise Dozinel, Emma Ben Samou and Aline Delhoute for laboratory assistance.