Immobilized enzyme on a plastic surface : how to weaken a biofilm

Biofilms represent a sessile community where cells are irreversibly attached to a substrate, to an interface or to other cells. In comparison with organisms in the planktonic form, cells that aere included into biofilms present different phenotype, gene transcription and growth rate. These features are responsible of the great resistance and aggression of biofilm. Cells into biofilm are immersed into an extracellular polymeric matrix (EPS) which is self-produced and form of 97% of water and 3% of polysaccharides, proteins, nucleic acid, humic substances, metabolites and cellular residues. EPS plays an important role in the formation of biofilm because it alloes the adhesion, aggregation of bacterial cells, biofilm’s cohesion, water retention, enzyme activity and cellular communication. With the intent of developing methods for the preparation of antifouling surfaces, we have been studying the role of protease (alpha-chymotrypsin) as biochemical agent for preventing the growth of biofilm on polyethylene. This protease cleaves peptide amide bonds where the carboxyl side of the amide bond is a tyrosine, tryptophan or phenylalanine. In our preliminary studies alpha-chymotrysin has been immobilized on polyethylee coupons preventively coated with polyethyleneimine (PEI) by crossing-linking with glutaraldehyde of the enzyme to PEI. Methoxypoly(ethylene glycol) (5 KDa) was also added during the cross-linking reaction as enzyme stabilizing additive. The effect of immobilized alpha-chymotrypsin on biofilm growth was evaluated comparing the growth of a biofilm of Escherichia coli cells in a CDC reactor for 48 H on polyethylene coupons prepared with or without (control) enzyme. The results show that the growth curve of E. coli is similar in term of biomass between the control and the enzyme-coated coupon, but there is a visible difference in terms of resistance. This preliminary result indicates that the use of enzymes as agents to weak a biofilm can be an approach that deserves to be investigated for developing new materials with antifouling properties.