Journal of Antimicrobial Agents

Antimicrobial Activity of Intrinsic Antimicrobial Polymers Based on Poly((tertbutyl-amino)-methyl-styrene) Against Selected Pathogenic and Spoilage Microorganisms Relevant in Meat Processing Facilities

Abstract

Braun C, Dohlen S, Ilg Y, Brodkorb F, Fischer B, et al.

Objective: Antimicrobial materials are used as a possible approach to improve hygienic conditions in the food industry. The aim of this study was the investigation of the antimicrobial activity of the homopolymer of poly((tertbutyl- amino)-methyl-styrene) (poly(TBAMS)) and of the copolymer poly(TBAMS:acrylonitrile) [1:1] against microorganism present on meat processing equipment. Method: Antimicrobial polymers were characterized by Fourier transform infrared spectroscopy and differential scanning calorimetry analysis. The antimicrobial activity against various pathogenic and spoilage bacteria (S. aureus, E. coli, L. monocytogenes, Salmonella spp., Pseudomonas spp., B. thermosphacta) was determined using a modified test method based on the Japanese Industrial Standard JIS Z 2801: 2000. Furthermore, the influence of high initial bacterial counts (up to 8.9 log10 cfu/ml) as well as the exposure of bacteria in mixed cultures on the antimicrobial activity was evaluated. Results: Spectroscopy identified the homopolymer poly(TBAMS) as well as a successful copolymerization with acrylonitrile. Results of antimicrobials tests showed significant reductions of bacterial counts on both polymers compared with the reference material of microorganisms in pure culture after 2 hour at 35°C. L. monocytogenes, E. coli and S. aureus were reduced to the detection limit (>4.2 log10-units). P. fluorescens was less sensitive to poly(TBAMS)-based films, especially to the copolymer. The homopolymer offers slightly higher activity than the copolymer, but glass transition temperature was lower. Tests with mixed cultures affirmed the dependency of activity on bacteria species. A tendency of higher antimicrobial activity against gram-positive was observed, if high initial counts were used; however, significant reduction of gram-negative were still determined. Conclusion: Poly(TBAMS)-films show excellent antimicrobial properties against microorganisms relevant in meat processing facilities, and the implementation of those surfaces could contribute to improving the hygienic conditions during production and processing.