Inhibitory effects of enterococci on the production of hydrogen sulfide by hydrogen sulfide-producing bacteria in raw meat

Abstract

Applying competitive exclusion micro-organisms to control hydrogen sulfide (H₂S) gas produced by hydrogen sulfide-producing bacteria (SPB) in chicken meat. Five SPB strains, isolated from animal by-products, were used for screening lactic acid bacteria (LAB) that can inhibit the production of H₂S by SPB in trypticase soy broth supplemented with L-cysteine (TSB-L-cys). A sensitive and accurate test strip method was developed for H₂S determination in real time. One LAB strain, isolate L86, from cheese whey, demonstrated the highest inhibitory activity against the production of H₂S by SPB. The isolate L86 was confirmed as Enterococcus faecium that does not possess genes encoding for vancomycin resistance based on PCR analysis. Enterococcus faecium strain L86 reduced (P < 0·05) the yield of H₂S upto 51·2% in 10 h at 35°C in TSB-L-cys medium. In fresh chicken meat, the yield of H₂S produced by the artificially inoculated SPB was reduced (P < 0·05) by 48·6, 49·7 and 69·8% in 10 h at 35, 30 and 25°C, respectively. Enterococcus faecium strain L86 also reduced (P < 0·05) by 53·8% on the yield of H₂S produced by the indigenous SPB in partially spoiled chicken meat at 35°C for 10 h. Enterococcus faecium strain L86 is effective on inhibiting the production of H₂S by SPB. The application of this biological agent to raw animal by-products will provide a safer working environment in rendering processing plants and produce higher-quality rendered products.