Inhibition of Listeria monocytogenes by defined lactic microflora in gnotobiotic silages of lucerne,fescue, ryegrass and maize — Influence of dry matter and temperature

The development of L. monocytogenes was studied in gnotobiotic silages of four plant species (ryegrass, fescue, lucerne, maize) with various dry matter concentrations and incubation temperatures. The microflora of these silages was perfectly defined and included Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus casei, Pediococcus spp., Enterobacter liquefaciens and Clostridium tyrobutyricum. The results show that in silages of good quality not only is there no development of L. monocytogenes, but the cells initially present are eliminated. It is therefore most unlikely that a silage of good quality with a pH lower than 5 plays a contaminating role. The hypothesis according to which silages, especially those of bad quality, contain factors favouring contamination seems to be more plausible.