roqueforti s.l. in Silage: in vitro and in vivo Evaluation

In Belgium, silages are often infected by Penicillium roqueforti sensu lato (s.l.). These 13 toxigenic fungi are well adapted to silage conditions, and their prevention during feed-out is 14 difficult. Bacillus velezensis strain NRRL B-23189 has been reported to inhibit P. roqueforti s.s. 15 conidiospore germination in vitro by the production of lipopeptides. In the present study, the 16 antagonistic effect of this B. velezensis strain towards P. roqueforti s.l. was evaluated in vitro and in 17 vivo. In vitro, corn silage conditions were simulated, and the impact of B. velezensis culture 18 supernatant or cell suspension on P. roqueforti s.l. growth, conidiospore germination and survival 19 and roquefortine C production was evaluated. The antagonism was promising, but growth of 20 B. velezensis in corn silage infusion was poor. An in vivo experiment with microsilos containing a 21 mixture of perennial ryegrass and white clover artificially contaminated with P. roqueforti s.l. was 22 carried out to determine if B. velezensis cell suspension could be used as an antagonistic silage 23 inoculant. The B. velezensis cell suspension applied was unsuccessful in reducing P. roqueforti s.l. 24 numbers at desiling after 56 days compared to no additive application. However, feed-out of the 25 silage was not simulated, so it remains elusive whether or not B. velezensis exerts antagonistic 26 activity during this phase. 27