Screening Lactobacillus In Inhibiting Mold And Its Mildew Prevention Effect On Maize

Fusarium is a kind of fungi that can infects a variety of plants（food crops,cash crops,medicinal plants and ornamental plants）,It will cause crop stem rot,stem rot,flower rot,root rot and spike disease in the field,causing a large number of crops wilting death,affect the quality of crops and yield and bring huge economic losses.Fusarium species produce toxins during the infection process,affecting human health.At present,it has been found that there are many kinds of fungi and bacteria in nature that can control the infection of crops and toxins pollute,and reduce the pollution level of biotoxins in agricultural products.Lactobacillus can produce a variety of antibacterial substances in the metabolic process,which has good antibacterial activity,and it has good adsorption of fungi as a biological control agent.This paper screened the lactobacillus with good antibacterial effect and studied its influence on maize mildew control and poison production.The main study results are presented as follows:（1）A total of 105 strains were isolated from 18 samples,96 lactobacillus were determi ned.After identification,the lactobacillus species belong to the following species:Lactobacil lus plantarum,Lactobacillus brevis,Loigolactobacillus coryniformis,Lactobacillus pentosus,Lactobacillus casei,Lactobacillus paracasei,Lactobacillus curvatus,Leuconostoc mesentero ides,Streptococcus thermophilus,Enterococcus durans,Lapidilactobacillus dextrinicus,Com panilactobacillus nodensis,Companilactobacillus hulinensis.（2）With Fusarium graminae,Fusarium sporotrichioides and Fusarium proliferatum as indicator bacterias,the inhibition of lactobacillus on the growth of toxigenic fungi and the removal of the major Fusarium toxins were evaluated by punching method,and the structural changes of hyphae were explored by SEM.The results showed that 28,31 and 33 strains of lactobacillus showed good antibacterial characteristics against the growth of three kinds of toxigenic fungi.Co-culture with cell-free supernatants of lactobacillus showed shrinkage and even breakage on the surface of Fusarium hyphae.LC-MS analysis found that lactobacillus could effectively adsorb ZEN,and the SEM results showed that the cell surface was depressed after ZEN adsorption.（3）The biological characteristics of lactobacillus were studied,a total of nine strains of lactobacillus with good antibacterial effect,no bioamines production and no catalase production were selected.In addition,the nine lactobacillus strains were also screened for acid resistance,bile salt resistance,growth curve and acid production capacity analysis.The results showed that the strain grew faster,and after 0 h-5 h incubation,the strain entered the log growth phase and became a plateau after 12 h.After entering the stable period,p H ranged from 4.38-3.79;All strains can alive in p H of 2,3,4 and bile salt concentration of 0.03%,0.03%,1%,and the strain survival rate decreased with decreasing of p H and the increase of bile salt concentration,Among them,strain11-1 showed a better tolerance.（4）The inhibition of fungi in corn and wheat by cell-free supernatant found that the nine lactobacillus could effectively inhibit the growth of three fungi in corn and wheat and the production of major Fusarium toxins,Among them,lactobacillus 1-10,6-3-1,7-1,9-2,11-1,14-4,16-2 inhibited ZEN and DON well In corn,with inhibition rate of 90%accounted for 70%,and the inhibition rate of FB₁and T-2 toxin was low.In wheat,lactobacillus 2-4,6-3-1,7-1,9-2,11-1,14-4and 16-2 were effective against ZEN,with inhibition rate of 50%accounted for 90%,and inhibition rate of 80%accounted for 70%to FB₁,2-4,1-10,6-3-1,6-3-2,11-1,16-2,respectively,but less for DON and T-2 toxins.