Screening Of Antagonistic Strains Against Trichothecium Roseum And Identification Of Its Inhibition Substances

Antimicrobial peptides(AMPs)are biologically active molecules produced by a wide variety of organisms as an essential component of their innate immune response.These molecules have been considered as potential therapeutics because of their broad-spectrum activities and proven ability to evade antimicrobial resistance.AMPs can be used in several biotechnological applications with different purposes.In order to further explore new antimicrobial peptide resources,we screened a antagonistic bacillus strain that can inhibited the growth of Trichothecium roseum from 20 Bacillus strains which were isolated from stale potato vermicelli,futhur identification and purified antimicrobial active substance from the fermentation broth of the antagonistic bacillus strain.Study provides valuable genetic resources for cultivating new disease-resistant cultivars,and lays the foundation for the development and research of new biological pesticides.The main results obtained are as follows:1 Screening a highly active antagonistic strain against T.roseum.Screened a Bacillus strain B10 that can inhibition against T.roseum from 20 Bacillus strains which were isolated from stale potato vermicelli,and identified as B.pumilus HN-10 based on 16 S r RNA gene sequence analysis,Genebank number was KT003256.1.The strain has been collected in China General Microbiological Culture Collection Center(CGMCC No.15031).2 Determined the antimicrobial spectrum of B.pumilus HN-10.To determined the spectrum of B.pumilus HN-10,E.coli,Staphylococcus aureus,Salmonella,T.roseum,Penicillium visidicatum,Aspergillus niger,Absidia corymbifera and Alternaria alternate as test microbial,and the result showed that B.pumilus HN-10 can only inhibited the growth of T.roseum.3 Purified two antifungal peptides.Three components A,B,C with strong inhibition against T.roseum were obtained by using ammonium sulfate precipitation,macroporous adsorbent resin AB-8,Sephadex G-100 chromatography,and reversed-phase high-performance liquid chromatography from B.pumilus HN-10 fermentation broth.4 Physicochemical properties of antimicrobial substances.The physical and chemical properties of antimicrobial crude extract of B.pumilus HN-10 showed that the crude extract had the properties of thermal stability,enzyme stability and p H stability and had great potential in plant biological control.5 Identified the structures of two antifungal peptides.The structures of componts A,B and C were analyzed by HPLC-MALDI-TOF-MS/MS.Finally,it was confirmed that component A was an antifungal peptide P-1 with 11 amino acids and molecular weight of 1142.28 Da.The amino acid sequence PLSSPATLNSR;components B and C were identified as the same compound,containing 15 amino acids,a molecular weight of 1149.14 Da antifungal peptide P-2,the amino acid sequence of GGSGGGSSGGSIGGR.The amino acid sequence of P-1 and P-2 was lower than that of other known antimicrobial peptides with the highest similarity of 41.66% and 45% respectively.These findings confirmed that both the peptides obtained were novel.Besides,both P-1 and P-2 exhibited strong antifungal activity against T.roseum with minimum inhibitory concentrations starting from 1 ?g/m L.