Study On The Subtilin Produced By Bacillus Subtilis FB123

In the present study,subtilin produced by Bacillus subtilis FB123 were purified and characterized,and their primary structures were studied.The characteristics and the antimicrobial spectrum of the crude subtilin were analyzed.The results showed that the crude subtilin kept its activity in a broad range of pH value and had the optimum pH of 6.0.The crude subtilin also showed a stronger thermostability and had the optimal culture temperature at 40℃.It can be partly inactivated by proteinase.The activity of crude subtilin could be partly improved by Na⁺,Fe²⁺,Zn²⁺and Ca²⁺,partly inhibited by Mg²⁺,Al³⁺,K⁺and Cu²⁺Organic Solvents can strongly inhibit its activity.The antimicrobial spectrum tests showed that the crude subtilin exhibited stronger inhibition to both gram negative and positive bacteria used and had a weak inhibition to part fungi tested.The crude subtilin was purified by ammonium sulfate precipitation,Sephacryl S-200,DEAE Sepharose Fast Flow chromatography and four components of subtilin(P2,P3-2,P4,P5)was obtained.P3-2 was identified to be homogenous with SDS-PAGE,and its molecular weight and pI value were of 14.8 kDa and 3.64;15 amino acids residues of its N-terminal was measured by Edman degradation method,the secquence was N-DREISEGSVDQSSWC-15;The analysis based on periodic acid schiff reaction(PAS) and Sudan B lipid staining suggested P3-2 might be a lipoprotein,but not a glycoprotein; P3-2 showed insensitive to proteinase;and kept activity within wide pH value;it showed stronge thermal stability and with the optimal temperature of 30℃.The activity of P3-2 could be partly inhibited by K⁺,Zn²⁺,Ca²⁺,Na⁺and partly improved by Al³⁺,Mg²⁺,Fe²⁺,Cu²⁺;P3-2showed broad ranges of anti-microbial activities not only to some gram-positive bacteria but also some fungi;but it showed no inhibition to Ecoli.Supplementary study on the P2 component:1.the 8 amino acid residues in the N-terminal of P2 were measured,it was N-(Q,M)KPINISD-8;2.the anti-fungi activity of P2 component was studied,the result showed that the P2 showed stronger anti-fungi activity than the crude subtilin and P3-2 components in the same concentration.