생물방제균 Bacillus subtilis YB-70이 생산하는 항진균성 항생물질의 분리 및 구조결정

A potential biocontrol bacterium, YB-70 was isolated from a rhizosphere in suppressive soil and identified as a strain of Bacillus subtilis. In several biochemical and in vitro antibiosis tests on Fusarium solani with the culture filterates from B. subtilis YB-70, we found that antifungal mechanism of B. subtilis YB-70 was mediated by antibiotic substances produced from the bacterium. These antifungal substances were appeared to be hear-resistant, micromolecular, and ethy alcohol soluble. Antifungal agents produced by B. subtilis YB-70 showed strong inhibified against root-rotting fungi F. solani in in vivo pot test. An antifungal substance. YBS-1s, was purified from the culture broth of B. subtilis YB-70 by isoelectronic precipitation, silica gel column chromatography and Sephadex LH-20 column chromatography analysis by Fab-MASS, $^{1}$H-NMR, $^{13}$C-NMR, DEPT, and amino acid analyzer revealed that the YBS-1A was a peptide antibiotics of iturin class containing seven amino acids from five different groups, and the other(YBS-1B) was an analogue of iturin group composed of 11 amino acids with larher molecular weight of about 1, 500 dalton, which was lager than that of iturin A.