title: The supernatant of Bacillus pumilus SQR-N43 has antifungal activity towards Rhizoctonia solani.
abstract: For clarification of the antagonistic mechanism of Bacillus pumilus SQR-N43 (N43) against Rhizoctonia solani Q1, production of antibiotics by N43 was determined, and the effect of the antibiotics on the pathogen mycelium was microscopically observed. Further more, the control efficiencies of the antifungal compounds on damping-off disease were investigated. The results obtained are listed as follows: N43 produced antibiotic substances towards R. solani Q1 at logarithmic growth phase. The antibiotics caused hyphal deformation and enlargement of cytoplasmic vacuoles in R. solani Q1 mycelia. 70% saturation of ammonium sulfate made a complete precipitation of the antibiotics in culture broth. When treated with protease K and trypsase, the activities of antibiotics were decreased by 79% and 53%, respectively, compared with control. The antibiotics were sensitive to high temperature and were alkaline stable. The molecular weights of the substances were about 500-1000 Da. The bio-control efficiencies of the antibiotics had no significant difference with that of N43 cell suspension. It is a first report that B. pumilus strain produced oligopeptides which had inhibitory effect on R. solani Q1 at logarithmic growth phase.
authors: Jiangsu Key Laboratory for Organic Solid Waste Utilization, Nanjing Agricultural University, Nanjing, China.
authors: Xinqi
authors: X
authors: Huang
authors: Xiaoyu
authors: X
authors: Yong
authors: Ruifu
authors: R
authors: Zhang
authors: Qirong
authors: Q
authors: Shen
authors: Xingming
authors: X
authors: Yang
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D000935:Antifungal Agents / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D001407:Bacillus / Q000254:growth & development / Q000378:metabolism*; D018553:Cucumis sativus / Q000382:microbiology; D017077:Culture Media, Conditioned / Q000494:pharmacology; D019286:Endopeptidase K / Q000737:chemistry; D008970:Molecular Weight; D025282:Mycelium / Q000187:drug effects; D010935:Plant Diseases / Q000382:microbiology; D012232:Rhizoctonia / Q000187:drug effects*; D014617:Vacuoles / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D017077:Culture Media, Conditioned; D019286:Endopeptidase K
keywords: Antibiotic compounds; Bacillus; Oligopeptide; Rhizoctonia solani