RESUMO
Genetic characterization of afsK-av (SAV3816) in Streptomyces avermitilis ATCC 31272 was performed to evaluate the role(s) of this eukaryotic-type serine-threonine protein kinase (STPK) in the regulation of morphologic differentiation and secondary metabolism. The afsK-av::neo mutant (SJW4001) was defective in sporulation, melanogenesis, and avermectin production. These phenotypic defects were complemented by introduction of either the intact afsK-av or the 900-nt catalytic domain region. The catalytic domain restored sporulation and melanogenesis to SJW4001 whereas it partially recovered avermectin production. This study reveals that AfsKav is a pleiotropic regulator and demonstrates in vivo that the C-region of AfsKav is not essential for its regulatory role in S. avermitilis differentiations.
Assuntos
Domínio Catalítico/genética , Proteínas Serina-Treonina Quinases/genética , Streptomyces/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Teste de Complementação Genética/métodos , Ivermectina/análogos & derivados , Ivermectina/metabolismo , Melaninas/metabolismo , Mutação/genética , Proteínas Serina-Treonina Quinases/metabolismo , Esporos Bacterianos/genética , Esporos Bacterianos/metabolismo , Streptomyces/enzimologia , Streptomyces/fisiologiaRESUMO
AIMS: To identify an antagonistic strain against Streptomyces scabiei and to characterize the antibiotic agent. The efficacy of the isolated strain in controlling common scab disease was also evaluated. METHODS AND RESULTS: A bacterial strain antagonistic against S. scabiei was isolated from the soil of a potato-cultivating area. This bacterium was identified as a Bacillus species by 16S rRNA gene sequence analysis and was designated Bacillus sp. sunhua. Antibiotics produced by this strain were proven to be stable within a broad pH range and at high temperatures. The culture broth was extracted with ethyl acetate, and then the crude extract was applied to HPLC. Two compounds were isolated and identified as iturin A and macrolactin A by 1H-NMR, 13C-NMR, HMBC, HMQC and mass spectrometer. The culture broth of Bacillus sp. sunhua had a suppressive effect on common scab disease in a pot assay, decreasing the infection rate from 75 to 35%. This strain also suppressed Fusarium oxysporum, the pathogen of potato dry rot disease. CONCLUSIONS: Bacillus sp. sunhua was shown to inhibit S. scabiei effectively. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report demonstrating that macrolactin A and iturin A inhibit S. scabiei. This study demonstrated the possibility of controlling potato scab disease using Bacillus sp. sunhua.
