Isolation and characterization of polyketide drug molecule from Streptomyces species with antimicrobial activity against clinical pathogens.
Natural products derived from marine microbes have more potential toward to treatment of various diseases. Among the microbes, the secondary metabolites recovered from the marine actinomycetes were more added values.
A promising antimicrobial metabolite producing filamentous actinomycete SCA-7 recovered from Alkhobar marine region was investigated for its potential to inhibit Gram positive Enterococcus sp. In addition to the chemical characterization, the polyketide gene cluster of the actinomycete SCA-7 was sequenced.
Among the 8 actinomycetes isolated from the marine sample, the isolate SCA-7 produced significant antimicrobial activity against Enterococcus sp. The biochemical, physiological and morphological characteristics and fermentation assimilation pattern confirmed that the isolate belonged to the genus Streptomyces. The 16S rRNA gene amplification and sequencing results showed 99% sequence similarity to Streptomyces felleus. The antimicrobial activity of the crude ethyl acetate extract was performed by disc diffusion method. The spectral characterization was done by 13C NMR and 1H NMR. The compound was polyketide in nature. The Minimum Inhibitory Concentration (MIC) of the polyketide compound against Enterococcus sp. was 25μg/mL. Among the agro-industrial waste materials, wheat bran showed increased secondary metabolite production. Antibacterial activity was found to be high when the isolate SCA-7 was grown in wheat bran substrate and maximum zone of inhibition (22mm) was recorded in it. Among the carbon and nitrogen sources, lactose enhanced the production of secondary metabolites and the zone of inhibition against Enterococcus sp. was 25mm. The amplification and sequencing of the ketoacyl synthase gene clearly indicated that it was type I polyketide synthase (PKS) gene of Streptomyces species.
Overall, the therapeutic drug molecule isolated from the marine Streptomyces species might be used for the treatment of disease causing microbial clinical pathogen.
Almalki MA
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Four new polyketides from an endophytic fungus Talaromyces muroii.
In our continuous work on the isolation of endophytes, the endophytic fungal strain YIMF00209 was obtained from the roots of Gmelina arborea, which is an ethnic medicinal plant mainly distributed in Southeast Asia. The fermentation extracts of the strain exhibited significant antimicrobial activities against Staphylococcus aureus, Fusarium solani, and Escherichia coli. Based on morphological characteristics and phylogenetic analysis, it was identified as Talaromyces muroii. Four new polyketides, talaromurolides A-D (1-4), along with 26 known compounds (5-30), were isolated from the culture broth of the strain in two different media. Their structures were identified based on HRESIMS, NMR, and CD spectral data. Among them, compounds 2, 4-6, 19, 22, 24, 27, 28, and 30 were isolated from the fermentation broth in CYM medium; compounds 1, 3, 7-18, 20, 21, 23, 25, 26, and 29 were obtained from the fermentation broth in PDB medium; and compounds 2, 5, and 30 were existed in both two media. Compounds 6-9, 12, 16, 20, 21, 23, 25, and 29 were obtained from the genus Talaromyces for the first time. The antimicrobial activities of several compounds were assayed against six pathogens. Compound 1 exhibited inhibitory activities against S. aureus, E. coli, Candida albicans, Salmonella typhimurium, and Botrytis cinerea with MIC value of 64 μg/mL. Compound 25 exhibited antibacterial activity against E. coli with MIC value of 32 μg/mL.
Zhu S
，Xu TC
，Huang R
，Gao Y
，Wu SH
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ResearchGate
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钛学术
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