Studies On Antimicrobial Components From Fermentation Broth Of C-411bandc13Actino-Mycetes

This paper is about the research work based on two actinomycete strains C-411b andC13, including strain identification, evaluation of antimicrobial activity and purification ofthe main active metabolite.The main results are as follows:(1) Based on the results of cultural characteristics, physiological and biochemical meas-urement and analysis of16S rDNA sequence, strain C-411b was identified and designated asStreptomyces rishiriensis C-411b.Likewise, stain C13was identified and designated as Strep-tomyces albolongus C13.(2) Bioassay results in vitro showed that the fermentation broth of C-411b exhibitedstrong inhibitory against Bacillus subtilis,Bacillus cereus and Pseudomonas syingae,the anti-bacterial diameters were22mm,18mm and17mm,respectively. It also exhibited strong in-hibitory effect on mycelial growth against Botrytis cinerea, Colletotrichum gloeosporioides,Drupe colletotrichum gloeosporioiles, with the inhibition rate of95%,85%,85%,respectively.The protective effect was not apparent against Blumeria graminisThe fermentation broth of C13showed the inhibition with antibacterial diameter upto25mm against Pseudomonas syingae,15mm against Bacillus subtilis and17mm againstBacillus cereus.The inhibitions were not selective with the same inhibition rate of50%agai-nst eight pathogenic fungis.It had not protective effect against Blumeria graminis.(3) Guided by the results of the bioassay, compound Za-1was separated from the fer-mentation broth of C-411b by macroporous resin,silica gel column chromatography andPre-HPLC.According to analysis of ESI-MS and NMR spectroscopy,compound Za-1wasidentified as the ionophore X-206.Similarly,three compounds,C13-1,C13-2,C13-3,were iso-lated from the fermentation broth of C13and identified as SF2738F,SF2738D and SF2738Bbased on ESI-MS, NMR spectroscopy analysis,respectively.(4) The results of the antibacterial activity showed that the compound Za-1had strongantibacterial activity against Bacillus subtilis and Pseudomonas syingae with MIC values of0.78and6.25μg/mL,respectively.Za-1had no effect on mycelial growth against Fusariumgraminearum,but had different degrees inhibition against Alternaria alternate、Colletotrichumgloesporioides、Sclerotinia sclerotiorum, and inhibition rate were77.56%,88.99%,73.18%, respectively,under the1μg/piece.Compound C13-1showed strong antibacterial activity against Escherichia coil,Staphylococcus aureus with MIC values of0.313and0.625μg/mL,respectively.C13-2showed the better antibacterial activity against Pseudomonas syingae and Erwinia carotovorawith MIC values of10μg/mL.C13-3showed strong antibacterial activity against Pseudomo-nas syingae with MIC values of2.5μg/mL.In the concentration of the test,the compoundsC13-1~C13-3were not significantly inhibition to spores germination of the test pathogenicfungis.