Screening Of Soil Actinomycetes For Antibacterial Activity

As a kind of microorganism that can make fruitful bioactive substances, actinomycetes has been a hot research field of bio-pesticides. The human has been successfully developed avermectins , spinosad and validamycin which have widely used in agriculture. In my study, 94 strains actinomycete were screened for antibacterial activity and the activity strains were systematically studied for antibacterial activity and taxonomic status. The main results were as follows:1. Anagonistic function of 94 strains actinomycete on S.sclerotiorum,B.cinerea,F.fulva was studied. The result showed that 10 strains of which have better antagonistic action against three pathogens, and the inhibition rates were more than 60%. The results of spore germentation test showed that the inhabition rate of strain AXW4-1 and strain HVA29-2 were 86.9% and 78.8% to B.cinerea respectively, and strain X-1-8 and strain GSA26-2 were 100% to germentation of sclerotia. The test of leaves of oilseed rape showed that the filtrate of strain X-1-8 and strain GSA26-2 have more than 90% efficacy to S.sclerotiorum. The antibacterial activity of the filtrate of 94 strains actinomycete were tested to B.cinerea on tomato fruits and the result showed that no activity strain be found.2. Systematically studied the antibacterial activity of strain X-1-8 and strain GSA26-2, and the result showed that they have significant and stable activity to S.sclerotiorum: The results of sclerotia germentation test showed that the inhabition rate of strain X-1-8 and strain GSA26-2 were 46.5% and 39.5% to germentation of sclerotia respectively when the filtrate was diluted 100 times; The test of leaves of oilseed rape showed that the strain X-1-8 has 86.6% efficacy to S.sclerotiorum when the filtrate was diluted 10 times; The results of pot test showed that the filtrate of strain X-1-8 and strain GSA26-2 have 95.6% and 100% efficacy to S.sclerotiorum. The filtrate of strain X-1-8 and strain GSA26-2 also have more than 85% protective and therapeutic efficacy to B.graminis. The ethanol extract of strains and filtrate of strain X-1-8 and strain GSA26-2 were tested to all 13 kinds of pathogenic fungi, the result showed that they all have significant inhibition effect to R.cerealis. The ethanol extract of strains and filtrate of strain X-1-8 have 88.4% and 100% inhabition rate respectively to R.cerealis; The ethanol extract of strains and filtrate of strain GSA26-2 have 90.8% and 90.5% inhabition rate respectively to R.cerealis.3. Based on the phenotypic information and the Sequence of 16SrRNA , the train X-1-8 was inentified as Streptomyces aureus. Based on the morphology, culture, physiological and biochemical characteristics, the strain GSA26-2 was preliminarily identified as Streptomyces sp.