Isolation And Identification Of Actinomycetes From Marine Shrimp Shells And Their Antifungal Extraction

The paper was undertaken to isolate actinomycetes from shrimp shell and to screen actinomycetes producing chitinase and protease , finally, two strains of actinomycetes T0907-15 and T0907-107 with antagonism were screened from the isolated actinomycetes ,and were initially identified. And then the paper was studying on the antimicrobial properties , the optimal medium compositions and cultural conditions, and the extraction of antifungal active substance of antagonistic strain T0907-107. The main results were as follows:1.By means of pretreatment and diluting plate method to shrimp shells, actinomycetes were isolated from shrimp shells. According to the color of the substrate mycelium , aerial mycelium ,and soluble pigment, the actinomycetes were initially identified. After excluding the repeat strains and newly registering, the result showed that 167 srains of actinomycetes were isolated from shrimp shells.2.By means of transparent cycle plates assay method, actinomycetes producing chitinase and protease were screened from strains of actinomycetes isolated from shrimp shells, and by preliminary screening of confront culture in plates and subsequent screening done under fermentation conditions, two strains of actinomycetes T0907-15 and T0907-107 with antagonism were screened from the isolated actinomycetes , presented very important antifungal activity against most of the filamentous fungi tested. According to the morphology , cultural characteristics , physiological and biochemical characteristics and 16S rDNA, the strain T0907-15 was indentified as Streptomyces lavendulae streptinus, and the strain T0907-107 was initially identified as Streptomyces luteoverticillatus that was difficult to isolate from the soil.3.For the seperation and determination of antifungal substance produced by antagonistic actinomycete T0907-107 , the result showed that it's a kind of good-keeping, nonprotein, medium-polar substance, which was stable at 60℃for 90 min, could resistant acid and alkali on pH 2 ~11, and was also stable after the treatment with natural light for 20 h and ultraviolet light for 60 min, presented very important antifungal activity against most of the filamentous fungi tested with wide antimicrobial spectrum.4.According to the single-factor and orthogonal experiments, the optimum fermentation medium and culture conditions were determined through flask liquid fermentation from which were suitable for antagonistic actinomycete T0907-107 . It was found that the most suitable fermentation medium were sucrose 1.0 %, soybean meal 1.0 %, and the most suitable culture conditions were initial pH value 7.0, the temperature of 30℃, incubation time from 84 h to 156 h , 2 % inoculum concentration(v/v), and 200 ~250 mL medium in 500 mL shake-flask.5.According to the principle of similar phase dissolve, and combining biological activity determination of active material and method of ultraviolet spectrophotometery, the test optimized the extracting process of antagonist actinomyces T0907-107 mycelial collected from liquid fermentation. And using the solvent extraction, preliminary explored a suitable preparation method of the condensate which included the antifungal active substance produced by antagonist actinomyces T0907-107.