| Plant virus disease is one of the most important diseases of crops and causes serious economic losses. Chemical pesticides are less effective in control of plant virus disease and have negative impacts to the ecological environment, quality of life for people and livestock. On the other hand it is not very easy to commercialization for botany-derived pesticides because of limited resources, high costs and instability. Therefore, it becomes a hot research field to screen and develop antiviral activity from microbe for controlling plant virus disease.Actinomycetes is a kind of microorganism which is very important to human beings. They exist in various kinds of natural environments. They can produce many kinds of active products including antibiotics and non-antibiotics for controlling disease caused by bacteria, fungi, viruses, parasitic nematodes and tumour. Streptomyces is the major to producer of second metabolite and 90% antibiotics are produced by Streptomyces in Actinomycetes. Streptomycin so far, many kind of antibiotics with various types and medicinally value such as erramycin, aureomycin, chloramphenicol have been fouynd. However antibiotics were rarely used in agriculture, especially for plant virus .In this study, research was carried out on following aspects:isolation of actinomycete, screening of antiviral strains and identification, optimizing fermentation condition and medium formulation, analysis, of active compounds.1) In order to improve the efficiency of isolation of actinomycetes from soil and solve the problem of contamination by fungi and bacteria when actionmycetes isolated and cultivated, several culture media and inhibitors was employed. The results showed that soil samples pretreated with 90℃1h, mixed with 0.05% SDS (5mmol/L phosphate buffer) for 20min, and cultured by dilute and spread plate methods on the Gause No. 1 medium containing K2Cr2O7 100mg/L were the best one for soil actinomycetes isolation. A total of 413 actinomycete isolates were separated from 117 soil samples in the study.2) An antiviral strain HNS2-2 was obtained by evaluated the control efficiency of culture filtrate in the system infection host Nicotiana tabacum cv. K326 and lesion host Datura metel of Tobacco Mosaic Virus (TMV) .3) By study on morphology, cultural characteristics, physiological and biochemical properties, 16SrDNA and phylogenetic tree, HNS2-2 was identified as Streptomyces. herbaricolor, The Genbank accession number for the 16S rDNA gene sequence of strain HNS2-2 is EU035296.4) The best optimal liquid fermentation and medium formulation was researched by effects of carbon source, nitrogen source, fermented temperature, pH value , inoculation amount, incubation volume, inoculation ages and fermention time. The research showed that the optimum culture medium consists of: rice powder 10%, soybean meal 2.2% and K2HPO4 1%, CaC030.4%. The optimum inoculation condition is: initial pH7. 0-7. 2, seed cultural time 24h, 8% inoculation amount, 30℃, 220r/min for 96h,5) Raw extract was obtained from the fermentation broth of HNS2-2 by pretreated of heated and acidification, evaporation and concentration, dialysis isolation, acetic ether extraction. The results showed that the activity of HNS2-2 is a small molecule compounds fat-soluble.
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