| In production agriculture of rice, Fungal pathogen of Magnaporthegriseainfects plants and crops easily and often seriously, causing millions of dollars worthof economic damage each year. So, how to control this disease and maintain thenormal growth of rice is always the highlight. Application of chemical pesticides isthe effective measure to control the fungal and bacterial infection and plays animportant role in preventive defence. With the further knowledge to chemicalpesticides, however, many concerns, such as the pollution of soil, water andatmosphere, the increase of the leftover of germicides in produce which imperilshuman health and life directly, ecological environment resulting from thepesticides, phytopathogenic fungi and bacteria to germicides, the agriculturalunbalance of and resistance of have caused the withdrawal of many of them. So,new and safe alternative control measures are much sought after. Biologicalcontrol by natural antagonistic organisms is a potential nonchemical tool for cropprotection against phytopathogenic fungi and bacteria and offers a promising alternative to synthetic pesticides, in part because it is perceived as safe to theenvironment and human health and can avoid the appearance of drug-resistance.Protoplast fusion is in the level of cell, which can breed industrial bacterium.lots of heredity message are transferred by Protoplast fusion. It does not need toknow the heredity background of candidacy bacteriums. There is an aim to getpotential industrial bacterium.Agricultural antibiotic 120, being from streptomyces hygrospinosusvar. beijingensis is often used to control the fungal and bacterial infection in plantand flowers. Streptomyce lavendule is also an impotant bacterium which produceantibiotic 751. By the method of protoplast fusion, two kinds of streptomyces canbe fused to get a new streptomyce which is used to restrain Fungal pathogen ofMagnaporthegrisea efficiently.Conditions about protoplast optimum preparation of S. hygrospinousvar. Beijingensis and S. lavendule were studied by orthogonal test, including theconditions of concentration of Gly, lytic temperature, lysozyme concentration andlytic time. Experimental results indicated that the conditions of optimum preparationof S. hygrospinous var. Beijingensis are as following: gly 0.5%, lytic temperature28℃, lysozyme 3 mg/ml, lytic time 60 min. Those of S. lavendule are as following:gly 1.0%, lyric temperature 32℃, lysozyme 4mg/ml, lytic time 60 min. Theregenerated frequency of protoplasts could reach up to above 15% in the conditionsof -20℃, 5 days.The MIC of S. hygrospinosus was about 33μg/mL(streptomycin). The minimumUV lethal time of S. lavendule' protoplast was about 60S. Two kings of protoplastswere fused by 40% PEG. There were 381 colonies in the culture medium platescontaining streptomycin 33μg/mL. The regenerated rate was about 1.0*10-2%. 50colonies were selected randomly and planted in the basic mediums and selectedones according to the methodology of natural isolation. There were 15heterocaryons, 30%. The stable haploid fusions was about 15% against Magnaporthegrisea remarkably. RH103, it was as 200% as S. hygrospinosus against Magnaporthe grisea remarkably.The physicochemical characteristics of the recombinant RH103 screened fromregenerated strains of fusiants between producing strains S. hygrospinosus andS. lavendule were studied. Through analysis the cultural characteristics of therecombinants in different medium in the process of culture, components andinhibition of its fermentation liquor to yeasts, the results showed that therecombinant RH103 is similarto the S. hygrospinosus. There are also differentfrom the original strains. Its mycelia are white color and produce little spores.
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