Preliminary Study On Solid - State Fermentation And Bacteria Of Streptomyces Sp

In recent years, jujube black spot restricts the development of jujube industry. Jujube black spot is a fungal disease that seriously affects the yield and quality of jujube fruit. The black spot is caused by Alternaria tenuissima. Chemical control is not conducive to ecological sustainable development and the prevention of agricultural cultivation is easy to be restricted by environment. These prompt people to continue to explore biological control. For example, we can separate the antibiotics or produce biocontrol agent. Antagonistic streptomyces K14 was selected from rhizosphere soil of Zhanhua jujube cultivation area, which had a strong antagonist to Alternaria tenuissima under laboratory conditions. This paper aims to provide reference for the biocontrol agents of jujube black spot. The main results are as follows:1. In order to make the spore powder preparation, we conducted experiments in solid state fermentation. Using brown rice, maize flour, soybean powder, crushed straw, wheat bran, the optimum sporulation combination was A1B3C3D3. Brown rice and inorganic salt solution ratio was 1:1.3, brown rice and soybean powder percentage was 15%, brown rice and corn flour percentage was 30%, brown rice and wheat bran percentage was 15%. At 30℃, initial pH 7.4,inoculation amount 6%, and bottled volume 100 g, the maximum sporulation quantity was37×108cfu/g.2. With kaolin and flour as the carrier, they were not found inhibition of cell growth. We have applied to the agents leads to decrease the incidence of jujube. Incidence of disease decreased from 90% to 31.7%.3. The original strain of Streptomyces K14 was treated by microwave and LiCl concentration gradient mutagenesis. Prescreening and screening again after mutagenesis. The mutant strains were preserved.4. In postharvest jujube fruits as raw materials, found that spore suspension, culture liquid,aseptic filtrate, cell lysates, and sterilization fermentation liquid of antagonistic Streptomyces K14 can reduce the incidence rate of jujube black spot.