SCREENING AND ANTIBACTERIAL ACTIVITY OF BIOCONTROL ACTINOMYCETES AGAINST BACTERIAL SOFT ROT IN PLANTS

At present, people pay attention to the development of ecological agriculture, and more and more scholars at home and abroad have begun to study biological control. The comprehensive promotion and application of biological control is beneficial to environmental protection, the input cost is low, and the control effect is remarkable. The ratio of actinomycetes in the rhizosphere of plants and soil is relatively large, and actinomycetes can produce biologically active compounds, which are also the most potential biocontrol factors. Rational use of secondary metabolites produced by actinomycetes, which is often referred to as antibiotics, is used as the main substance for the manufacture of pesticides. This pesticide is free of any pollution, can be regenerated, and will not lead to enhanced biological resistance, and can be industrialized. A large number of different types of microorganisms live in the plant rhizosphere soil. The main function of the plant root system is to produce a large amount of exudates. These exudates, as the main substances and nutrients of the microorganisms in the soil, will directly determine the structure of the rhizosphere microbial colony. Nowadays, technologies such as detection of products, isolation of bacterial species, and structural identification have developed rapidly, and the study of rhizosphere actinomycetes and antibacterial activity has become the dominant. The experimental method was combined with the dilution plate separation method to separate the vanilla orchid rhizosphere soil bacteria and actinomycetes. The results showed that the number of soil bacteria and soil actinomycetes in different media was different, and the medium with the largest number of strains was R2A, which had the highest number of strains. The strains with antibacterial activity in the rhizosphere soil were screened, and the diversity and antibacterial activity of actinomycetes were studied. It was concluded that G29 actinomycetes had broad-spectrum antibacterial activity. Based on its identification based on the 16S rRNA gene sequence method, the results showed that the G29 actinomycete strain was S. costaricanus. Except for the pH value of 5.0, it can be applied to various pH value environments and has strong antibacterial activity.