Abstract: In this study, the endophytic actinomycetes in tomato plants in the farmlands in Huaibei City of Anhui Province were isolated and screened, and the bioactivities of the actinomycetes against pathogenic fungus Botrytis cinerea were determined. The population density of the actinomycete in the tomato roots, stems, and leaves were 5.66×10⁴, 0.67×10⁴, and 0.39×10⁴ CFU·g^-1 fresh weight, respectively. According to the isolation position and phenotype characteristics, a total of 93 endophytic actinomycete strains were isolated from different tissues of healthy tomato plants, and, by using dual culture technique, 7 strains with antagonistic activities against B. cinerea were screened, accounting for about 7.5% of the endophytic actinomycetes isolated. Among the 7 strains, the HNU-EA27 isolated from tomato roots had the best inhibition effect, with a formed inhibition zone of 28.3 mm. Based on the morphology, cultural characteristics, physiological and biochemical properties, chemotaxonomy, and 16S rDNA sequencing, the HNU-EA27 was identified as Streptomyces toxytricini.The culture filtrate of HNU-EA27 could inhibit the mycelium growth and spore germination of B. cinerea. The higher concentration the culture filtrate, the stronger the inhibition activity was. 30% culture filtrate of the HNU-EA27 could completely inhibit the mycelium growth and spore germination of B. cinerea. Pot experiment showed that the prevention efficiency and cure efficiency of 30% HNU-EA27 culture filtrate against tomato gray mould were 80.6% and 73.8%, respectively, being superior to those of the 600-fold dilution of 50% badistan. It was suggested that the strain HNU-EA27 could be valuable in the bio-control of tomato gray mould.

Key words: environmental problems, urban metabolism, prior modes, urban ecosystem.