Isolation and identification of a Streptomyces diastatochromogenes strain with biocontrol potential against Colletotrichum camelliae and Fusarium solani

Abstract:

[Background] Actinomycetes are a kinds of important biocontrol bacteria with strong metabolic activity, which can produce natural products such as antibiotics, enzymes, enzyme inhibitors, and hormones to inhibit the growth of pathogens. [Objective] To study the activities of the actinomycetes isolated from the rhizosphere soil of tea plants against Colletotrichum camelliae (pathogen of tea anthracnose) and Fusarium solani (pathogen of konjac stem rot) and evaluate the biocontrol potential of the isolates.[Methods] The antagonistic actinomycetes strains against C. camelliae and F. solani were isolated and screened from the rhizosphere soil of tea plants the plate dilution method, plate confrontation method, and mycelial growth assay. The isolates were identified based on the morphological characteristics, physiological and biochemical properties, and phylogenetic relationship. Furthermore, the abilities of actinomycetes to produce growth-promoting substances and secrete cell wall hydrolase were determined. [Results] A total of 14 actinomycete strains were isolated. Among them, the isolate A-dyzsc04-2, identified as Streptomyces diastatochromogenes, presented the inhibition rates of 66.71%±1.23% and 71.59%±2.46% against C. camelliae and F. solani, respectively. The 10-fold dilution of the cell-free fermentation filtrate of this strain presented the inhibition rates over 90% against the two pathogens. In addition, A-dyzsc04-2 was capable of producing siderophore and glucanase and dissolving inorganic phosphorus. [Conclusion] A-dyzsc04-2 serves as an elite biocontrol strain with a high development and utilization value. The results provide theoretical support for the application of A-dyzsc04-2 in the prevention and treatment of tea anthracnose and konjac stem rot.