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Antifungal and plant growth-promoting activities of Streptomyces roseoflavus strain NKZ-259

Shi, Liming, Nwet, Thinn Thinn, Ge, Beibei, Zhao, Wenjun, Liu, Binghua, Cui, Hailan, Zhang, Kecheng
Biological control 2018 v.125 pp. 57-64
Streptomyces roseoflavus, beneficial microorganisms, biofertilizers, biological control, biological control agents, culture media, disease control, field experimentation, fungi, fungicides, gray mold, greenhouse experimentation, growth promotion, indole acetic acid, pathogens, pepper, plant height, seedlings, sequence analysis, soil sampling, tomatoes, China
Biocontrol approach, using beneficial microorganisms, is becoming an important alternative to the use of chemical fungicides to control crop diseases. Therefore there is a need to found new effective biocontrol agents. Herein, a bacterial strain named NKZ-259 was isolated from soil samples obtained from Qilian Mountain, Qinghai, using the dilution plate method and streak plate technique. Strain NKZ-259 was identified as Streptomyces roseoflavus based on 16S rDNA sequencing, which displayed high antagonistic activity against six fungal pathogens tested. A greenhouse experiment showed that the use of NKZ-259 fermentation broth reduced the incidence of the tomato gray mold by 66.67%, and promoted the growth of tomato and pepper seedlings, with a significant increase in plant height, root length, and fresh weight compared to controls; the field experiment also showed the growth promotion of tomato and pepper seedlings by the use of NKZ-259 fermentation broth. Furthermore, indoleacetic acid (IAA) production was also detected in strain NKZ-259 using the Salkowski’s reagent method, and was important for its plant growth-promoting effects. The results suggest that NKZ-259 has potential for commercial application as a biofertilizer or biocontrol agent.