Endophytic Streptomyces sp. NEAU-DD186 from Moss with Broad-Spectrum Antimicrobial Activity: Biocontrol Potential Against Soilborne Diseases and Bioactive Components

Soilborne diseases cause significant economic losses in agricultural production around the world. They are difficult to control because a host plant is invaded by multiple pathogens, and chemical control often does not work well. In this study, we isolated and identified an endophytic sp. NEAU-DD186 from moss, which showed broad-spectrum antifungal activity against 17 soilborne phytopathogenic fungi, with being the most prominent. The strain also exhibited strong antibacterial activity against soilborne phytopathogenic bacteria . To evaluate its biocontrol potential, the strain was prepared into biofertilizer by solid-state fermentation. Response surface methodology was employed to optimize the fermentation conditions for maximizing spore production and revealed that the 1:1 ratio of vermicompost to wheat bran, a temperature of 28°C, and 50% water content with an inoculation amount of 15% represented the optimal parameters. Pot experiments showed that the application of biofertilizer with a spore concentration of 10 CFU/g soil could effectively suppress the occurrence of tomato bacterial wilt caused by and wheat root rot caused by , and the biocontrol efficacy was 81.2 and 72.2%, respectively. Chemical analysis of strain NEAU-DD186 extracts using nuclear magnetic resonance spectrometry and mass analysis indicated that 25-O-malonylguanidylfungin A and 23-O-malonylguanidylfungin A were the main active constituents, which showed high activity against (EC of 2.46 and 2.58 µg ml ) and (EC of 3.92 and 3.95 µg ml ). In conclusion, this study demonstrates that sp. NEAU-DD186 can be developed as biofertilizer to control soilborne diseases.