Improving suppressive activity of compost on phytopathogenic microbes by inoculation of antagonistic microorganisms for secondary fermentation

Antimicrobial activity contributes to plant disease control property of composts but its source is still not clear. From composting cow manure during secondary fermentation, 50 microbial strains with antifungal activity were isolated and identified. Two bacterial strains Bacillus mojavensis B282 and Pseudomonas aeruginosa F288, antagonistic against both phytopathogenic fungi and bacteria, were respectively used as the inoculum of compost for secondary fermentation. Inoculation of B282 or F288 significantly shifted microbial community structure of compost and genera functionally linked to antagonistic activity and plant growth promotion were enriched. Notably, culturable cells of B282 increased by about 40 times during secondary fermentation. The inoculation of each strain significantly increased antifungal activity of compost extracts and enhanced disease suppressive ef-fects of compost on wheat root rot. This study demonstrates that inoculation of compost-indigenous microor-ganisms could improve antimicrobial activity of compost and provides a low-cost strategy for producing bio-organic fertilizers with biocontrol function.

Automated summary

Fifty microbial strains with antifungal activity were isolated and identified from composting cow manure. Two bacterial strains, B282 and F288, were found to be antagonistic against both phytopathogenic fungi and bacteria. Inoculation of these strains significantly changed the microbial community structure of compost and increased the antimicrobial activity and disease suppressive effects of compost.