Soluble macromolecules from two Streptomyces strains with potent nematicidal activity against Meloidogyne incognita

Abstract

Actinobacteria, which produce nematicidal metabolites, have been reported wildly. However, macromolecules were rarely described. The culture filtrates of Streptomyces albogriseolus ND41 and S. fimicarius D153 presented 82.13% and 86.96% nematicidal activity against Meloidogyne incognita after 12 h, respectively. A pot experiment highlighted that the biocontrol efficiency of strain ND41 reached 68.89% and that of strain D153 74.44% after 30 days at a dose of 100 mL per pot. The active metabolites produced by the two strains were hydrosoluble, with molecular weights above 8000 Da for ND41 and of 1000–8000 Da for D153. A chemical characteristic test indicated that these active metabolites were polar polymers that contained a large amount of sugar and phenolic hydroxyl compounds. The insoluble property of most nematicidal pesticide limits dosage form and range of application. Nematicidal metabolites from S. albogriseolus ND41 and S. fimicarius D153 would be preferred candidates for the control of root-knot nematodes, as hydrosoluble macromolecules have good compatibility to soil and root, and are convenient for practical application.