Efficacy evaluation of Streptomyces nigrescens KA-1 against the root-knot nematode Meloidogyne incognita

The nematicidal effects of Streptomyces nigrescens KA-1 isolated from soil samples of Mt. Naejang (Korea) were evaluated against Meloidogyne incognita in vitro and in vivo (pot experiments). The culture broth of the KA-1 strain exhibited 91.3% nematicidal activity in in vitro assays, and this strain significantly reduced the number of nematodes in the soil and the number of egg masses in roots of red pepper in in vivo pot experiments. In addition, anti-nematicidal substances were isolated from the culture broth of the strain and identified as trichostatin C (1) and dehydroxytrichostatin A (2) through various spectroscopic analyses (1H, 13C NMR and MS). These com-pounds showed potent anti-nematicidal activity against M. incognita. Therefore, the KA-1 strain, containing these active compounds, may be used as a biocontrol agent against M. incognita.