Screening and identification of actinomycetes for biological control of Bursaphelenchus xylophilus and preliminary study on their toxicity factors

ObjectiveThis paper aims to screen and identify the actinomycetes with high killing activity against pine wood nematodes Bursaphelenchus xylophilus from soil, and determine their virulent factors.

MethodUsing Sarcina lutea, Bacillus subtilis and Escherichia coli as testing strains to determine the antibacterial activities, the actimomycetes with biocontrol activities to B. xylophilus were screened from the soil samples of Nanyang Normal University campus, Baihe Edge, Baotianman and other fields. Morphological observation and molecular identifications based on 16S rRNA sequence analysis were used to classify and identify the strain with the highest activities. The activity of the strain against pine wood nematode was tested, and the virulent substance was isolated and purified.

ResultFour actinomycete strains with antibacterial activity were screened: C611, C612, C614 and C619. The strain C611 showed the highest inhibitory activity against S. lutea, B. subtilis and E. coli among the four strains. The strain was identified as Streptomyces sp. according to the morphological and phylogenetic analysis. After 7 days of treatment of pine wood nematode with C611 fermentation broth, the mortality rate of nematode reached 85%, and that of blank control group was 0. The active ingredient was determined to be furan ketone (furaltadone) after separation and purification of C611 fermentation broth.The nematode mortality reached 96% after 5 days treated with 0.1% pure furatanone solution.

ConclusionThe actinomycete C611 was isolated and identified furaltadone as a key virulence factor in this study, which enriched the species of biological control microbe against pine wood nematodes. It was first reported that furantone had strong toxicity to nematodes and laid a theoretical foundation for biological control of pine wood nematode.