[Phylogenetic diversity characteristics of soil bacteria producing nematode-attracting volatiles and identification of their active compounds]

This study characterized the phylogenetic diversity of soil bacteria producing nematode-attracting volatiles and their nematode-attracting compounds. Results would enhance our understanding on the interaction between nematodes and soil microorganisms and potentially enhance the biocontrol efficiency when combined the attractants with nemacides.

Bacteria producing volatiles with functions of nematode-attracting activities were isolated from 187 agricultural soil samples collected in 26 provinces of China with the method of double-Petri dishes. The phylogenetic diversity of these bacteria was characterized by RFLP-16S rRNA gene sequence analysis. The nematode-attracting volatiles of bacteria were detected using the SPME-GC/MS, and volatile compounds with attractive activity were determined by confirming with individual commercial compounds.

Among the 3800 bacteria isolated from the 187 soil samples, 196 isolates(5.16% of the total) showed attractive activity (AN)more than 30% to Panagrellus redivivus. Of the 196 isolates, 66 (1.74%) showed AN > or = 70%, 62 isolates (1.63%) showed AN between 50% and 70%, and 68 isolates (1.79%) showed AN less than 50%. Phylogenetic analysis revealed that the 196 bacteria were clustered into 5 groups: Bacilli, Gammaproteobacteria, Alphaproteobacteria, Sphingobacteria and Actinobacteria. But, Bacillus were the dominant, which covered 13 species. And 11 volatiles with nematode-attracting activity were determined, including benzaldehyde, 2-heptanone, benzyl benzoate, ethyl palmitate, (+)-longifolene, benzyl alcohol, p-anisaldehyde, vanatone, ethyl butyrate, isovanilin and d-alaninol.

Some species of bacteria in agriculture soil can produce volatiles to attract nematodes.