Bacillus pumilus strain LYMC-3 shows nematicidal activity against Bursaphelenchus xylophilus via the production of a guanidine compound

Bacillus pumilus strain LYMC-3 was isolated from the stem of Pinus massoniana, and its culture filtrate exhibited strong nematicidal activity towards pinewood nematodes (Bursaphelenchus xylophilus). In this study, the nematicidal substance from the culture filtrate of B. pumilus LYMC-3 was isolated using a rotary evaporator, TLC (thin-layer chromatography), silica gel column chromatography, and HPLC. A single nematicidal compound was purified and identified as 2-{3-[(3S,8aS)-1,4-Dioxooctahydropyrrolo[1,2-a] pyrazin-3-yl] propyl}guanidine by LC-MS/MS. The median lethal concentrations (LC50) of the guanidine compound were determined as 113.5 mg L−1 and 62.5 mg L−1 against pinewood nematodes after 24 h and 48 h of treatment, respectively. This study demonstrates the nematicidal activity of the guanidine compound from B. pumilus LYMC-3, and highlights the high potential for the compound to be used in biocontrol of B. xylophilus.