Identification of 2-methylbutyric Acid as a Nematicidal Metabolite, and Biocontrol and Biofertilization Potentials of Bacillus pumilus L1

Abstract

The present study described the isolation of 2-methylbutyric acid (2-MBA) produced from Bacillus pumilus L1, to subsequently investigate its nematicidal activity for the control of the root-knot nematode. The results showed that 2-MBA could be purified by chromatographic techniques and was identified using nuclear magnetic resonance and liquid chromatography-mass spectrometry. Crude extract and partially purified compounds had a significant effect on the inhibition of egg hatchability and second-stage juvenile (J2) mortality. A dose-dependent effect of 2-MBA was observed for J2 mortality and egg hatchability. Egg hatchability was 69.2%, 59.9%, 32.7%, and 0.0% at 125, 250, 500, and 1000 μg mL -1 of 2-MBA after 4 d of incubation, respectively. Meanwhile, J2 mortality was in the range of 24.4%-100.0% after 2 d of incubation, depending on the concentrations of 2-MBA used. A pot experiment also demonstrated that treatment of B. pumilus L1 culture caused a significant reduction in the number of galls, egg masses, and J2 population than that of the tap water (TW) control. However, as the B. pumilus L1 culture concentration was decreased, the efficacy of nematode control by treatment of B. pumilus L1 culture was reduced compared to that of TW. B. pumilus L1 inoculation at different concentrations also promoted cucumber plant growth. Therefore, our study demonstrated the potential of 2-MBA from B. pumilus L1 as a biocontrol agent against the root-knot nematode and a plant growth promoter for cucumber plants.

Impact of Bacillus subtilis, Trichoderma spp. and The Bioproduct Top Perfect on Meloidogyne incognita Infecting Pepper Plants

“…as biocontrol agents are promising, but their activity should be evaluated under field conditions. Lee et al (2016) reported that B. subtilis produced both protease and chitinase enzymes, which were the main causes for its root-knot nematode antagonistic characteristics.…”

Natural nematicidal metabolites and advances in their biocontrol capacity on plant parasitic nematodes

“…65 2-Methylbutyric acid (2-MBA) 145 was produced from Bacillus pumilus and was found to exhibit a dose-dependent effect on J2 mortality and egg-hatching ability for Meloidogyne arenaria . 66 …”

Effect of cultivation media and temperature on metabolite profiles of three nematicidal Bacillus species

“…This is an important precursor step for higherlevel identification (molecular formula and confirmed structure) (Schymanski et al, 2014), and relates to the main goal of metabolomics which is to identify a few unique chemical features that define a biological system (Worley & Powers, 2013). Higher-level identification has been achieved for some Bacillus nematicidal metabolites, including styrene produced by B. mycoides (Luo et al, 2018), 2-methylbutyric acid by B. pumilus L1 (Lee et al, 2016), uracil by B. cereus and B. subtilis, and dihydrouracil and 9H-purine by B. subtilis (Oliveira et al, 2014).…”