Nematicidal spore-forming Bacilli share similar virulence factors and mechanisms

Abstract

In the soil environment, Bacilli can affect nematode development, fecundity and survival. However, although many Bacillus species can kill nematodes, the virulence mechanisms Bacilli utilize remain unknown. In this study, we collected 120 strains comprising 30 species across the Bacillaceae and Paenibacillaceae families of the Bacillales order and measured their nematicidal activities in vitro. Comparison of these strains’ nematicidal capacities revealed that nine species, including Bacillus thuringiensis, B. cereus, B. subtilis, B. pumilus, B. firmus, B. toyonensis, Lysinibacillus sphaericus, Brevibacillus laterosporus and B. brevis, were highly nematicidal, the first of which showed the highest activity. Genome sequencing and analysis identified many potential virulence factors, which grouped into five types. At least four possible mechanisms were deduced on the basis of the combination of these factors and the bacterial nematicidal activity, including a pore-forming mechanism of crystal proteins, an inhibition-like mechanism of thuringiensin and a degradation mechanism of proteases and/or chitinases. Our results demonstrate that 120 spore-forming Bacilli across different families share virulence factors that may contribute to their nematicidal capacity.

Genetic and Biochemical Characterization of a Gene Operon for trans-Aconitic Acid, a Novel Nematicide from Bacillus thuringiensis

“…Recent, research has classified B. thuringiensis as a bacterial pathogen of alternative nematode hosts (2)(3)(4), which may help to explain the complex ecology of B. thuringiensis that was previously thought to have a sole insect host (2,5,6). This finding further contextualizes already established interactions between B. thuringiensis and nematodes (1)(2)(3)(4)7), including free-living and parasitic species. The relationship between nematodes and B. thuringiensis is of great importance, because it not only gives new insights into the evolution and ecology of this important environmental microorganism (2, 3, 7) but also provides promising resources or strategies for nematode management.…”

Bacillus thuringiensis targets the host intestinal epithelial junctions for successful infection of Caenorhabditis elegans

“…In this work, we analysed the pathogenicity in C. elegans of six nematicidal wild‐type Bt strains (YBT‐1518, C15, G25‐41, G25‐46, G25‐51 and G25‐53) (Zheng et al ., ; Peng et al ., ) and one recombinant Bt strain (BMB0215) (Guo et al ., ) (Supporting Information Table S1). As negative controls we used a non‐nematicidal Bt strain YBT‐1520 (Zhu et al ., ), and an acrystalliferous mutant of Bt strain BMB171 (He et al ., ) (Supporting Information Table S1).…”

Alternative products for Pratylenchus brachyurus and Meloidogyne javanica management in soya bean plants

“…The fungus Trichoderma spp., as well as bacterial species belonging to genus Bacillus spp., stands out among the large-scale-use biological control agents with potential to successfully control nematodes. These agents present multiple action forms against the main nematode genera, namely: the production of substances able to affect the nematode metabolism or to change the rhizosphere composition, the ability to colonize the surface of the root system by competing with the nematode for penetration sites, as well as the ability to stimulate plant development or to activate the plants' defence mechanisms (Adam, Heuer, & Hallmann, 2014;Harman, Howell, Viterbo, Chet, & Lorito, 2004;Lian et al, 2007;Ludwig, Moura, & Gomes, 2013;Oliveira et al, 2014;Sharon, Chet, & Spiegel, 2011;Sharon, Chet, & Viterbo, 2007;Yu et al, 2015;Zheng, Zhenf, Zhang, Peng, & Sun, 2016).…”