Nematicidal effect of rhizobacteria on plant-parasitic nematodes associated with vineyards

Abstract

The action of metabolites and exoenzymes from rhizobacteria on different plant-parasitic nematodes has an influence on the nematicidal efficacy of the microbe. Seven rhizobacteria, divided into two bacterial groups, were evaluated in vitro for nematicidal activity on Meloidogyne ethiopica and Xiphinema index. The direct effect of their filtrates on egg hatching and juveniles of M. ethiopica as well as mobile stages of X. index was evaluated during a 72-h period. The production of four exoenzymes and two metabolites associated with nematode mortality was investigated. Molecular characterization of three isolates was performed, and the physiological profiles and lipase activity of all isolates were obtained using the BIOLOG EcoPlate system. While chitinase and collagenase were measured using the BIOLOG MT2 plate system, protease, hydrogen cyanide and hydrogen sulphide were directly determined in Petri dishes. Nematode mobile stages exposure to the bacterial filtrate revealed a nematicidal effect up to 93.7% on X. Index and up to 83.3% on M. ethiopica. The control of egg hatching varied between 35 and 85%. A positive correlation was found between the mortality of both nematode mobile stages and the concerted activities of the bacterial enzymes as well as the level of the volatile metabolites. The nematicidal effect of rhizobacteria strains varies by nematode genera and among the developmental stages evaluated.

Screening, identification and application of soil bacteria with nematicidal activity against root‐knot nematode (Meloidogyne incognita) on tomato

“…B. mycoides killed M. ethiopica and inhibited the reproduction of this nematode . Studies have shown that B. weihenstephanensis , B. amyloliquefaciens and B. megaterium can kill nematodes; the mortality of Xiphinema index and M. ethiopica reached 93.7% and 83.3%, respectively . Additionally, Paenibacillus polymyxa , B. megaterium and B. circulans are common plant‐growth‐promoting bacteria (PGPB), which are used as biofertilizers to promote plant growth .…”

Intergrated Metagenomics and Metabolomics Analysis Discovers Nematicidal Microbes, Enzymes and Metabolites From the Plant Rhizosphere Microbiota

“…Microorganisms can kill nematodes by producing extracellular enzymes, including serine protease, metalloproteinase, collagenase, lipase and chitinase, which can degrade the nematode cuticle and eggshell [80,81]. We found the genes of chitinase, collagenase, lipase and protease were significantly overrepresented in the NS microbiota comparing with the RNI microbiota.…”

The carB Gene of Escherichia coli BL21(DE3) is Associated with Nematicidal Activity against the Root-Knot Nematode Meloidogyne javanica

“…The findings suggest that the nematicidal active components are present in supernatants of these isolates. Indeed, some bioactive substances, such as lytic enzymes, Cry toxins, 2-hydroxypropanoic acid, plantazolicin, 2, 4-DAPG and sphingosine isolated from bacterial culture filtrates, are well known to antagonize plant-parasitic nematodes [11,15,[32][33][34]. Analysis of BL21(DE3) culture filtrates indicated that the bioactive compounds were non-proteinaceous, heat and cold resistant and volatile, similar to the active components produced by B. subtilis strain OKB105 [29].…”