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Keywords
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Meloidogyne arenaria, Bacillus wiedmannii, Secretory proteins, Antagonism, Protease, Chitinase
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Abstract
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Background With increased environmental concerns and restrictions of chemical control, the importance of other
eco-friendly strategies for management of the nematodes is being substantially grown nowadays. One of the most
well-known strategies that have attracted the attentions is biological control of these deleterious agents. In our previ‑
ous study (Moslehi et al. in Egypt J Biol Pest Control 31:1–11, 2021), Bacillus wiedmannii AzBw1 was introduced as a
robust antagonistic agent against root-knot nematode Meloidogyne arenaria. Present study addressed the possible
mechanisms of action of this strain.
Results Based on quantitative bioassays it was shown that the strain AzBw1 is able to produce considerable amount
of siderophore, protease, and chitinase. In an in vitro assay conducted by bi-plate Petri dishes, it was shown that
hatching of the nematode eggs, subjected to bacterial volatile compounds (BVCs) was 34% lower than those of
mock-treated control eggs. On the other hand, mortality of BVC-treated juveniles was 33.5% higher than those of
mock-treated control juveniles. The secretory proteins from the medium culture of strain AzBw1 were precipitated
and fractionated by anion exchange chromatography (AEC). Fractions from AEC were checked for hydrolytic activity
and nematicidal efect. It was found that the fractions with the highest protease activity have a strong nematicidal
efect. In contrast, signifcant nematicidal efect in the fraction with Chitinase activity was detected.
Conclusion The results suggested that protease activity played a key role in strain AzBw1 antagonism against rootknot nematode, M. arenaria. Finally, nonvolatile organic compounds were also extracted from the medium culture
after removing secretory proteins and enzymes. Obtained results showed that these metabolites had also a strong
anti-nematode efect.
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