Novel chitinase producer Bacillus pumilus RST25 isolated from the shellfish processing industry revealed antifungal potential against phyto-pathogens

- Bacillus pumilus RST25 and strain SUK25 demonstrated hydrolysis of chitin within 72 h and 96 h.
- Physico-chemical optimization showed highest chitinase activities at pH 7.0, temperature 40 °C, and 1.0% (w/v) chitin.
- Plant pathogen Fusarium solani was inhibited through antagonism by B. pumilus RST25.
- B. pumilus RST25 chitinase showed in-vitro antifungal activities against Fusarium solani and Aspergillus niger.
- The chitinase was employed as seed dressing revealed suppression of the seed infections.

Biological control of plant pathogens using chitinolytic microorganisms and their derived chitinase is gaining much attention for its implementation in agriculture. In present study, based on hydrolysis zones on chitin agar two distinct strains RST25 and SUK25 were isolated from the shellfish processing industrial soil. Under the submerged conditions these strains RST25 and SUK25 produced maximum chitinase activities at 72 h (59.4 ± 1.1 U ml−1) and 96 h (51.7 ± 0.8 U ml−1), respectively. The free N-acetyl D-glucosamine (GlcNAc) and protein content in the chitin hydrolysis medium was analogous with the chitinase production. In addition, both chitinases demonstrated highest activities at pH 7.0, temperature 40 °C, and 1.0% (w/v) chitin substrate. The strain RST25 was found to be most potent chitinase producer which was further identified as Bacillus pumilus RST25 based on 16S rRNA sequence analysis. In dual culture technique, B. pumilus RST25 exhibited antagonism effect against plant pathogen Fusarium solani. The in-vitro assay for antifungal potential of crude and partially purified chitinase from strain RST25 showed significant inhibition of Fusarium solani and Aspergillus niger. Furthermore, the strain RST25 chitinase suppressed the fungal infections when applied for seed dressing to Triticum astivum. Hence, our results revealed the ability of B. pumilus RST25 and its produced chitinase as a possible biocontrol agent against fungal phyto-pathogens.

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