EFFECT OF CULTURE CONDITIONS ON β-1,3-GLUCANASE PRODUCTION BY Paenibacillus polymyxa M6

In this study, we isolated and optimized the culture conditions for β-1,3-glucanase biosynthesis by a highly enzyme-producing bacterial strains isolated in Thua Thien Hue province. Among the three isolates M6, DH2, and T5, strain M6 exhibited the strongest β-1,3-glucanase production with the strongest hydrolysis zone of 19.03±0.05 mm diameter. Strain M6 was identified through nucleotide sequencing by 16S rRNA region, showing a similarity of 99.72% with Paenibacillus polymyxa HGPJ-62 in the GenBank database (NCBI). The optimized medium composition and culture conditions for strain Paenibacillus polymyxa M6 were determined as follows: the β-1,3-glucanase induction medium comprised the following components: K₂HPO₄·3H₂O 1.3 g; MgSO₄·7H₂O 1 g; KCl 0.5 g; yeast extract 0.5 g; NaNO₃ 1 g; oat flour 5 g; pH = 6, incubation temperature 40–50°C for 24 hours, shaking speed 180 rpm, and inoculum ratio 1%. The β-1,3-glucanase activity reached 1.5 U/mL. The present study highlights the β-1,3-glucanase biosynthesis by strain M6, demonstrating its suitability for development and application for prevent gummosis disease in Thanh Tra pomelo trees as well as in controlling fungal pathogens with glucan-dominant cell walls.