Display of Bacterial Exochitanase on Bacillus subtilis Spores Improved Enzyme Stability and Recyclability

Chitin is the second most prevalent polysaccharide found in nature, following cellulose. Amino-oligosaccharides, the byproducts of chitin degradation, exhibit favorable biological properties and potential for various uses. Chitinases play a crucial function in the breakdown of chitin, and their exceptionally effective production has garnered significant interest. Here, in this study, the exochitinase PbChiA, obtained from Paenibacillus barengoltzii, was recombinantly produced and immobilized using the CotG surface protein of Bacillus subtilis WB800N. The resulting strain Bacillus subtilis WB800N pHS-CotG-Chi exhibited exceptional heat stability and efficacy across various pH levels. The chitinolytic activity of the enzyme, which had been isolated and immobilized on the spore surface, was measured to be approximately 16.06 U/mL. Including Ni²⁺, Zn⁺², and K⁺, and EDTA at various concentration levels in the reaction system, has significantly enhanced the activity of the immobilized enzyme. The immobilized exochitinase demonstrated a notable rate of recycling, as the recombinant spores sustained a relative enzyme activity of more than 70% after three cycles and 62.7% after four cycles. These findings established a basis for additional investigation into the role and practical use of the immobilized bacterial exochitinase in industry.