Rational Design of the Chitinase from Paenibacillus Barengoltzii for Efficient Production of Lacto- N -Triose II from Chitin Powder

Chitin, a major component of shellfish waste, is a promising resource for producing bioactive compounds. To enhance the hydrolysis efficiency of Chitinase, a combined engineering strategy was employed to optimize the Chitinase (mPbChi70) from Paenibacillus barengoltzii. Through computer-aided rational design and chitin-binding domain modification, an enhanced mutant, m-mPbChi70 (Trp163Phe/Asp199Glu/Lys688Pro), was developed with significantly improved catalytic performance. The mutant exhibited optimal activity at pH 6.0 and 50 °C. Its specific activity toward chitin powder increased by 24.1% compared to mPbChi70. During chitin powder hydrolysis, m-mPbChi70 exhibited a 1.8-fold increase in N-acetyl-chitobiose yield (39.1 mmol·L⁻¹) and a 67.4% reduction in N-acetyl-d-glucosamine accumulation. Furthermore, the mutant enabled efficient and sustainable production of lacto-N-triose II (LNT2) from chitin powder, achieving a yield of 15.0 g·L¹. This study not only presents an innovative strategy for Chitinase engineering but also offers a sustainable and cost-effective approach for converting chitin waste into high-value LNT2.