Characterization of a thermostable PL-31 family alginate lyase from Paenibacillus ehimensis and its application for alginate oligosaccharides bioproduction

Currently, people pay more attention to marine sugars, because of their unique physiological effects. Alginate oligosaccharides (AOS) are the degradation products of alginate and have been used in food, cosmetic, and medicine fields. AOS display good physical characteristics (low relative molecular weight, good solubility, high safety, and high stability) and excellent physiological functions (immunomodulatory, antioxidant, antidiabetic, and prebiotic activities). Alginate lyase plays a key role in the AOS bioproduction. In this study, a novel PL-31 family alginate lyase from Paenibacillus ehimensis (paeh-aly) was identified and characterized. It was extracellularly secreted in E. coli and exhibited a preference for the substrate poly ss-D-mannuronate. Using sodium alginate as the substrate, it showed the maximum catalytic activity (125.7 U/mg) at pH 7.5 and 55.C with 50 mM NaCl. Compared with other alginate lyases, paeh-aly exhibited good stability. About 86.6% and 61.0% residual activity could be maintained after 5 h incubation at 50 and 55.C respectively, and its Tm value was 61.5. C. The degradation products were AOS with DP 2-4. Paeh-aly demonstrated strong promise for AOS industrial production because of its excellent thermostability and efficiency.

Automated summary

Currently, marine sugars have gained increased attention due to their unique physiological effects. Alginate oligosaccharides (AOS), degradation products of alginate, find applications in the fields of food, cosmetic, and medicine. A novel alginate lyase from Paenibacillus ehimensis (paeh-aly) showed potential for industrial production of AOS due to its excellent thermostability and efficiency.