Myrosinase is a biotechnological tool for the preparation of sulforaphane and sulforaphene with a variety of excellent biological activities. In this study, a gene encoding the novel glycoside hydrolase family 3 (GH3) myrosinase Rmyr from Rahnella inusitata was heterologously expressed in Escherichia coli BL21 (DE3). The purified Rmyr shows the highest activity at 40 °C and pH 7.0; meanwhile, its half-life at 30 °C reaches 12 days, indicating its excellent stability. Its sinigrin-, glucoraphenin-, and glucoraphanin-hydrolyzing activities were 12.73, 4.81, and 6.99 U/mg, respectively. Rmyr could efficiently degrade the radish seedderived glucoraphenin and the broccoli seed-derived glucoraphanin into sulforaphene and sulforaphane within 10 min with the highest yields of 5.07 mg/g radish seeds and 9.56 mg/g broccoli seeds, respectively. The highest conversion efficiencies of sulforaphane from glucoraphanin and sulforaphene from glucoraphenin reached up to 92.48 and 97.84%, respectively. Therefore, Rmyr is a promising and potent biocatalyst for efficient and large-scale preparation of sulforaphane and sulforaphene.

Fucoidan is one of the main polysaccharides of brown algae and echinoderm, which has nutritional and pharmacological functions. Due to the low molecular weight and exposure of more sulfate groups, oligo-fucoidan or fucoidan oligosaccharides have potential for broader applications. In this research, a novel endo-α-1,4-L-fucoidanase OUC-FaFcn1 which can degrade fucoidan into oligo-fucoidan was discovered from the fucoidan-digesting strain Flavobacterium algicola 12,076. OUC-FaFcn1 belongs to glycoside hydrolases (GH) family 107 and shows highest activity at 40 °C and pH 9.0. It can degrade the α-1,4 glycosidic bond, instead of α-1,3 glycosidic bond, of the fucoidan with a random tangent way to generate the principal product of disaccharide, which accounts for 49.4% of the total products. Therefore, OUC-FaFcn1 is a promising bio-catalyst for the preparation of fucoidan-derived disaccharide. These results further enrich the resource library of fucoidanase and provide the basis for the directional preparation of fucoidan-derived oligosaccharide with specific polymerization.

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λ-Carrageenase with high activity is an effective and environmentally friendly tool enzyme for the preparation of λ-carrageenan oligosaccharides with various biological activities. Herein, a novel GH150 (glycoside hydrolases family 150) λ-carrageenase OUC-CglA from Maribacter vaceletii was heterologously expressed, purified, and characterized. The recombinant OUC-CglA performs strict selectivity toward λ-carrageenan with a specific activity of 418.7 U/mg under its optimal reaction conditions of 20 °C and pH 7.0. Additionally, OUC-CglA is a typical cold-adapted λ-carrageenase because it unfolds 90% and 63% of its maximum activity at 15 and 10 °C, respectively. The hydrolysis process suggests that OUC-CglA is an endotype λ-carrageenase with the final products consisting of λ-neocarrabiose, λ-neocarratetraose, λ-neocarrahexaose, and other long-chain λ-neocarrageenan oligosaccharides. As a result, high activity, cold-adaptation, and principal products of OUC-CglA make it a potential biocatalyst for the effective preparation of λ-carrageenan oligosaccharides.