d-Mannose and l-ribose are two important monosaccharides, which have attracted public attention recently because of their great application potentials in food, cosmetic and pharmaceutical industries. Sugar isomerases catalyze the sugar isomerization and therefore can be used as the biocatalysts for production of the high-value sugars from inexpensive sugars. l-arabinose isomerase catalyzes the conversion of l-arabinose to l-ribulose, while d-lyxose isomerase catalyzes l-ribulose and d-fructose to l-ribose and d-mannose, respectively. In this paper, a putative d-LI from Bacillus velezensis (BvLI) was identified, characterized and used to produce d-mannose and l-ribose from d-fructose and l-arabinose, respectively. The recombinant BvLI exhibited a maximum activity at 55 °C and pH 6.5, in the presence of 0.1 mM Co2+. Approximately 110.75 g/L d-mannose was obtained from 500 g/L d-fructose in 6 h by the recombinant BvLI, and approximately 105 g/L l-ribose was obtained from 500 g/L l-arabinose in 8 h by the successive biocatalysis of l-arabinose isomerase from Bacillus licheniformis (BlAI) and BvLI.

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