A High-Yielding Enzymatic Process for Production of Bioactive β-1,3-Glucan Oligosaccharides with Defined Size

Abstract

The study is to develop a bioprocess to depolymerize curdlan for production of β-1,3 oligosaccharides with a uniform size. A codon-optimized Streptomyces laminarinase was expressed in an E. coli system, resulting in an enzyme preparation (19.1 U/L) highly active on solid curdlan substrate without any pre-treatment. In a preparative scale reaction at pH 5.5 and 55°C, 90% conversion and a product concentration close to 27 g/L were achieved within 6 hours. The major product was identified as β3-glucan pentasaccharide based on HPLC, TLC, and MS analyses. A single-enzyme based bioprocess was highly efficient in deriving β3-glucan pentasaccharide from solid curdlan. Enzyme to curdlan ratio and reaction time are critical parameters for high-yield production of β3-glucan pentasaccharide from curdlan.