An effective method for the preparation of carrageenan oligosaccharides directly from Eucheuma cottonii using cellulase and recombinant κ-carrageenase

Carrageenan oligosaccharides have drawn considerable attention for their potential application in various technologies. The objective of this study was to develop a high-efficiency method to prepare carrageenan oligosaccharides directly from Eucheuma cottonii using cellulase and recombinant κ-carrageenase. The recombinant κ-carrageenase was produced by Escherichia coli BL21-HTa-cgkZ, which expresses κ-carrageenase from a marine bacterium. Dried seaweed was first digested with cellulase at pH 5.0 and 50 °C for 2 h, and then with recombinant κ-carrageenase. To improve oligosaccharide recovery, the parameters of carrageenase hydrolysis were optimized using central composite design and validated. Using this method, E. cottonii oligosaccharides (ECO) were recovered with a 38% yield. High-performance gel permeation chromatography (HPGPC), Fourier transform infrared spectrometry (FT-IR), and electrospray ionization-mass spectrometry (ESI-MS) results indicated that ECO possess characteristics specific to carrageenan oligosaccharides, in particular hexasaccharides.