Abstract: Compared with terrestrial biomass, marine biomass, called the third generation of biomass resources, has attracted more and more attention due to its higher photosynthetic efficiency, faster growth speed, higher carbohydrate content and zero lignin content. Red algae are typical large seaweeds enriched with polysaccharides in the cell wall. In this paper, the geographical distribution and chemical composition of red algae are described with a special focus on recent progress in the biotransformation of red algal polysaccharides for the enzymatic preparation of agar oligosaccharide and 3,6-anhydro-L-galactose and the microbial production of ethanol and organic acids. Moreover, future directions for the utilization of red algal biomass are discussed.

Key words: red algae; agar; carrageenan; galactose; 3,6-anhydro-L-galactose