Effective Comprehensive Utilization Strategy for Upgrading Red Seaweed via Chemocatalysis and a Newly Isolated Pseudomonas rhodesiae in Tandem

Abstract

Red seaweed is a kind of important renewable biomass owing to its great advantages over terrestrial biomass, but present research mainly focused on the biorefinery of fermentable sugars from red seaweeds only. In this study, we proposed an effective comprehensive utilization strategy for upgrading red seaweed (Gelidium amansii) to d-galactose and 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) via chemocatalysis and biocatalysis in tandem. With G. amansii as raw feedstock, high yields of d-galactose (85.5%) and 5-hydroxymethylfurfural (HMF) (50.9%) were first achieved by oxalic acid catalysis. HMF was separated and further selectively oxidized to HMFCA by whole cells of Pseudomonas rhodesiae NL2019 with a yield of 83.9%. Particularly, G. amansii hydrolysate was also used as the carbon source (d-galactose) for cell growth and as an inducer (HMF) to promote the catalytic capacity of P. rhodesiae cells. In this way, we established a cost-competitive, highly efficient, and environmentally friendly chemoenzymatic approach for the simultaneous valorization of all components of red seaweed.