GSE119357
Transcriptomic analysis of Vibrio sp. dhg in different sugar media.
Brown macroalgae holds an enormous potential as a future feedstock because it rapidly forms large biomasses and has high carbohydrate content (35% of its dry weight consists of alginate and mannitol). However, utilization of brown macroalgae by conventional microbial platforms (e.g., Escherichia coli and Saccharomyces cerevisiae) has been limited due to the inability of these platforms to metabolize alginate. Although recent studies engineered them to utilize alginate, their growth rates and metabolic activities are still too low for industrial applications, likely due to the unoptimized expression of multiple xenogeneic genes. Here, we isolated Vibrio sp. dhg, a novel, fast-growing bacterium that has been naturally evolved for efficient alginate assimilation (growth rate = 0.98 h-1). Especially, both the growth rate and sugar uptake rate of V. sp. dhg are substantially higher than the rates of E. coli for most biomass-derivable sugars. Based on our systematic characterization of its metabolism and gene expression architecture, we were able to develop a genetic toolbox for its engineering. By using this microorganism, we successfully demonstrated its ability to produce a broad spectrum of chemicals from alginate-mannitol mixtures with high productivities (1.1 g ethanol/L/h, 1.3 g 2,3-butanediol and acetoin/L/h, and 0.69 mg lycopene/L/h). Collectively, the V. sp. dhg strain is a powerful platform for the conversion of brown macroalgae sugars whose usage will dramatically accelerate the production of value-added biochemicals in the future. Overall design: Vibrio sp. dhg strain was cultivated in a minimal medium supplemented in glucose, alginate, or mannitol as a sole carbon source.