Valorization of Gelidium amansii for dual production of D-galactonic acid and 5-hydroxymethyl-2-furancarboxylic acid by chemo-biological approach

Peng Liu,Feng Zhou,Jiaxiao Xie,Huanghong Tan,Lihua Zou,Jia Ouyang

doi:10.1186/s12934-020-01357-6

Abstract

BackgroundMarine macroalgae Gelidium amansii is a promising feedstock for production of sustainable biochemicals to replace petroleum and edible biomass. Different from terrestrial lignocellulosic biomass, G. amansii is comprised of high carbohydrate content and has no lignin. In previous studies, G. amansii biomass has been exploited to obtain fermentable sugars along with suppressing 5-hydroxymethylfurfural (HMF) formation for bioethanol production. In this study, a different strategy was addressed and verified for dual production of D-galactose and HMF, which were subsequently oxidized to D-galactonic acid and 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) respectively via Pseudomonas putida.ResultsG. amansii biomass was hydrolyzed by dilute acid to form D-galactose and HMF. The best result was attained after pretreatment with 2% (w/w) HCl at 120 °C for 40 min. Five different Pseudomonas sp. strains including P. putida ATCC 47054, P. fragi ATCC 4973, P. stutzeri CICC 10402, P. rhodesiae CICC 21960, and P. aeruginosa CGMCC 1.10712, were screened for highly selective oxidation of D-galactose and HMF. Among them, P. putida ATCC 47054 was the outstanding suitable biocatalyst converting D-galactose and HMF to the corresponding acids without reduced or over-oxidized products. It was plausible that the pyrroloquinoline quinone-dependent glucose dehydrogenase and undiscovered molybdate-dependent enzyme(s) in P. putida ATCC 47054 individually played pivotal role for d-galactose and HMF oxidation. Taking advantage of its excellent efficiency and high selectivity, a maximum of 55.30 g/L d-galactonic acid and 11.09 g/L HMFCA were obtained with yields of 91.1% and 98.7% using G. amansii hydrolysates as substrate.ConclusionsValorization of G. amansii biomass for dual production of D-galactonic acid and HMFCA can enrich the product varieties and improve the economic benefits. This study also demonstrates the perspective of making full use of marine feedstocks to produce other value-added products.

Highlights

Marine macroalgae Gelidium amansii is a promising feedstock for production of sustainable biochemicals to replace petroleum and edible biomass
To sum up, taking advantage of the excellent efficiency and selectivity of P. putida ATCC 47054, efficient valorization of G. amansii biomass for dual production of D-galactonic acid and hydroxymethyl-2-furancarboxylic acid (HMFCA) at high yields was achieved for the first time, and these results further proved that algae biomass could be a promising feedstock for biochemicals production
The non-lignocellulosic feedstock of G. amansii was exploited for dual production of D-galactonic acid and HMFCA

Summary

Introduction

Marine macroalgae Gelidium amansii is a promising feedstock for production of sustainable biochemicals to replace petroleum and edible biomass. Different from terrestrial lignocellulosic biomass, G. amansii is comprised of high carbohydrate content and has no lignin. G. amansii biomass has been exploited to obtain fermentable sugars along with suppressing 5-hydroxymethylfurfural (HMF) formation for bioethanol production. Macroalgae has superior characteristics as advanced feedstocks, including no lignin, high carbohydrate content, rapid grown rate with fixation of more CO2 than wood-biomass, and easy cultivation without the need of arable land and freshwater [3, 4]. Gelidium amansii and Gracilaria gracilis are two wellknown agarophyte red macroalgae, which comprise polysaccharide complexes of fibrin (cellulose) and agar (agarose). Many studies focused on suppressing the inhibitor generation during pretreatment of red macroalgae and investigating the effects of HMF on fermentative process [7]

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Conclusion