Lignocellulosic acid hydrolysis inhibitor impact on 5-hydroxymethylfurfural biotransformation into 2, 5-furandicarboxylic acid using immobilised Burkholderia cells

Optimization of operating parameters for 2,5-furandicarboxylic acid recovery using electrodialysis with bipolar membrane and traditional electrodialysis systems

Electrodialysis (ED) is an eco-friendly and feasible method to separate or recover ionic compounds by electric field attraction and configuration of ion exchange membranes. Strain Burkholderia sp. H-2 could biotransform 5-hydroxymethylfurfural (5-HMF) into a green platform compound, 2,5-furandicarboxylic acid (FDCA), using a bioreactor system. In this study, electrodialysis with the bipolar membrane (EDBM) and traditional ED systems were applied to recover and concentrate FDCA. Artificial and real FDCA effluents of the 5-HMF biotransformation bioreactor were used as the feedstock to establish the optimal conditions for FDCA recovery. The optimal FDCA concentration and pH of the artificial FDCA effluent were 2100 mg/L and 5, respectively. The suitable current density of the EDBM was 8.93 mA/cm2. For FDCA recovery and concentration using the ED, the feedstock volume and FDCA concentration in the concentration chamber were 1.5 L and 1000 mg/L, respectively. The FDCA recovery efficiency of the real FDCA effluent was 55.6 %. Suppose the pretreatment procedure of the real bioreactor effluent is further optimized. It is believed to benefit the enhancement of FDCA recovery efficiency and reduce energy consumption.

Microbial contributions to sustainable paddy straw utilization for economic gain and environmental conservation

Paddy straw is a versatile and valuable resource with multifaceted benefits for nutrient cycling, soil health, and climate mitigation. Its role as a rich nutrient source and organic matter significantly enhances soil vitality while improving soil structure and moisture retention. The impact of paddy straw extends beyond traditional agricultural benefits, encompassing the promotion of microbial activity, erosion control, and carbon sequestration, highlighting its crucial role in maintaining ecological balance. Furthermore, the potential of paddy straw in bioenergy is explored, encompassing its conversion into biogas, biofuels, and thermal energy. The inherent characteristics of paddy straw, including its high cellulose, hemicellulose, and lignin content, position it as a viable candidate for bioenergy production through innovative processes like pyrolysis, gasification, anaerobic digestion, and combustion. Recent research has uncovered state-of-the-art techniques and innovative technologies capable of converting paddy straw into valuable products, including sugar, ethanol, paper, and fiber, broadening its potential applications. This paper aims to underscore the possibilities for value creation through paddy straw, emphasizing its potential use in bioenergy, bio-products, and other environmental applications. Therefore, by recognizing and harnessing the value of paddy straw, we can advocate for sustainable farming practices, reduce waste, and pave the way for a resource-efficient circular economy. Incorporating paddy straw utilization into agricultural systems can pave the way for enhanced resource efficiency and a more sustainable circular economy.

Enzymatic Cascade for the Synthesis of 2,5-Furandicarboxylic Acid in Biphasic and Microaqueous Conditions: 'Media-Agnostic' Biocatalysts for Biorefineries

5-hydroxymethylfurfural (HMF) is produced upon dehydration of C6 sugars in biorefineries. As the product, it remains either in aqueous solutions, or is in situ extracted to an organic medium (biphasic system). For the subsequent oxidation of HMF to 2,5-furandicarboxylic acid (FDCA), 'media-agnostic' catalysts that can be efficiently used in different conditions, from aqueous to biphasic, and to organic (microaqueous) media, are of interest. Here, the concept of a one-pot biocatalytic cascade for production of FDCA from HMF was reported, using galactose oxidase (GalOx) for the formation of 2,5-diformylfuran (DFF), followed by the lipase-mediated peracid oxidation of DFF to FDCA. GalOx maintained its catalytic activity upon exposure to a range of organic solvents with only 1 % (v/v) of water. The oxidation of HMF to 2,5-diformylfuran (DFF) was successfully established in ethyl acetate-based biphasic or microaqueous systems. To validate the concept, the reaction was conducted at 5 % (v/v) water, and integrated in a cascade where DFF was subsequently oxidized to FDCA in a reaction catalyzed by Candida antarctica lipase B.

Whole Cell Biocatalysis of 5-Hydroxymethylfurfural for Sustainable Biorefineries

The implementation of cost-effective and sustainable biorefineries to substitute the petroleum-based economy is dependent on coupling the production of bioenergy with high-value chemicals. For this purpose, the US Department of Energy identified a group of key target compounds to be produced from renewable biomass. Among them, 5-hydroxymethylfurfural (HMF) can be obtained by dehydration of the hexoses present in biomass and is an extremely versatile molecule that can be further converted into a wide range of higher value compounds. HMF derivatives include 2,5-bis(hydroxymethyl)furan (BHMF), 5-hydroxymethyl-furan-2-carboxylic acid (HMFCA), 2,5-diformylfuran (DFF), 5-formyl-2-furancarboxylic acid (FFCA) and 2,5-furandicarboxylic acid (FDCA), all presenting valuable applications, in polymers, bioplastics and pharmaceuticals. Biocatalysis conversion of HMF into its derivatives emerges as a green alternative, taking into account the high selectivity of enzymes and the mild reaction conditions used. Considering these factors, this work reviews the use of microorganisms as whole-cell biocatalysts for the production of HMF derivatives. In the last years, a large number of whole-cell biocatalysts have been discovered and developed for HMF conversion into BHMF, FDCA and HMFCA, however there are no reports on microbial production of DFF and FFCA. While the production of BHMF and HMFCA mainly relies on wild type microorganisms, FDCA production, which requires multiple bioconversion steps from HMF, is strongly dependent on genetic engineering strategies. Together, the information gathered supports the possibility for the development of cell factories to produce high-value compounds, envisioning economical viable biorefineries.