A seawater-based biorefining strategy for fermentative production and chemical transformations of succinic acid

Abstract

In this manuscript, the possibility of utilising seawater instead of fresh water and a synthetic mixture of minerals as alternative water and mineral sources in succinic acid (SA) fermentations was investigated. Seawater tolerance experiments demonstrated that the specific growth rate of Actinobacillus succinogenes was only slightly affected when more than 60% synthetic seawater was used, but no major significant inhibition of cell growth and SA production were observed even when fresh water was replaced by 100% synthetic seawater. The possibility of replacing a semi-defined medium with fresh water by wheat-derived media with natural seawater was carried out sequentially. Results showed that besides the usage as a water source, seawater also can be used as a mineral supplement to the wheat-derived media, forming a nutrient-complete medium for succinic acid production. In a fermentation using only wheat-derived medium and natural seawater, 49 g L⁻¹succinic acid was produced with a yield of 0.94 g per g and a productivity of 1.12 g L⁻¹ h⁻¹. Interestingly, compounds present in seawater had a major effect on rates of reactions of a range of transformations of SA including esterifications and amidations in comparison with reactions run under similar conditions using distilled water. While salts and related compounds improved the rates of reaction in the amidation of SA compared to plain water, a significant reduction in activity and catalyst deactivation was found in the esterifications of SA using Starbon® acids as catalysts.