Abstract
Succinic acid is a precursor for many chemicals in the food, pharmaceutical, cosmetic, and biodegradable plastics industries. Nowadays, the biotechnological route to produce succinic acid is focused on processes based on the fermentation of natural materials characterized by high fraction of carbohydrates. Actinobacillus succinogenes is proposed in the literature as a promising strain for the production of succinic acid. Indeed, A. succinogenes may utilize a wide spectrum of carbohydrates as carbon sources. Moreover, the CO2 required for the fermentation allows to include the biotechnological route among the carbon capture and conversion processes.
A key issue of fermentation processes aimed at producing succinic acid is the feedstock cost. Pre-requisites of the feedstock are: availability at high mass flow rate over all the year, and non-competitive with (human and animal) food. Lignocellulosic biomass is a potential feedstock because it fulfils the listed pre-requisites.
This contribution reports the characterization of succinic acid fermentation by A. succinogenes 130Z adopting as carbon source sugars representative of the hydrolysis of lignocellulosic biomass: glucose, mannose, arabinose, and xylose. Batch fermentation tests were carried out using single sugar as carbon source for a systematic characterization of the conversion process of the investigated sugars.
The conversion process was characterized in terms of concentration of biomass, sugars, and acids as well as of pH. The time-resolved data were processed to assess the sugar conversion, the succinic acid yield, and the productivity for each of the investigated sugars.
A. succinogenes was able to convert all investigated sugars into succinic acid using MgCO3 as an indirect CO2 source. Glucose was the sugar characterized by the best performance when the initial concentration was set at 40 g/L. The performances did not depend on the investigated sugars if the initial concentration was quite low (<5 g/L).
