Biotechnological synthesis of succinic acid by actinobacillus succinogenes by exploitation of lignocellulosic biomass

Succinic acid is increasingly used in pharmaceutical industries, for the production of additives in food industries, in agriculture and in refinery processes as a precursor of many chemical compounds among which the most important is the succinate salt. It is also used as an ion chelator and surfactant, and for the biochemicals production. Currently, succinic acid is mainly produced through chemical petroleum-based processes, usually from n-butane using maleic anhydride. However, the use of petrochemical feedstocks raises serious environmental problems, due to the higher values of temperature and pressure required. The biotechnological production of succinic acid by microbial conversion of lignocellulosic biomass is attracting growing interest due to the environmental and economic advantages offered. This research is focused on the exploitation of Arundo donax (Giant reed) as a source of lignocellulosic biomass. Arundo donax is a perennial crop particularly suitable for energy production, as it offers high yields per hectare, even in partially fertile or polluted soils, not used for agriculture. Hydrolyzate of Arundo donax will be used as growth media for the Actinobacillus succinogenes 130Z, a bacterium typically found in the bovine rumen, that is recognized as one of the most promising for the biotechnological production of succinic acid, as it is able to produce higher concentrations of succinic acid. The experimental analysis is carried out to optimize the production of succinic acid taking into account the effect of the most critical parameters of the process (microbial biomass, pH, reducing sugars, volatile fatty acids, and succinic acid). Tests have shown that in 48h the sugars are completely biodegraded with a total production of bio-succinic acid of 5.9 g for 9.1 g of reducing sugars, an hourly production 0.12 g h-1 with a yield equal to 65%.