Bagasse hydrolyzates from Agave tequilana as substrates for succinic acid production by Actinobacillus succinogenes in batch and repeated batch reactor

• Lignocellulosic residues can be used as a source of hydrolyzates for fermentation.
• Enzymatic hydrolyzates were free of furfural and hydroxymethylfurfural.
• Production of succinic acid was faster by using enzymatic hydrolyzates.
• 33.6 g/L succinic acid was obtained from 87.2 g/L fermentable sugars by repeated batch.
• Immobilization of cells reduced significantly the time of fermentation.

The aim of this work was to obtain fermentable sugars by enzymatic or acid hydrolyses of Agave tequilana Weber bagasse in order to produce succinic acid with Actinobacillus succinogenes. Hydrolyses were carried out with mineral acids (sulfuric and hydrochloric acids) or a commercial cellulolytic enzyme, and were optimized statistically by a response surface methodology, having as factors the concentration of acid/enzyme and time of hydrolysis. The concentration of sugars obtained at optimal conditions for each hydrolysis were 21.7, 22.4 y 19.8 g/L for H2SO4, HCl and the enzymatic preparation respectively. Concerning succinic acid production, the enzymatic hydrolyzates resulted in the highest yield (0.446 g/g) and productivity (0.57 g/L h) using A. succinogenes in a batch reactor system. Repeated batch fermentation with immobilized A. succinogenes in agar and with the enzymatic hydrolyzates resulted in a maximum concentration of succinic acid of 33.6 g/L from 87.2 g/L monosaccharides after 5 cycles in 40 h, obtaining a productivity of 1.32 g/Lh.