An automated workflow for the rapid increase of hydrolytic enzyme concentration for short- chain carboxylic acid production from lignocellulosic biomass

Abstract

Abstract Background. Short-chain carboxylic acids are interesting building blocks that can be synthesized from biogenic residues with the so-called dark fermentation. One challenge though is the hydrolysis of lignocellulosic residues to make them accessible for whole cell biotransformation. Accessibility can be achieved through conversion of lignocellulose through microbial exoenzymes. In this study, bacteria and fungi were isolated from different lignocellulose-containing feedstock. A workflow of an automated screening with the isolated strains for their ability to accumulate short-chain carboxylic acids in fermentation was elaborated. The screening was performed with and without addition of fungal enzymes. Results. Results show a three-fold increase in acetic acid concentration and nearly a six-fold increase in succinic acid concentration if the feedstock was pre-treated in comparison to untreated feedstock. When adding the enzyme-containing supernatant to a continuous dark fermentation with wood barks as feedstock, the acid concentration increased remarkably from 1 to 2.6 g⋅L− 1. Conclusion. The methodology, thus, is suitable to identify strains and enzyme mixtures for improving hydrolysis of complex lignocellulosic feedstock.