Butyric Acid Production from Waste Wood Hydrolysate (WWH) by Clostridium sp. S1

Abstract

Lignocellulosic biomass is one of the most abundant renewable resources and composed of carbohydrate polymers (cellulose, hemicellulose). Among the component, hemicellulose contains mannan, galactan, and acetic acid as well as xylose. Therefore, it is important to find microbes utilizing a wide range of carbohydrates for using lignocellulose as a carbon source. In this study, we isolated a butyric acid- producing bacterium, Clostridium sp. S1, which was capable of utilizing various carbohydrates. Prior to carrying out waste wood hydrolysate fermentation, we investigated the ability of Clostridium sp. S1 to ferment representative sugars derived from lignocellulosic biomass. In batch cultures, Clostridium sp. S1 successfully produced butyric acid from glucose, galactose, mannose, and xylose. Furthermore, Clostridium sp. S1 was found to utilize acetic acid generated as a by-product after acid hydrolysis of lignocellulosic biomass, resulting in an increase of butyric acid yield. When waste wood was treated through concentrate acid hydrolysis, 31.3 g/L of total carbohydrates was obtained and Clostridium sp. S1 successfully produced 11.9 g/L of butyric acid as the only product using the waste wood hydrolysate.