Butanol production from Thai traditional beverage (Sato) factory wastewater using newly isolated Clostridium beijerinckii CUEA02

Abstract

Sato, a Thai traditional beverage, wastewater (STW) contains residual rice constituents with high chemical and biological oxygen demands, and so its disposal is an environmental problem. To solve this, the potential of STW for butanol production, which has never been evaluated for use in ABE fermentation, is reported. Clostridium beijerinckii CUEA02, the strain producing the highest butanol level in this study, was isolated from natural sources in Thailand. Isolate CUEA02 was closely related to C. beijerinckii with an average nucleotide identity of 95.14% and could grow and produce butanol from various carbon sources. The butanol production was 8.32 ± 0.08 g/L in flask fermentation under an initial pH of 6.5, 35 °C, 10% (v/v) inoculum size, and 50 g/L of glucose. To evaluate the potential of STW, it was diluted 0.1x, 0.2x, 0.3x, and 0.4x for ABE production by CUEA02, with the 0.1x dilution giving the highest butanol yield (0.23 g/g). To improve the butanol production, the initial pH was adjusted from 4.75 to 6.5, resulting in a 2.13-fold enhanced butanol yield (0.49 g/g). Moreover, the addition of yeast extract at 2 g/L increased the butanol production by up to 29% in STW using C. beijerinckii CUEA02.