One-pot bioethanol production from brewery spent grain using the ethanologenic Escherichia coli MS04

WAGNER, E.; ESTEFANIA SIERRA-IBARRA; ROJAS, N. L; MARTÍNEZ, A

RENEWABLE ENERGY

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2022 vol. 189 p. 717 - 725

0960-1481

Lignocellulosic biomass residues constitute an alternative for energy generation. In this work, brewery spent grain (BSG) were used as feedstock to produce ethanol using a recombinant Escherichia coli MS04 strain. A sequential process involving pretreatment, saccharification and fermentation steps in one-pot bioreactors, without solids removal, was proposed. Different diluted acid pretreatment times (1 and 1.5 h) using a 15% (w/w) solids load to obtain high monosaccharides yields were evaluated. After the pretreatment and saccharification, the proposed strategy converted the polysaccharides contained in BSG into fermentable pentoses and hexoses, obtaining a syrup composed by monosaccharides (60 g/L), furfural (0.39 g/L), hydroxymethylfurfural (0.07 g/L) and acetic acid (2.56 g/L), which was afterwards fermented for the bioethanol generation. After 30 h, ethanol production resulted in 29.5 ± 0.41 g/L, which means a volumetric productivity of 0.98 g EtOH/Lh based on the consumption of the glucose, xylose and arabinose. These results mean a global yield of 251 L EtOH/ton BSG of this feedstock and were accomplished without the inhibition caused by acetic acid formation (6.87 g/L). Furthermore, the proposed process in this work was developed in a sequential pathway, which comprises an operational advantage to exploit the BSG in the production of second-generation bioethanol.