Isolation and Characterization of Enterobacter sp Capable towards Tolerating Degradation Products and Fermenting Pentoses

Abstract

<p>The depletion of fossil fuel resources, in addition to the growing demand for energy, has prompted the development of renewable energies, including bioethanol from lignocellulosic biomass. The acid pretreatment of hemicellulose releases inhibiting compounds in addition to xylose. With the possibility of exploitation of lignocellulose as a fermentation substrate, we isolated an <em>Enterobacter </em>characterized by its ability to ferment xylose and tolerate high concentrations of inhibitors. The selection was performed in media containing different carbon and energy sources; glucose, cellobiose, CMC, furfural and 5-HMF. Characterization strategies of the selected strain such as, xylose concentration (from 25 g liter-1 to 100 g liter-1), furfural (0 mM to 25 mM), cell immobilization, were used to quantify the maximum yield of ethanol produced. The results obtained show that our strain can ferment up to 100 g liter-1 of xylose in the presence of 20 mM furfural at 37°C to produce ethanol with a maximum yield of 2.22 g liter- 1 for 24 h under 160 rpm magnetic stirring. The results obtained in this study suggest that the isolated <em>Enterobacter </em>sp. is a promising strain for the bioconversion of lignocellulosic biomass pretreatment hydrolysate into bioethanol.</p><p> </p>