Novel Isolates for Biological Detoxification of Lignocellulosic Hydrolysate

Abstract

In this paper, two new strians, Issatchenkia occidentalis (Lj-3, CCTCC M 2006097) and Issatchenkia orienalis (S-7, CCTCC M 2006098), isolated from different environments on solid media, were used in the detoxification process of the hemicellulosic hydrolysate of sugarcane bagasse. High-pressure liquid chromatography elution curve of UV-absorption compounds represented by acetic acid, furfural, and guaiacol (toxic compounds found in the hemicellulosic hydrolysate) showed that several chromatographic peaks were evidently diminished for the case of detoxified hydrolysate with isolate strains compared to the high peaks resulted for no detoxified hydrolysate. It was clear that these inhibitors were degraded by the two new isolates during their cultivation process. Fermentation results for the biodetoxified hydrolysate showed an increase in xylitol productivity (Q (p)) by 1.97 and 1.95 times (2.03 and 2.01 g l(-1) h(-1)) and in xylitol yield (Y (p)) by 1.72 and 1.65 times (0.93 and 0.89 g xylitol per gram xylose) for hydrolysate treated with S-7 and Lj-3, respectively, in comparison with no detoxified hydrolysate (1.03 g l(-1) h(-1) and 0.54 g xylitol per gram xylose). This present work demonstrated the importance of Issatchenkia yeast in providing an effective biological detoxification approach to remove inhibitors and improve hydrolysate fermentability, leading to a high xylitol productivity and yield.

Biological detoxification of different hemicellulosic hydrolysates using Issatchenkia occidentalis CCTCC M 206097 yeast

“…The employment of microorganisms as detoxifying agents of hemicellulosic hydrolysates is a methodology without significant loss of volume and is economically more viable than other processes [16]. In this work, there were no losses greater than 5% of volume when treating NCH and FCH with this yeast strain.…”

“…The yeast Issatchenkia occidentalis CCTCC M 206097, isolated from industrial wastes containing phenolic compounds [16], was used as a detoxification agent for different hydrolysates. The culture was kept in agar malt extract at 4°C.…”

Screening of Yeasts for Selection of Potential Strains and Their Utilization for In Situ Microbial Detoxification (ISMD) of Sugarcane Bagasse Hemicellulosic Hydrolysate

“…Hou-Rui et al [22] also, used P. occidentalis CCTCC M 206097 to remove fermentation inhibitors from sugarcane bagasse hemicellulosic hydrolysates and confirmed that this strain was able to remove 100 % of 2.0 g/l acetic acid and 0.02 g/l furfural. Likewise, Fonseca et al [21] employed the same yeast strain P. occidentalis CCTCC M Table 4 Initial and final concentrations of toxic compounds in hemicellulose hydrolyzate treated biologically by Picchia occidentalis 206097 and reported 6.1 % removal of 3.3 g/l acetic acid, 100 % of 0.02 g/l of HMF and 100 % of 0.16 g/l furfural, after 72 h of biological detoxification.…”

Isolation and Characterization of Yeasts Able to Assimilate Sugarcane Bagasse Hemicellulosic Hydrolysate and Produce Xylitol Associated with Veturius transversus (Passalidae, Coleoptera, and Insecta)

“…However, according to Barnett [20], biochemical profiles may be used as complementary information but cannot be conclusive for taxonomic identification because they can present high variation, with it being recommended to evaluate genomics data. According to Hou-Rui et al [21], up to 1% of nucleotide substitution in a ribosomal domain is permitted for strains of a single biological species, rDNA sequence analysis being a simple and reliable tool for taxonomic identification.…”