Location: Bioenergy ResearchTitle: Cellobiose fermenting yeast produces varied forms of native ß-glucosidase Author
|Wang, Xu - Henan Agricultural University|
|Weber, Scott - Former ARS Employee|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/28/2017
Publication Date: 5/1/2017
Citation: Wang, X., Liu, Z.L., Weber, S. 2017. Cellobiose fermenting yeast produces varied forms of native ß-glucosidase [abstract]. For Symposium of Biotechnology for Fuels and Chemicals, May 1-4, 2017, San Francisco, California. M25.
Technical Abstract: The rapid growing yeast strain NRRL Y-50464 is robust to environmental stress and resistant to 2-furaldehyde (furfural) and 5-[hydroxymethyl]-2-furaldehyde (HMF). It is able to utilize cellobiose as its sole source of carbon and produces ethanol from lignocellulosic biomass by simultaneous saccharification and fermentation (SSF) without supplemental ß-glucosidase. Beta-glucosidase is a key member of cellulase enzyme complex that hydrolyzes glycosidic bonds from glycosides and oligosaccharides. Eliminating the need for external ß-glucosidase should directly reduce enzyme costs. Here, we characterize three native ß-glucosidases (BGL1, BGL2, and BGL3) of NRRL Y-50464. Specific activity of all three ß-glucosidases was intact in the presence of furfural and HMF. With a molecular weight ranging from 93 to 104 KD, these BGLs showed an optimum temperature from 45 to 55 deg C and optimum pH from 5 to 6. All forms of ß-glucosidase displayed a relatively stronger affinity toward cellobiose and higher levels of product inhibition against glucose with the highest Ki of 61.97 mM for BGL2. BGL2 was also tolerant to 16% ethanol, which was the highest of the three enzymes. Amino acid sequence analysis indicated a closer relatedness between BGL2 and BGL3 than for either with BGL1. These enzymes were active against at least 14 oligosaccharides associated with lignocellulosic hydrolysates used for ethanol production. Results of this study confirmed the cellobiose hydrolysis function of strain NRRL Y-50464 with a family of at least three ß-glucosidases.