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Unmarked insertional inactivation in the gfo gene improves growth and ethanol production by Zymomonas mobilis ZM4 in sucrose without formation of sorbitol as a by-product, but yields opposite effects in high glucose

Paper ID Volume ID Publish Year Pages File Format Full-Text
3368 166 2013 9 PDF Available
Title
Unmarked insertional inactivation in the gfo gene improves growth and ethanol production by Zymomonas mobilis ZM4 in sucrose without formation of sorbitol as a by-product, but yields opposite effects in high glucose
Abstract

Sorbitol, one of the main by-products of growth on high sucrose concentrations, is catalyzed by glucose-fructose oxidoreductase (GFOR, EC 1.1.99.28) in Zymomonas mobilis, which decreases the ethanol yield. In this study, an unmarked gfo mutant from Z. mobilis ZM4 was constructed using a site-specific FLP recombinase, and growth and ethanol production were evaluated with or without the addition of sorbitol to the media. The inactivation of gfo had contrasting effects in different substrates, especially at high concentrations. The maximum specific growth rate (μm) and theoretical ethanol yield value (Ym) increased from 0.065 h−1 and 60.56% to 0.094 h−1 and 83.87% in 342 g/L sucrose, respectively. Conversely, in 200 g/L glucose, gfo inactivation decreased μm and Ym from 0.15 h−1 and 89.85% to 0.10 h−1 and 67.59%, respectively, and prolonged the lag period from 16 h to 40 h. The addition of sorbitol slightly accelerated growth and sucrose hydrolysis by the gfo mutant in 342 g/L sucrose; however, addition of sorbitol restored the μm and Ym of the gfo mutant in 200 g/L glucose to 0.14 h−1 and 82.50%, respectively. Inactivation of gfo had a small effect on fructose utilization, and a positive one on mixture of glucose and fructose similar to that on sucrose. These results provide further understanding of the osmoregulation mechanisms in Z. mobilis and may help to exploit the biotechnological applications of this industrially important bacterium.

► An unmarked gfo mutant from Zymomonas mobilis ZM4 was constructed. ► gfo inactivation improved growth and ethanol production in 1 M (342 g/L) sucrose. ► gfo inactivation impaired growth and ethanol production in 1.11 M (200 g/L) glucose. ► Sorbitol accelerated growth and sucrose hydrolysis by the mutant in 1 M sucrose. ► Sorbitol restored growth and ethanol production by the mutant in 1.11 M glucose.

Keywords
Zymomonas mobilis; Glucose-fructose oxidoreductase inactivation; Sucrose; Glucose; Growth; Ethanol production
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Unmarked insertional inactivation in the gfo gene improves growth and ethanol production by Zymomonas mobilis ZM4 in sucrose without formation of sorbitol as a by-product, but yields opposite effects in high glucose
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Publisher
Database: Elsevier - ScienceDirect
Journal: Biochemical Engineering Journal - Volume 72, 15 March 2013, Pages 61–69
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us