Engineered Microbial Consortium for the Efficient Conversion of Biomass to Biofuels Page: 23
ix, 120 pages : illustrations (some color)View a full description of this dissertation.
Extracted Text
The following text was automatically extracted from the image on this page using optical character recognition software:
[95], a mobile group II intron originating from the Lactoccous lactis, the L1.LtrB intron, was used
to disrupt both the paralogous L-lactate dehydrogenase and L-malate dehydrogenase genes,
distinguishing the overlapping substrate specificities of these enzymes. Both mutations were then
combined into a single strain, resulting in a substantial shift in fermentation toward ethanol
production. This double mutant produced 8.5-times more ethanol than wild-type cells growing on
crystalline cellulose.
2.2 The Endoglucanases (celZ and celY) from Erwinia chrysanthemi
Erwinia chrysanthemi is a pathogenic enterobacterium, which causes soft-rot disease in
plants [96]. It secretes into the extracellular medium several enzymes, which allow it to digest the
plant cell walls [97]. CelY and CelZ proteins are two different glucanases from this
microorganism. With carboxymethyl cellulose (CMC) as a substrate, 95% of the total
endoglucanase activity was attributed to CelZ while only 5% of the activity attributed to CelY, but
synergy was observed when both enzymes were used on the substrate that resulted in an increase
in activity of 1.8-fold [98]. In another related study, genes celY and celZ from Erwinia
chrysanthemi were both functionally integrated into the chromosome of Klebsiella oxytoca P2
using surrogate promoters from Zymomonas mobilis for expression. This resulted in the secretion
into the extracellular milieu of more than 20,000 endoglucanase units (carboxymethyl cellulose
activity) per liter of fermentation broth [99]. Another strain of Klebsiella oxytoca M5A1
containing chromosomally integrated genes for ethanol production from Zymomonas mobilis and
endoglucanase genes from Erwinia chrysanthemi (celY, celZ) produced 20,000 U of
endoglucanase L-1 [100].23
Upcoming Pages
Here’s what’s next.
Search Inside
This dissertation can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Dissertation.
Anieto, Ugochukwu Obiakornobi. Engineered Microbial Consortium for the Efficient Conversion of Biomass to Biofuels, dissertation, August 2014; Denton, Texas. (https://digital.library.unt.edu/ark:/67531/metadc699973/m1/34/: accessed July 17, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; .