Ethanol production from cellobiose by Zymobacter palmae carrying the Ruminocuccus albus beta-glucosidase gene.
Its metabolic characteristics suggest Zymobacter palmae gen. nov., sp. nov. could serve as a useful new ethanol-fermenting bacterium, but its biotechnological exploitation would require certain genetic improvements. We therefore established a method for transforming Z. palmae using the broad-host vector plasmids pRK290, pMFY31 and pMFY40 as a source of transforming DNA. Using electroporation, the frequency of transformation was 10(5) to 10(6) transformants/mug of DNA. To confer the ability to ferment cellobiose, which is a hydrolysis product from cellulosic materials treated enzymatically or with acid, the beta-glucosidase gene from Ruminococcus albus was introduced into Z. palmae, where its expression was driven by its endogenous promoter. About 56% of the enzyme expressed was localized on the cell-surface or in the periplasm. The recombinant Z. palmae could ferment 2% cellobiose to ethanol, producing 95% of the theoretical yield with no accumulation of organic acids as metabolic by-products. Thus, expression of beta-glucosidase in Z. palmae expanded the substrate spectrum of the strain, enabling ethanol production from cellulosic materials.
Yanase
Hideshi
H
Department of Biotechnology, Faculty of Engineering, Tottori University, 4-101 Koyamacho-Minami, Tottori 680-8552, Japan. yanase@bio.rottori-u.ac.jp
Yamamoto
Keiko
K
Sato
Dai
D
Okamoto
Kenji
K
D002475:Cellobiose / Q000378:metabolism*; D000431:Ethanol / Q000378:metabolism*; D020563:Gammaproteobacteria / Q000201:enzymology* / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D015202:Protein Engineering / Q000379:methods*; D011994:Recombinant Proteins / Q000378:metabolism; D045857:Ruminococcus / Q000201:enzymology* / Q000235:genetics; D014169:Transformation, Bacterial / Q000502:physiology; D001617:beta-Glucosidase / Q000235:genetics / Q000378:metabolism*
D011994:Recombinant Proteins; D002475:Cellobiose; D000431:Ethanol; D001617:beta-Glucosidase