Functional expression of bacterial Zymobacter palmae pyruvate decarboxylase gene in Lactococcus lactis.
A pyruvate decarboxylase (PDC) gene from bacterial Zymobacter palmae (Zymopdc) was cloned, characterized, and introduced into Lactococcus lactis via a shuttle vector pAK80 as part of a research strategy to develop an efficient ethanol-producing lactic acid bacteria (LAB). The expression levels of Zymopdc gene in the host, as measured by a colorimetric assay based on PDC catalyzed formation of (R)-phenylacetylcarbinol ((R)-PAC), appeared to be dependent on the strength of corresponding Gram-positive promoters. A constitutive, highly expressed promoter conferred the greatest PDC activity, and an acid-inducible promoter demonstrated acid-inducible expression. The metabolic production of ethanol and other products was examined in flask fermentations. More than eightfold increases in acetaldehyde concentrations were detected in two recombinant strains. However, no detectable differences for ethanol fermentation in these engineered strains were observed compared with that of the strain carrying lacZ reporter.
Liu
Siqing
S
Bioproducts and Biocatalysis Research Unit, National Center for Agriculture Utilization Research, USDA, ARS, 1815 N. University St., Peoria, IL, 61604, USA. lius@ncaur.usda.gov
Dien
Bruce S
BS
Cotta
Michael A
MA
D001483:Base Sequence; D003001:Cloning, Molecular; D003124:Colorimetry; D000431:Ethanol / Q000378:metabolism; D005285:Fermentation; D015964:Gene Expression Regulation, Bacterial; D005818:Genetic Engineering / Q000379:methods; D044129:Halomonadaceae / Q000201:enzymology* / Q000235:genetics; D013294:Lactococcus lactis / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011767:Pyruvate Decarboxylase / Q000235:genetics* / Q000378:metabolism*; D011995:Recombination, Genetic
D000431:Ethanol; D011767:Pyruvate Decarboxylase