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Effect of alteration of the acetic acid synthesis pathway on the fermentation pattern of escherichia coli
Author(s) -
DiazRicci J. C.,
Regan L.,
Bailey J. E.
Publication year - 1991
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.260381109
Subject(s) - zymomonas mobilis , acetate kinase , pyruvate decarboxylase , biochemistry , fermentation , mutant , operon , pep group translocation , escherichia coli , pyruvic acid , acetic acid , alcohol dehydrogenase , plasmid , biology , chemistry , lactic acid , mixed acid fermentation , bacteria , ethanol , lactic acid fermentation , ethanol fuel , dna , genetics , gene
The glucose metabolism of an Escherichia coli strain bearing mutations abolishing both acetyl phosphotransferase (PTA) and acetate kinase (ACK) activities was studied under aerobic and anaerobic conditions. These studies were conducted in a complex medium with the mutant carrying no plasmid, the mutant carrying the common cloning vector pUC19, and the mutant carrying a plasmid bearing the “ pet ” operon that encodes Zymomonas mobilis pyruvate decarboxylase and alcohol dehydrogenase activities. The mutant carrying no plasmid showed lower specific growth and glucose uptake rates relative to the parent wild‐type strain (K‐12), Lactic acid was produced at higher levels than the wild type, and considerable amounts of pyruvic acid were secreted as an unusual byproduct. Analysis of other fermentation products showed low but significant amounts of acetic acid, no accumulation of formic acid, and lower secretion of succinate and ethanol. The maintenance of the plasmid pUC19 in the mutant negatively affected metabolism. Expression of the pet operon overcame the metabolic stress caused by the plasmid, enhancing growth and glucose uptake rates to the values observed in the plasmidfree mutant. Also, expression of the pet operon allowed consumption of pyruvate accumulated during the first hours of fermentation.