Global Gene Expression Differences Associated with Changes in Glycolytic Flux and Growth Rate in Escherichia coli during the Fermentation of Glucose and Xylose

摘要: The simplicity of the fermentation process (anaerobic with pH, temperature, and agitation control) in ethanologenic Escherichia coli KO11 LY01 makes this an attractive system to investigate utility gene arrays for biotechnology applications. By using system, expression, glycolytic flux, growth rate have been compared glucose-grown xylose-grown cells. Although initial metabolic steps differ, ethanol yields from both sugars were essentially identical on a weight basis, little carbon was diverted biosynthesis. Expression only 27 genes changed by more than 2-fold strains. These included induction xylose-specific operons (xylE, xylFGHR, xylAB) regulated XylR cyclic AMP-CRP repression Mlc-regulated encoding glucose uptake (ptsHIcrr, ptsG) mannose (manXYZ) during xylose. However, expression central metabolism biosynthesis differed less 2-fold. Simple statistical methods used these subtle changes. reproducibility (coefficient variation 12%) measurements (mRNA as cDNA) found be similar that typically observed vitro enzyme activities. Using Student's t test, many smaller but significant sugar-dependent changes identified (p < 0.05 strains). A total 276 highly expressed xylose; 307 glucose. Slower (lower ATP yield) xylose accompanied decreased 62 concerned small molecules (amino acids, nucleotides, cofactors, lipids), transcription, translation; 5 such at higher level. In cells, 90 associated transport, catabolism, regulation pathways alternative sources levels consistent relaxation control regulatory system. Changes Embden-Meyerhof-Parnas (EMP) pathway excellent agreement calculated flux individual metabolites. Flux through all one step, pyruvate kinase, predicted fermentation. (glucose/xylose) cells EMP except isoenzymes kinase (pykA pykF). generally statistically strains pykF isoenzyme activated fructose-6-phosphate, key metabolite connecting pentose pathway. coordinated suggest presence common within may broadly distributed. contrast, Pentose-Phosphate did not differ significantly between