Carbon isotopic fractionation in heterotrophic microbial metabolism. |
| |
| Authors: | N Blair A Leu E Muoz J Olsen E Kwong and D Des Marais |
| |
| Affiliation: | N Blair, A Leu, E Muñoz, J Olsen, E Kwong, and D Des Marais |
| |
| Abstract: | Differences in the natural-abundance carbon stable isotopic compositions between products from aerobic cultures of Escherichia coli K-12 were measured. Respired CO2 was 3.4% depleted in 13C relative to the glucose used as the carbon source, whereas the acetate was 12.3% enriched in 13C. The acetate 13C enrichment was solely in the carboxyl group. Even though the total cellular carbon was only 0.6% depleted in 13C, intracellular components exhibited a significant isotopic heterogeneity. The protein and lipid fractions were -1.1 and -2.7%, respectively. Aspartic and glutamic acids were -1.6 and +2.7%, respectively, yet citrate was isotopically identical to the glucose. Probable sites of carbon isotopic fractionation include the enzyme, phosphotransacetylase, and the Krebs cycle. |
| |
| Keywords: | |
|
|
