Measurement of extracellular metabolites

Version 1

SysMO is a European transnational funding and research initiative on "Systems Biology of Microorganisms".

The goal pursued by SysMO was to record and describe the dynamic molecular processes going on in unicellular microorganisms in a comprehensive way and to present these processes in the form of computerized mathematical models.

Systems biology will raise biomedical and biotechnological research to a new quality level and contribute markedly to progress in understanding. Pooling European research ...

"Systems Understanding of Microbial Oxygen responses" (SUMO) investigates how Escherichia coli senses oxygen, or the associated changes in oxidation/reduction balance, via the Fnr and ArcA proteins, how these systems interact with other regulatory systems, and how the redox response of an E. coli population is generated from the responses of single cells. There are five sub-projects to determine system properties and behaviour and three sub-projects to employ different and complementary modelling ...

The electron transport chain of E. coli is branched. Different NAD Dehydrogenases and terminal oxidases are known to be expressed at different oxygen availabilities. By deleting multiple genes mutant strains were constructed that posses a linear electron transport chain. These mutants were investigated in continous bioreactor experiments with limiting glucose and varying oxygen supply.

In Escherichia coli several systems are known to transport glucose into the cytoplasm. A series of mutant strains were constructed, which lack one or more of these uptake systems. These were analyzed in aerobic and anaerobic batch cultures, as well as glucose limited continuous cultivations.

Changing the oxygen availability leads to an adaptation of Escherichia coli at different biological levels. After pertubation of oxygen in chemostat experiments the microorganism(s) will come back to another steady state. This investigation deals with these stationary responses of Escherichia coli within the aerobiosis scale. The change for different biological variables, in different areas of the organism like the electron transport chain, the TCA cycle or globally is investigated by wildtype ...

A set of isogenic mutant strains was constructed which lack NADH Dehydrogenase I as well as two terminal oxidases, resulting in strains with linear respiratory chain. The different strains hence differ in the terminal oxidase and express either cytochrome bo, cytochrome bdI or cytochrome bdII. The different strains were cultivated in glucose-limited chemostats with defined low levels of oxygen supply. Biomass and by-product formation, gene expression and the phosphorylation state of the important ...

Mutant strains in which one or more of the potential glucose uptake systems was deleted have been analyzed in aerobic and anaerobic batch cultures, as well as aerobic chemostat cultures.

Mutant strains which carry deletions of important metabolic enzymes, as well as mutant strains with altered regulation, need to adapt by changing fluxes or gene expression to compensate with the absence/differed concentration of these key enzymes. This may give new insights in the regulation of these pathways/enzymes.

This document describes by-product formation rates measured in MG1655 at steady-state conditions in Infors-Multifors-Bioreactors.

E. coli MG1655 and ∆sdhC and ∆frdA isogenic mutant strains were characterized in batch growth curves aerobic and anaerobically. Optical density, glucose consumption and by-product accumulation were measured during growth.

Glucose transporter mutants were analyzed under aerobic and aerobic conditions in batch cultures with glucose as substrate. Acetate formation rates and glucose consumption rates were measured, as well as extracellular cAMP concentrations.

Mutants with a linear respiratory chain consisting of NADH Dehydrogenase II and one of the terminal oxidases cytochrom bo, cytochrome bd I or cytochrome bd II were growth in chemostats with defined oxygen supply. The amounts of biomass formed and of acetate and formate produced were determined.