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Physiological basis for meso-tartrate sensitivity in some strains of Salmonella typhimurium
Abstract:
meso-Tartrate inhibited the growth of non-meso-tartrate-utilizing strains of Salmonella typhimurium in peptone water media and mineral salts media with some, but not all, carbon sources. C-R intermediates of the tricarboxylic acid cycle or compounds readily converted to them and substrates metabolized independently of the C-6 part of the cycle spared bacteria from the inhibitory effects of meso-tartrate when added to cultures along with meso-tartrate. Experiments with cell-free extracts of non-meso-tartrate-utilizing strains from batch and continuous cultures showed that meso-tartrate was a competitive inhibitor of isocitrate dehydrogenase and isocitrate lyase activities and also inhibited citrate synthase and malate synthase activities. The synthesis of these enzymes was not inhibited by meso-tartrate. The isocitrate enzymes of meso-tartrate-utilizing strains of S. typhimurium were similarly inhibited by meso-tartrate, but inhibition of the growth of meso-tartrate-utilizing strains was demonstrable only in uninduced cultures in which the intracellular concentrations of meso-tartrate were high.
Insights
Meso-tartrate inhibits Salmonella typhimurium growth by interfering with key metabolic enzymes. However, certain carbon sources and intermediates of the tricarboxylic acid cycle can overcome this inhibition.
Area of Science:
- Microbiology
- Biochemistry
- Enzymology
Background:
- Meso-tartrate is a compound that can affect bacterial growth.
- Salmonella typhimurium is a bacterium with a well-characterized metabolic system.
- Understanding metabolic inhibition is crucial for controlling bacterial proliferation.
Purpose of the Study:
- To investigate the inhibitory effects of meso-tartrate on Salmonella typhimurium growth.
- To identify the specific enzymes and metabolic pathways affected by meso-tartrate.
- To determine the conditions under which meso-tartrate inhibition can be overcome.
Main Methods:
- Bacterial growth assays in various media with and without meso-tartrate.
- Enzyme activity measurements using cell-free extracts.
- Analysis of tricarboxylic acid cycle intermediates and related enzymes.
Main Results:
- Meso-tartrate inhibited the growth of non-meso-tartrate-utilizing Salmonella typhimurium strains.
- Growth inhibition was overcome by specific carbon sources and tricarboxylic acid cycle intermediates.
- Meso-tartrate competitively inhibited isocitrate dehydrogenase and isocitrate lyase, and also inhibited citrate synthase and malate synthase activities.
- Enzyme synthesis was not affected by meso-tartrate.
Conclusions:
- Meso-tartrate exerts its inhibitory effect on Salmonella typhimurium by targeting key enzymes in the tricarboxylic acid cycle.
- Metabolic context, including carbon source availability and intracellular intermediate concentrations, influences the impact of meso-tartrate.
- The study elucidates a specific mechanism of metabolic inhibition in bacteria.