engleski

Reduction of CO2 emission in novel pyruvate bio-production process

The commercial demand for pyruvic acid is expanding because of its use as an effective starting material for the synthesis of many drugs, agrochemicals and nowadays in food industry as a fat burner. It is also a valuable substrate for the enzymatic production of amino acids such as L-tryptophane, L-tyrosine and L-dihydroxyphenylalanine (L-DOPA). In the classical chemical method pyruvate is produced by the dehydration and decarboxylation of tartaric acid in the presence of potassium hydrogen sulfates at 220° C. Also, decarboxylation of oxalo-acetic acid, hydrolysis of acylcyanids and oxidation of lactate, in the presence of heavy metals as catalysts and high temperatures, are common methods for pyruvate production. All processes described before are energy-intensive and environmental incompatible, therefore, in last two decades, development of environmental friendly and sustainable bioproduction pyruvate processes was intensify. The main goal in this work is development of a pyruvate bioproduction process from glucose with a high molar pyruvate/glucose yield (approaching 2 mol pyruvate/mol glucose) and space-time yield using a recombinant Escherichia coli YYC202 strain [1-3]. This strain is completely blocked in its ability to convert pyruvate in acetyl-CoA or acetate, resulting in acetate-auxotrophy during growth in glucose minimal medium. Evidence was obtained that high extra-cellular pyruvate concentration inhibits the process. To face this problem with process engineering means, repetitive fed-batch experiments with cell retention were performed. Molar yield pyruvate/glucose was improved up to 1.7 mol/mol. STY was increased more than 300 % and has reached 145 g/L/d. Continuous process with cell retention was developed to simplify complex set-up used for repetitive fed-batch process. At optimal process conditions molar yield of 1.24 mol pyruvate/mol glucose and STY higher than 110 g/L/d were achieved. Additionally, CO2 emission calculated per tone of pyruvate produced, in repetitive fed-batch process, was decreased three fold in comparison to CO2 emission in classical chemical method for pyruvate production.

Escherichia coli; bio-production; pyruvate; process development

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