engleski

Development of environmental friendly and sustainable bio-production pyruvate 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 project 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]. 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. Due to the strain genotype, acetate availability was assumed to represent a key fermentation variable. Experimental studies identified a &#8216 ; ; ; ; simple&#8217 ; ; ; ; correlation between acetate consumption rate (ACR) and CO2 production rate (CTR), interestingly, with an optimum equal molar ratio. Therefore, CTR (calculated on-line by CO2 and O2 exhaust gas analysis) was used for on-line calculation and regulation of the acetate feed (acetate limiting, saturating and accumulating conditions could be established) [2]. Additionally glucose concentrations were controlled on-line. By controlling acetate and glucose, a series of lab-scale experiments were performed to optimize the molar yield of pyruvate/glucose, the space &#8211 ; ; ; ; time yield and final pyruvate concentration. At optimal process conditions, a final pyruvate concentration higher than 500 mM, a space-time yield of 24.7 mmol/L/h and a molar yield pyruvate/glucose of 0.80 mol/mol were achieved. [1] Bott, M., Gerharz, T., Takors, R., Zelic, B. (2001) Verfahren zur fermentativen Herstellung von Pyruvat, Detsche Patentanmeldung 101 29 711.4 [2] Gerharz, T., Zelic, B., Takors, R., Bott, M. (2001) Produktion von Pyruvat aus Glucose mit Escherichia coli. In: Biokatalyse, Ed. Heiden S., Erb, R., Spektrum Akademischer Verlag, 29-33

E. coli; process development; pyruvate; bio-production

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