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Gas chromatographic determination of freeamino acids in samples withdrawn during lactic acid production ba Lactobacillus amylovorus DSM 20531T

In this work derivatization of amino- and carboxy groups of amino acids by ethyl-chloroformate in water solution was described. In this reaction N(O, S)- alkoxycarbonyl-alkyl esters have been synthesised in water phase and, subsequently, they have been extracted to organic phase - mixture of chloroform and ethylchloroformate. In samples prepared for analysis by optimized gas chromatographyc method, 15 out of 20 alkoxycarbonyl-alkyls derived from amino acids have been detected. This analytical method is precise, accurate, sensitive and robust and, therefore, it is appropriate for determination of concentration of amino acids in complex media which have been often used in research as well as in biotechnological production. By using the method it was proven that sterilization of water solutions of amino acids affects its concentration. In this particular case amino acids from meat extract, yeast extract and peptone - three compounds which are usually added to media as nitrogen sources, have been taken into account. Concentration of amino acids from samples whithdrawn during biotechnological batch production of lactic acid in a lab-scale strirred tank bioteactor has also been determined. Bioprocess for lactic acid production has been carried out by Lactobacillus amylovorus DSM 20531T. The lactic acid bacterium posse’s proteolytic and amylolytic activity, and it is good candidate for lactic acid production by simultaneous saccharification and fermentation. Results of this work will contribute to better understanding of physiology of bacteria which may be further adapted and applied in lactic acid production in highly efficient and sustainable bioprocess.

determination of amino acid concentration; gas chromatography; biotechnological production of lactic acid; lactic acid bacteria; Lactobacillus amylovorus

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