hrvatski

Catabolism of Amino Acids in the Cells of Lactic Acid Bacteria

Lactic acid bacteria are auxotrophic industrial microorganisms usually cultivated in complex growth media. Among other ingredients, in the media for cultivation of the bacteria, particular amino acids need to be added. Branched-chain amino acids, leucine, isoleucine and valine, have to be added in the media in which lactic acid bacteria are expected to grow. Requirement for the rest of amino acids depends on the species and strain of the bacteria that have been used in defi ned bioprocess. During transport of amino acids in the lactic acid bacteria cells and degradation of this nitrogen and carbon sources, electrochemical gradient is formed, metabolic energy is yielded, enzyme cofactors are regenerated, effect of produced lactic acid i.e. reduction of pH value is moderated, the cells are adapted to osmotic shock as well as to stationary growth phase conditions. Amino acids and/or (intermediate) compounds generated during their catabolism represent precursors for production of: other aminoacids and fatty acids, which can be incorporated in membranes ; α-keto acids and α-hydroxy acids, which can also act as siderophores ; lactones ; nucleic acids ; lypides and polyamines. Amino acids catabolism in lactic acid bacteria cells is not known enough and it is mainly investigated in order to reduce concentration of undesired amines in fermented food.

amino acids; lactic acid bacteria; catabolism; metabolic energy-yielding; regulation of pH value; cofactor reoxidation; osmotic shock

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