Acta Univ Latv (2005) 691: 83–91

The effect of stringent control on valine biosynthesis by Corynebacterium glutamicum

Abstract

The present study focused on methods of stringent response induction and the investigations of its effect on valine synthesis by the isoleucine auxotroph Corynebacterium glutamicum 13032 ΔilvA pJC1ilvBNCD. The intracellular concentration of guanosine tetraphosphate increased and bacterial growth rate decreased, i.e. intracellular stringent response, was induced under conditions of (i) cell culture growth in medium lacking isoleucine and (ii) reduced isoleucine uptake by cells. The induction of the cellular stringent response was followed by an increase in the activity of acetoxydroxy acid synthase, e.g. ilvBN-encoded key enzyme of valine synthesis, and by a drastic increase in the cell specific rate of amino acid synthesis. It was demonstrated that induction of the stringent response can be used as method to increase valine overproduction by C. glutamicum cells.