K-097. Growth Properties of a thyX Deletion Mutant of Corynebacterium glutamicum ATCC 13032

M-J. Park, S-H. Cho, H-G. Rhie;
Kyunghee Univ., Seoul, REPUBLIC OF KOREA.

A search of the "Cluster of Orthologous Groups of proteins" (COG) database showed the presence of a gene homologous to an alternative thymidylate synthase, thyX, in Corynebacterium glutamicum ATCC 13032. The additional alternative thyX complemented thyA mutation in E. coli and was expressed in C. glutamicum in previous study. A functional knockout of the thyX gene was constructed by allelic replacement using a sucrose counter-selectable suicide plasmid and confirmed by PCR analysis. This mutant was viable without thymidine supplementation, supporting that thyX is not an essential gene in C. glutamicum. Both wild-type and mutant strains grew on rich and defined minimal media with similar growth rate at logarithmic growth phase. In contrast, when mutant strain at stationary growth phase was subcultured in the minimal medium, it exhibited longer lag phase than that of wild-type strain. These results suggest that ThyX may play role in either survival during nutritional starvation or growth recovery in new growth condition.