Corynebacterium glutamicum and Brevibacterium are of great importance to the fermentation industry. They have potential for application in foreign protein expression. This research has been focused mainly on strain improvement and development of technique to overcome the barriers that effect successful introduction of foreign DNA into these corynebacteria. Corynebacterial cell wall structures, which include corynemycolic acids, act as a physical barrier for DNA transformation into the cell. The research reported in this thesis focuses mainly on understanding the nature of
physical barrier including, firstly, determining the effect of growth medium containing glycine and INH on the mycolic acids and fatty acids composition of cell wall and compare this with the whole cell mycolates of wild-type and mutants of C. glutamicum. Secondly, investigating the genetics of mycolic acids biosynthesis. This involved identification of
presumptive inhA gene involved in mycotic acid synthesis using various molecular biology approaches in C. glutamicum and Brevibacterium species, sequencing the inhA gene in
several corynebacteria strains and defining any genetic changes, which may have occurred in INH-hypersensitive mutants through sequence analysis of the InhA protein in
mutants in comparison the sequence, determined for the wild type C. glutamicum. Thirdly, to determine the function of presumptive inhA gene in corynebacteria by inactivation
using homologous recombination and analysis of the resulting mutants to deduce correlation between genetic and physiological changes.