The complete genome sequence of Corynebacterium glutamicum strain R was determined to allow its comparative analysis with other corynebacteria. The biology of corynebacteria was explored by refining the definition of the subset of genes that constitutes the corynebacterial core as well as those characteristic of saprophytic and pathogenic ecological niches. In addition, the relative scarcity of corynebacterial sigma factors and the plasticity of their two-component system machinery reflect their relatively exacting nutritional requirements and reduced membrane-associated and secreted proteins. The conservation of key genes and pathways between corynebacteria, mycobacteria and Nocardia validates the use of C. glutamicum to study fundamental processes that are conserved in slow-growing mycobacteria, including pathogenesis-associated mechanisms. The discovery of 39 novel genes in C. glutamicum R that have not been previously reported in other corynebacteria supports the rationale for sequencing additional corynebacterial genomes to better define the corynebacterial pan-genome and identify previously undetected metabolic pathways in these organisms.

The effect of superoxide anion radicals on the photosynthetic electron transport chain was studied in leaves and isolated thylakoids from tobacco. Superoxide was generated by methylviologen (MV) in the light at the acceptor side of photosystem I (PSI). In isolated thylakoids, the largest damage was observed at the level of the water‐splitting activity in photosystem II (PSII), whereas PSI was hardly affected at the light intensities used. Addition of reactive oxygen scavengers protected PSII against damage. In leaves in the presence of MV, the quantum yield of PSII decreased during illumination whereas the size of the P₇₀₀ signal remained constant. There was no D1 protein loss in leaves illuminated in the presence of MV and lincomycin, but a modification to a slightly higher molecular mass was observed. These data show that PSII is more sensitive to superoxide or superoxide‐derived reactive oxygen species (ROS) than PSI. In our experiments, this susceptibility was not because of any action of the ROS on the translation of the D1 protein or on the repair cycle of photosystem.

Two whole-cell bioluminescent reporters were constructed by fusing the reporter genes luxAB with the Co2+ and Zn2+ inducible coaT promoter or the Ni2