CO2 Supplementation Does not Correct the "Interrupted" Growth Phenotype of a pduA Mutant Strain

       In both cyanobacteria and chemoautotrophs it has been demonstrated that

mutations in genes required for carboxysome formation result in a high-carbon dioxide requiring (HCR) phenotype (Friedberg et al. 1989, Kaplan et al. 1991, Badger and Price 1992, Marco et al. 1994, English et al. 1995, Ohkawa et al. 1998). To determine if highC02 supplementation would correct the "interrupted" growth phenotype observed in strain BE 182 (zlpduA); growth of both the wild type strain and BE 182 in the presence of 500 C02, with and without amino acid supplementation (VILT) (Figures 3-8 and 3-9) was examined. Either with or without C02, both the wild type strain and BE 182 grew similarly except for the aforementioned period of "interrupted" growth observed in BE 182 (Figures 3-8 and 3-9). These results indicate that high C02 supplementation appeared to have a general growth stimulation effect in the absence of VILT but did not significantly alter the interrupted growth observed in strain BE 182, hence CO2 does not appear to be involved in the function of the polyhedral organelles. Effects of PD Concentration on the Growth Rates of Wild Type and pduA Mutant Strains

      The effects of PD concentration on the growth of the wild type and a strain

containing a nonpolarpduA deletion mutation (BE182) were examined (Figure 3-10). At PD concentrations of 0.0% and 0.050%, the wild type strain and BE182 grew similarly. The generation times of the wild type were 10.8 and 11.9 h, respectively; whereas, the generation times of BE182 (zlpduA) were 11.7 and 10.7 h, respectively. At higher PD concentrations, some distinct differences between the wild type and strain BE182 were noted. At PD concentrations of 0.2%o and 0.400, the wild type strain grew with generation