Carbon metabolism in Sulfobacillus thermosulfidooxidans subsp asporogenes,strain 41

The activities of carbon metabolism enzymes were determined in cellular ext racts of the moderately thermophilic, chemolithotrophic, acidophilic bacter ium Sulfobacillus thermosulfidooxidans subsp. asporogenes, strain 41, grown either at an atmospheric content of CO2 in the gas phase (autotrophically, heterotrophically, or mixotrophically) or autotrophically at a CO2 content increased to 5-10%. Regardless of the growth conditions, all TCA cycle enz ymes (except for 2-oxoglutarate dehydrogenase), one glyoxylate bypass enzym e (malate synthase), and some carboxylases (ribulose bisphosphate carboxyla se, pyruvate carboxylase, and phosphoenolpyruvate carboxylase) were detecte d in the cell-free extracts of strain 41. During autotrophic cultivation of strains 41 and 1269, the increase in the CO2 content of the supplied air t o 5-10% resulted in the activation of growth and iron oxidation, a 20-30% i ncrease in the cellular content of protein, enhanced activity of the key TC A enzymes (citrate synthase and aconitase), and, in strain 41, a decrease i n the activity of carboxylases.