Carbohydrate Metabolism of Iron-Rich and Iron-Poor Staphylococcus aureus

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Abstract
Comparative studies were made of the metabolic activities of a strain of aureus grown in iron-poor and iron-rich trypticase medium, with and without glucose. Four nutritionally distinctive types of organisms were produced: iron-rich without glucose (Fe + G-); iron-poor without glucose (Fe- G-); iron-rich with glucose (Fe + G +); iron-poor with glucose (Fe- G+). Fe+G- cocci oxidized glucose, L- and D-lactate, pyruvate, acetate, formate, and Krebs cycle intermediates to completion. Of these substrates, only glucose and the lactates were oxidized by the Fe- G-organisms. These latter oxidations proceeded at decreased rates and incompletely to acetate and acetoin. Fe+ G+ cocci in comparison with the Fe+ G- oocci showed glucose inhibition of oxidative capacity by metabolizing only glucose, L-lactate and pyruvate to acetate and failing to oxidize D-lactate, acetate and Krebs cycle intermediates. The Fe -G+ cocci showed the most severe restriction of oxidative capacity by oxidizing only glucose with the accumulation of much lactate and minor amounts of pyruvate, acetate and acetoin. The Fe- G-, Fe- G + , and Fe+ G+ cocci glycolyzed glucose at comparable rates, while the highly oxidative form Fe + G- showed a markedly decreased glycolytic activity. The catalase activity of both types of iron-poor cocci was very much lower than that of the iron-rich organisms. Of the latter, the Fe + G+ cocci showed a catalase activity only 20% that of Fe + G- cocci.