Carbohydrate metabolism of iron-rich and iron-poor Staphylococcus aureus.

Comparative studies were made of the metabolic activities of a strain of Staphylococcus 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 ) ; ironpoor without glucose (Fe G ) ; iron-rich with glucose (Fe + G + ) ; iron-poor with glucose (FeG + ) . Fe+ G cocci oxidized glucose, Land D-lactate, pyruvate, acetate, forrnate, and Krebs cycle intermediates to completion. Of these substrates, only glucose and the lactates were oxidized by the FeG organisms. These latter oxidations proceeded at decreased rates and incompletely to acetate and acetoin. Fe+ G + cocci in comparison with the Fe+ G cocci 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 FeG + 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 glycolysed glucose a t 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 yo that of Fe + G cocci.