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

Abstract

Surmmary 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 —); 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— 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 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 glycolysed 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.