Effect of hypobaric oxygen and oleic acid on respiration of Staphylococcus aureus

The effect of hypobaric oxygen, with oleic acid in the nutrient substrate, on respiration and slime production by a pulmonary isolate of Staphylococcus aureus was investigated. Under hypobaric, but not normal oxygen pressure, the addition of oleic acid to the nutrient broth caused the bacteria to drastically diminish their demand for oxygen and initiate the secretion of extrapolymeric substances (slime). The decrease in oxygen demand was found to result from impairment of the capacity to reduce and oxidize the coenzyme NAD. Prior to the initiation of slime production, the rate of oxidation exceeded the rate of reduction of the coenzyme, whereas with slime production the rate of reduction was greatest. This could result in elevation of the cellular NADH, which could stimulate gluconeogenesis and thereby increase the synthesis of the carbohydrate component of the slime. The results suggest that staphylococcal infections, such as those of the pulmonary tract in cystic fibrosis and essential fatty acid deficiency, may occur in response to a peculiar chemical environment.