ENERGY AND NITROGEN REQUIREMENTS OF MICROCOCCUS ROSEUS

Abstract

A collection of pink-pigmented micrococci has been studied and found to be a relatively homogeneous group that deserve species recognition as Micrococcus roseus. These organisms are salt-tolerant obligate aerobes that usually reduce nitrates and do not hydrolyze gelatin. They can utilize xylose, glucose, fructose, mannose, galactose, sucrose, acetate, pyruvate, lactate, malate, succinate, and gluconate as carbon and energy sources. Most strains also can utilize arabinose, lactose, maltose, glycerol, mannitol, sorbitol, and propionate. A synthetic basal medium has been devised that will give excellent growth of these organisms with glutamic acid as the sole source of nitrogen, carbon, and energy. Two vitamins, biotin and thiamine, are required by all strains, and are the only vitamins in the synthetic medium that was used to study interrelationships between nitrogen and carbon sources. Ammonia can serve as the sole source of nitrogen when glucose, or certain other substrates, is the sole source of carbon and energy. Not all substrates that can supply energy in a complex medium can do so in the synthetic medium with ammonia as the sole source of nitrogen. Some amino acids in addition to glutamate have a limited ability to serve as a source of both carbon and nitrogen. The ability of individual amino acids to serve as a sole source of nitrogen depends upon the nature of the substrate that is present as a carbon and energy source.