AN INVERTASE WITH UNUSUAL PROPERTIES SECRETED BY SUCROSE-GROWN CELLS OF CORYNEBACTERIUM-MURISEPTICUM

The mode of sucrose utilisation by Corynebacterium murisepticum cells growing on M9 minimal medium supplemented with 0.4% sucrose as the car bon source was studied. It was observed that during growth of this org anism, sucrose in the medium is hydrolysed to glucose and fructose, su ggesting the formation of an extracellular invertase. Unlike in other microorganisms (e.g. Saccharomyces cerevisiae) the invertase formation is not repressed by the presence of glucose in the medium. The invert ase was found to be the onlY predominant extracellular protein in the culture broth and could be purified in a single step by precipitation at 90% ammonium sulphate saturation. The purified protein had a molecu lar mass of 70,000 daltons. It not only showed invertase activity, but also a fructosyltransferase activity as it could convert sucrose to b eta-1,2-difructose, as well as to glucose and fructose.