Characterization of a heat-shock process for reduction of the nucleic acid content of Candida utilis.

A process for reducing the nucleic acid content of Candida utilis NRRL Y900 has been developed. The optimal process consists of heating the cells suspended in spent medium initially at pH 4.0 for various times at three different temperatures. Initially a heat-shock at 68 C for 1 to 3 sec is performed followed by incubation for 1 hr at 45 to 50 C and for a 2nd hr at 52 to 55 C. The distribution of degradation products has been characterized. Initially 90% of the nucleic acids were in a polymerized form (extractable by hot perchloric acid). After 30 min, much of this material was hydrolyzed but remained within the cell (extractable by cold perchloric acid). After 2 hr, most of the hydrolysis products leaked into the surrounding medium with only a small amount of low-molecular-weight material remaining within the membrane. Predominantly 3'-mononucleotides accumulated within the cell and eventually leaked from the cell.