Characterization of a Heat-Shock Process for Reduction of the Nucleic Acid Content of Candida utilis

Abstract

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 p H 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.