Incorporation of Linoleate by a Halotolerant Yeast, Saccharomyces rouxii

Abstract

Oxygen absorption on linoleate by a halotolerant yeast, Saccharomyces rouxii IY-5 was examined with bovine serum albumin-linoleate complex. The maximum oxygen absorption was observed on the yeast cells harvested at the late log phase. At the initial stage of oxygen absorption on linoleate, it increased linearly with time or with cell concentration. From the incorporation assay of linoleate Km was 42.0μm and Vmax was 2.17nmole/mg min. Optimum pH of transport was 7.5. Examination by a Warburg manometer revealed that 1-¹⁴C-linoleate was degraded to ¹⁴CO₂, which was the indication of the linoleate oxygen absorption by S. rouxi IY-5. Oxygen absorption on linoleate was measured by Biooxygraph with an oxygen electrode. Optimum pH of oxygen absorption was 4.0, which was different from that of incorporation. From the data of the substrate specificity, the oxygen absorption was remarkably high on free acids and methylesters of linoleate and linolenate as substrates. Glucose did not work to stimulate the oxygen absorption on linoleate though it was even a better substrate than linoleate. The cells grown in the media with 1M NaCl Showed high oxygen absorption on linoleate in the same or lower concentration on NaCl; while the cells grown in 2M NaCl showed high oxygen absorption under 2M NaCl.