Effects of Ultra High-Pressure Treatment on the Red Yeast Strain RG-8

The effects of ultra high-pressure (UHP) on the growth and its ability of beta-carotene biosynthesis of Rhodotorula glutinis RG-8 were studied. After the treatments of 5 repeated cycles at 300 MPa for 15 min, the barotolerant mutant RG-8-9 was obtained from this strain. The survival ratio of the parent strain RG-8 was increased from 1.40times10^-3% after the treatment of first cycle to 1.47times10^-1% after the treatment of fifth cycle. The biomass of mutant RG-8-9 was 22.8 g/L after 72 h of culture, decreased by 2.6% compared with 23.4 g/L from the parent strain RG-8, but its beta-carotene production could reach 20.6 mg/L, increased by 63.5% compared with 12.6 mg/L from the parent strain RG-8. The genetic quality of mutant strain RG-8-9 was proved to be stable by experiments. The result of restriction fragment length polymorphism analysis suggested that mutant strain RG-8-9 was likely to change in nucleic acid level, and thus enhanced beta-carotene production should be a result of gene mutation induced by UHP.