Combined mutagenesis of Rhodosporidium toruloides for improved production of carotenoids and lipids.

Objective: To improve production of lipids and carotenoids by the oleaginous yeast Rhodosporidium toruloides by screening mutant strains.

Results: Upon physical mutagenesis of the haploid strain R. toruloides np11 with an atmospheric and room temperature plasma method followed by chemical mutagenesis with nitrosoguanidine, a mutant strain, R. toruloides XR-2, formed dark-red colonies on a screening plate. When cultivated in nitrogen-limited media, XR-2 cells grew slower but accumulated 0.23 g lipids/g cell dry wt and 0.75 mg carotenoids/g CDW. To improve its production capacity, different amino acids and vitamins were supplemented. p-Aminobenzoic acid and tryptophan had beneficial effects on cell growth. When cultivated in nitrogen-limited media in the presence of selected vitamins, XR-2 accumulated 0.41 g lipids/g CDW and 0.69 mg carotenoids/g CDW.

Conclusions: A mutant R. toruloides strain with improved production profiles for lipids and carotenoids was obtained, indicating its potential to use combined mutagenesis for a more productive phenotype.