Study on the effect of benomyl on the ability to enhance astaxanthin production of Rhodosporidium toruloides and evaluate the free radical scavenging activity ABTS of astaxanthin

Abstract

Astaxanthin is a xanthophyll carotenoid and it has economic value when it has been used as a colorant in food as well as when applied in medicine. This work aimed to attain Rhodosporidium toruloides mutants for enhanced astaxanthin accumulation using a benomyl agent. Benomyl treatment was shown to be efficient at different investigated concentrations for enhanced astaxanthin production of yeast. Among the screened mutants, B18 (1138.51 µg/l astaxanthin content) exhibited the highest astaxanthin production which was 3.1 times higher than that of the wild type. Mutant strain B18 consists of four phases including a lag phase of about 5 hours, 33 hours of log phase, 30 hours of stationary phase and a death phase after 63 hours of inoculation. The highest accumulated astaxanthin was 1138 µg/l after 96 hours of inoculation. The results showed that the scavenging capacity of 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) - ABTS free radicals from the crude extract of astaxanthin from mutant strain B18 with IC₅₀=8.531 µg/ml was 6.2 times higher than that of vitamin E.