Enhancement of the astaxanthin production by culture conditions and mutagenesis in Paracoccus haeundaensis

Abstract

Astaxanthin represents a group of valuable molecules for pharmaceuticals, food and feed industries. In order to enhance the production of astaxanthin in Paracoccus haeundaensis, we have used various culture conditions using carbon/nitrogen sources and hydrogen peroxide. When carbon sources (lactose, fructose, glucose and mannitol) and nitrogen sources (sodium nitrate and potassium nitrate) were used, the production of astaxanthin was increased. The optimal C/N ratio was 3% carbon and 1% nitrogen and the astaxanthin production was 1.5 folds increased (641.17μg/g to 973.12μg/g dry cell weight (DCW)). The hydrogen peroxide was 1%, the product of astaxanthin was the highest. When H2O2 and C/N sources were the simultaneous added, the production of astaxanthin was increased approximately 1.83 folds (1019.16μg/g DCW). Cultures of Paracoccus haeundaensis were exposed to mutagens such as UV and ethylmethanesulfonate (EMS). The results showed that the survival rate decreased with the increase in UV exposure time and increase in EMS concentration. The hyper‐production mutant of astaxanthin was produced by UV irradiation (20 min exposure) with EMS treatment (0.4 M concentration). The isolated mutants exhibited an increase of 3.82 folds in astaxanthin production compared to the untreated initial strain. This genetically stable mutant strain may be a suitable candidate for the industrial production of astaxanthin.