Production of astaxanthin at moderate temperature in using a two-step process.

In order to achieve continuous industrial production of astaxanthin in , a moderate temperature (25-37°C) fermentation process was needed. In this study, a two-step process with a 20°C pre-culture for 18 h and a 30°C culture for 30 h was performed to achieve the astaxanthin yields of 116.42 μg g dry cell weight, which was lower than that in the normal process (20°C, 96 h). However, cell yield (Y) and product yield (Y) showed no significant differences between the two processes, suggesting that moderate temperature did not affect the productivity of astaxanthin. The transcriptional levels of genes involved in astaxanthin synthesis were compared in different culture times and a negative correlation between temperature and expression of carotenogenic genes was found. This work provided a potential method for continuous production of astaxanthin using at moderate temperature throughout the year.