Fed-batch bioprocess development for astaxanthin production by Xanthophyllomyces dendrorhous based on the utilization of Prosopis sp. pods extract

Abstract

This work focuses on using renewable sources as feedstock for the microbial production of carotenoids, valuable compounds for various industries. Xanthophyllomyces dendrorhous, which mainly synthesize astaxanthin and β-carotene, was used for the process. We proposed two strategies to achieve high production yields, the correct oxygen supply to the medium and the adoption of a fed-batch mode. Two factors related to the medium's oxygen transfer at a flask scale (working volume and agitation) were evaluated. Astaxanthin production was successfully correlated with the oxygen transfer coefficient (kLa) using a mesquite pods-based medium (MEM) and a chemically defined one (YM). kLa correlations were then used to set the conditions at a reactor scale. An optimum kLa of 16.86 h−1 was adequate to promote astaxanthin production in MEM (1824.13 μg/L). Meanwhile, in YM, optimum production (1656.24 μg/L) was obtained at the highest evaluated levels (17.77 h−1). Thus, a higher oxygen transfer rate is required to produce carotenoids in YM compared with MEM. Astaxanthin production was thus evaluated using a fed-batch process at flask and reactor scales. Reached production levels with fed-batch cultivation were 4465.12 μg/L (flask) and 4130.23 μg/L (reactor). This study demonstrated the correlation between oxygen transfer and carotenoids' production and the potential utilization of mesquite feedstock in a fed-batch bioprocess to improve carotenoids' yield by X. dendrorhous.