Optimised Production and Extraction of Astaxanthin from the Yeast Xanthophyllomyces dendrorhous.

Zuharlida Tuan Harith,Micael De Andrade Lima,Dimitris Charalampopoulos,Afroditi Chatzifragkou

doi:10.3390/microorganisms8030430

Abstract

Currently, astaxanthin demand is fulfilled by chemical synthesis using petroleum-based feedstocks. As such, alternative pathways of natural astaxanthin production attracts much research interest. This study aimed at optimising bioreactor operation parameters for astaxanthin production and evaluating strategies for its subsequent extraction. The effect of pH and agitation was evident, as a significant reduction in both biomass and astaxanthin production was observed when the culture pH was not controlled and a low agitation speed was applied. At controlled pH conditions and a high agitation speed, a significant increase in biomass (16.4 g/L) and astaxanthin production (3.6 mg/L) was obtained. Enzymatic yeast cell lysis using two commercial enzymes (Accellerase 1500 and Glucanex) was optimised using the central composite design of experiment (DoE). Accellerase 1500 led to mild cell disruption and only 9% (w/w) astaxanthin extraction. However, Glucanex treatment resulted in complete astaxanthin extractability, compared to standard extraction method (DMSO/acetone). When supercritical CO2 was employed as an extraction solvent in Accellerase-pre-treated Xanthophyllomyces dendrorhous cells, astaxanthin extraction increased 2.5-fold. Overall, the study showed that extraction conditions can be tailored towards targeted pigments present in complex mixtures, such as in microbial cells.

Highlights

Astaxanthin has numerous applications in various sectors, including food, feed, and nutraceutical industries, as a pigment that possesses high antioxidant capacity [1]
High astaxanthin yields and productivities that have been associated with strains of X. dendrorhous, render this microorganism a promising choice for the potential scaling up and commercialisation of astaxanthin production [3,4,5], while its extraction and purification still contributes to the overall complexity and cost of the whole production process
This study aimed to investigate the production of astaxanthin in Xanthophyllomyces dendrorhous DSMZ 5626, using semi-defined media to optimise the fermentation parameters in lab-scale bioreactor cultures

Summary

Introduction

Astaxanthin has numerous applications in various sectors, including food, feed, and nutraceutical industries, as a pigment that possesses high antioxidant capacity [1]. In applications such as animal feed, whole microbial cells can be formulated as a feed ingredient without the need for pigment extraction. For more bespoke applications, such as cosmetic products and as food ingredients, pigment extraction is necessary to allow further purification processes to take place. High astaxanthin yields and productivities that have been associated with strains of X. dendrorhous, render this microorganism a promising choice for the potential scaling up and commercialisation of astaxanthin production [3,4,5], while its extraction and purification still contributes to the overall complexity and cost of the whole production process

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Conclusion