Astaxanthin overproduction in yeast by strain engineering and new gene target uncovering

Abstract

BackgroundAstaxanthin is a natural carotenoid pigment with tremendous antioxidant activity and great commercial value. Microbial production of astaxanthin via metabolic engineering has become a promising alternative. Although great efforts have been conducted by tuning the heterologous modules and precursor pools, the astaxanthin yields in these non-carotenogenic microorganisms were still unsatisfactory for commercialization, indicating that in addition to targeted tailoring limited targets guided by rationally metabolic design, combining more globe disturbances in astaxanthin biosynthesis system and uncovering new molecular mechanisms seem to be much more crucial for further development. Since combined metabolic engineering with mutagenesis by screening is a powerful tool to achieve more global variations and even uncover more molecular targets, this study would apply a comprehensive approach integrating heterologous module engineering and mutagenesis by atmospheric and room temperature plasma (ARTP) to promote astaxanthin production in Saccharomyces cerevisiae.ResultsHere, compared to the strain with β-carotene hydroxylase (CrtZ) from Alcaligenes sp. strain PC-1, involving new CrtZ from Agrobacterium aurantiacum enhanced astaxanthin yield to 1.78-fold and increased astaxanthin ratio to 88.7% (from 66.6%). Astaxanthin yield was further increased by 0.83-fold (to 10.1 mg/g DCW) via ARTP mutagenesis, which is the highest reported yield at shake-flask level in yeast so far. Three underlying molecular targets (CSS1, YBR012W-B and DAN4) associated with astaxanthin biosynthesis were first uncovered by comparative genomics analysis. To be noted, individual deletion of CSS1 can recover 75.6% improvement on astaxanthin yield achieved by ARTP mutagenesis, indicating CSS1 was a very promising molecular target for further development. Eventually, 217.9 mg/L astaxanthin (astaxanthin ratio was 89.4% and astaxanthin yield was up to 13.8 mg/g DCW) was obtained in 5-L fermenter without any addition of inducers.ConclusionsThrough integrating rational engineering of pathway modules and random mutagenesis of hosts efficiently, our report stepwise promoted astaxanthin yield to achieve the highest reported one in yeast so far. This work not only breaks the upper ceiling of astaxanthin production in yeast, but also fulfills the underlying molecular targets pools with regard to isoprenoid microbial overproductions.Electronic supplementary materialThe online version of this article (10.1186/s13068-018-1227-4) contains supplementary material, which is available to authorized users.

The Astaxanthin Aggregation Pattern Greatly Influences Its Antioxidant Activity: A Comparative Study in Caco-2 Cells

“…[3,4], showed better antioxidant activity. Despite its poor stability and water solubility, natural AST has gained lots of attention due to its excellent antioxidant, anti-inflammatory, immunomodulatory, photoprotection, neuroprotection and tumor inhibition activities [5]. To improve the stability and the bioavailability of AST, many strategies have been employed to encapsulate AST.…”

In vitro and in vivo recombination of heterologous modules for improving biosynthesis of astaxanthin in yeast

“…According to the previous studies in our lab, combination of crtZ from Agrobacterium aurantiacum (Aa crtZ) and crtW from Brevundimonas vesicularis DC263 (B. DC263 crtW) has a positive impact on the astaxanthin pathway in yeast [19,20]. Thus, Aa crtZ and B. DC263 crtW were chosen to construct the initial astaxanthin-producing strain.…”

“…Modifying microbial cells to improve the production of the desired endogenous or exogenous metabolites is a broad aim at many areas of academic, industrial biotechnology and biosciences [8][9][10][11]. In recent years, the heterologous biosynthesis of astaxanthin has been successfully achieved in Escherichia coli [12][13][14][15][16][17], Saccharomyces cerevisiae [5,[18][19][20], Yarrowia lipolytic [21], and Corynebacterium glutamicum [22] by introducing particular biosynthesis pathways. However, the astaxanthin yields in these engineered microbes were still not high enough for cost-worthy commercialization.…”

In vitro and In vivo recombination of heterologous modules for improving biosynthesis of astaxanthin in yeast

“…According to the previous studies in our lab, combination of crtZ from Agrobacterium aurantiacum (Aa crtZ) and crtW from Brevundimonas vesicularis DC263(B. DC263 crtW) has a positive impact on the astaxanthin pathway in yeast [19,20]. Thus, AacrtZ and B. DC263crtW were chosen to construct the initial astaxanthin-producing strain.…”

“…Modifying microbial cells to improve the production of the desired endogenous or exogenous metabolites is a broad aim at many areas of academic, industrial biotechnology and biosciences [8][9][10][11]. In recent years, the heterologous biosynthesis of astaxanthin has been successfully achieved in Escherichia coli [12][13][14][15][16][17], Saccharomyces cerevisiae [5,[18][19][20],Yarrowia lipolytic [21], and…”