Sustainable production of astaxanthin in microorganisms: the past, present, and future

Metabolic Engineering for Efficient Ketocarotenoid Accumulation in the Green Microalga Chlamydomonas reinhardtii

“…8,9 Heterologous astaxanthin biosynthesis has been established in several heterotrophic microbes including Escherichia coli, 10,11 Corynebacterium glutamicum, 12,13 and Saccharomyces cerevisiae. 14,15 Heterologous production in microbial hosts typically involves carotenoid pathway reconstitutions using both, pro-and eukaryotic pathway enzymes as well as enhancing flux toward isoprenoid biosynthesis by modification of MEP/mevalonate (MVA) pathways. Fermentative hosts can achieve relatively high volumetric production titers of heterologous astaxanthin.…”

“…The ß-carotene path enables the synthesis of the xanthophylls, zeaxanthin and violaxanthin, which are bound by antenna proteins of photosystems, increase light harvesting efficiency, serve as major energy quenching molecules, and play important roles in cellular protection against excessive light and reactive oxygen species (ROS) . The final synthesis of astaxanthin is achieved by oxidation of both zeaxanthin β-rings or alternatively of β-carotene into canthaxanthin, followed by hydroxylation. , Heterologous astaxanthin biosynthesis has been established in several heterotrophic microbes including Escherichia coli, , Corynebacterium glutamicum, , and Saccharomyces cerevisiae. , Heterologous production in microbial hosts typically involves carotenoid pathway reconstitutions using both, pro- and eukaryotic pathway enzymes as well as enhancing flux toward isoprenoid biosynthesis by modification of MEP/mevalonate (MVA) pathways. Fermentative hosts can achieve relatively high volumetric production titers of heterologous astaxanthin.…”

High astaxanthin production by Xanthophyllomyces dendrorhous strain DW6 from cane molasses using two-stage pH strategies

“…As mentioned, astaxanthin is a fat-soluble compound mainly stored in lipid droplets, cell membranes and organelle membranes of cells, which could affect the microbial metabolism and cause toxicity to the cells. 33 Based on the above results, it was found that pH values can significantly affect the microbial growth and astaxanthin synthesis of strain DW6. Accordingly, a two-stage pH fermentation strategy was developed to de-couple the microbial growth and astaxanthin synthesis, thus reducing the metabolic burden and improving the astaxanthin production efficiency of strain DW6.…”

“…32 One β-carotene hydroxylase (crtR) [EC:1.14.13.-] belonging to the cytochrome P450 protein family was identified in strain DW6, which can provide crtS with the necessary electrons for the substrate oxygenation. 33 Studies have shown that β-carotene cannot be converted to astaxanthin without the assistance of crtR, a crucial enzyme in astaxanthin synthesis. 32…”

Optimized Protocol for Microalgae DNA Staining with SYTO9/SYBR Green I, Based on Flow Cytometry and RSM Methodology: Experimental Design, Impacts and Validation

“…Microalgae are photosynthetic microorganisms that constitute the basis of life in a variety of marine and freshwater ecosystems [ 1 , 2 ]. They are becoming increasingly important in the bioeconomy and biotechnology sector as an attractive, sustainable source of value-added products [ 1 , 2 , 3 , 4 ], owing to their enormous potential for the production of industrially relevant, high-value products, e.g., pigments with antioxidant and antibacterial activity such as carotenoids (astaxanthin, canthaxanthin, β-carotene and lutein) [ 5 , 6 , 7 ], polysaccharides (hydro colloids, e.g., sulfated polysaccharides) [ 8 ] and polyunsaturated and omega-3 fatty acids (e.g., eicosapentaenoic acid or docosahexaenoic acid) [ 9 , 10 ]. Thus, to develop feasible algae-based bioprocesses, it is crucial to study their intrinsic characteristics, such as their physiology, metabolism and their response to factors influencing their growth [ 4 , 11 , 12 , 13 ].…”