Table 2.

Engineering microorganisms for astaxanthin production

Strain	Strategy	Cultivation mode	Astaxanthin yield	Refs.
E. coli	Gene screening (four CrtZ and twelve CrtW genes) and gene combination	Shake flask	1.99 mg/g DCW	Scaife et al. (2012)
E. coli	Genomic integration (crtE, crtB, crtI, crtY and crtZ genes from P. ananatis as well as crtW148 gene from N. punctiforme PCC 73102) and promoter engineering	Shake flask	1.4 mg/g DCW	Lemuth et al. (2011)
E. coli	Optimization of gene expression via ribosome-binding site combinatorics	Shake flask	5.8 mg/g DCW	Zelcbuch et al. (2013)
E. coli	Gene mining of CrtE and CrtZ genes from Sphingomonas sp. ATCC 55669	Shake flask	6.6 mg/g DCW	Ma et al. (2016)
E. coli	Combinatorial expression of different β-carotene ketolase and ketolases	Shake flask	7.4 ± 0.3 mg/g DCW	Lu et al. (2017)
E. coli	Pathway engineering- metabolic engineering of DXP pathway by introduction of genes from Kocuria gwangalliensis, as well as introduction of astaxanthin downstream biosynthetic pathway from Paracoccus haeundaensis	Shake flask	1100 μg/g DCW	Jeong et al. (2018)
E. coli	Optimization of gene codon, promoters, strain species and culture media	Shake flask	4.30 ± 0.23 mg/g DCW 24.16 ± 2.03 mg/L	Li and Huang (2018)
E. coli	Comprehensive metabolic engineering, consisting of optimization of β-carotene biosynthetic pathway, introduction of CrtZ from Pantoea ananatis and CrBKT from Chlamydomonas reinhardtii, truncation of CrBKT, culture condition optimization, strengthening of DXP pathway and uptake of glycerol, introduction of hok/sok system for improving the stability of hereditary stability	Fed-batch fermentation	432.82 mg/L	Park et al. (2018)
E. coli	Optimization of the localization of CrtZ and CrtW enzymes; a total of 215.4% improved production of astaxanthin was achieved by combining CrtZ and CrtW together with a linker and locating them on the cell membrane	Shake flask	No clear data	Ye et al. (2018)
E. coli	Multidimensional heuristic process was proposed to optimization of the long astaxanthin biosynthetic pathway, via inter-module balance by varying promoter strength and intra-module balance by using different RBSs	Shake flask	15.1 mg/g DCW 320 mg/L	Zhang et al. (2018b)
E. coli	Optimization of gene expression by using different inducible and constitutive promoters	Shake flask	8.3 mg/g DCW	Chou et al. (2019)
E. coli	Optimization of cell morphology and oxidative stress for increasing astaxanthin yield, via gene mining and gene deletion. A complementary temperature-sensitive plasmid was introduced to further balance cell growth and production accumulation	Fed-batch fermentation	432.82 mg/L	Lu and Liu (2019)
E. coli	Gene fusion of CrtW and CrtZ	Shake flask	576.4 μg/g DCW	Nogueira et al. (2019)
E. coli	Assembly of the key enzymes in the MVA pathway (ACAT, HMGS, HMGR) into multi-enzyme complexes via orthogonal protein reactions (SpyCatcher/SpyTag and SnoopCatcher/SnoopTag pairs)	Shake flask	1 mg/g DCW	Qu et al. (2019)
E. coli	Gene screening and enzyme fusion of CrtZ and CrtW, replacement of different linkers, carbon source optimization	Shake flask	26.16 mg/L (5.18 mg/g DCW)	Wu et al. (2019b)
E. coli	Coordinated expression of astaxanthin biosynthesis genes – CrtW, CrtZ, CrtY, and regulation of molecular chaperone genes groES-groEL in the beta-carotene producing strain CAR026 (3.6 g/L)	Fed-batch fermentation	1.18 g/L	Gong et al. (2020)
C. glutamicum	Balancing the metabolic flux of CrtZ and CrtW via selection and combination of different enzymes, optimization of RBS, and initiation codon	Shake flask	0.4 mg·L−1·h−1	Henke et al. (2016)
C. glutamicum	Gene fusion of CrtZ and CrtW (CrtZ-CrtW help to accumulation astaxanthin while CrtZ-CrtW cannot produce astaxanthin); usage of combined carbon sources—glucose and acetic acid	Shake flask	3.1 mg/g DCW	Henke and Wendisch (2019)
C. utilis	Expression of CrtE, CrtB, CrtI, CrtY, CrtZ and CrtW genes with constitutive promoters	Shake flask	0.4 mg/g DCW	Miura et al. (1998)
Y. lipolytica	Introduction of CrtYB, CrtI, and CrtE gene from Phaffia rhodozyma, overexpression of endogenous tHMG1, multi-copy integration of CrtZ and CrtW gene into the genome, deregulation of ERG9	96-well plates	3.5 mg/g DCW 54.6 mg/L	Kildegaard et al. (2017)
Y. lipolytica	Optimization of the synthetic pathway of β-carotene precursor; optimization of the copy number as well as gene origins of β-ketolase and β-hydroxylase	Fed-batch fermentation	285 ± 19 mg/L	Tramontin et al. (2019)
K. marxianus	Gene screening of CrtZ and integration of astaxanthin biosynthetic pathway	Shake flask	No clear information	Chang et al. (2015)
K. marxianus	Site mutation of CrtZ and overexpression of the key enzymes in the limiting steps	Batch fermentation	9.972 mg/g DCW	Lin et al. (2017)
S. cerevisiae	Overexpression of Crt genes from Phaffia rhodozyma or bacteria	Shake flask	29 μg/g DCW	Ukibe et al. (2009)
S. cerevisiae	Gene cloning, codon optimization and copy number optimization of CrtZ and BKT from H. pluvialis	Shake flask	4.7 mg/g DCW	Zhou et al. (2015a)
S. cerevisiae	Strengthening MVA pathway and β-carotene biosynthetic pathway, site-directed evolution of BKT, optimization of gene copy number, strain hybridization	Shake flask	8.10 mg/g DCW 47.18 mg/L	Zhou et al. (2017a)
S. cerevisiae	Combination of different CrtZ and CrtW genes from diverse origins, improvement of CrtZ promoter strength	Shake flask Fed-batch fermentation	4.5 mg/g DCW 81.0 mg/L	Chen et al. (2017a)
S. cerevisiae	Directed coevolution of β-carotene ketolase and hydroxylase, dynamic control of gene expression using temperature signal	Fed-batch fermentation	235 mg/L	Zhou et al. (2019)
S. cerevisiae	Introduction of CrtZ from Agrobacterium aurantiacum, atmospheric and room temperature plasma mutagenesis (ARTP)	Fed-batch fermentation	217.9 mg/L	Jin et al. (2018)
S. cerevisiae	Physical mutagenesis by ARTP and adaptive evolution driven by H2O2	Fed-batch fermentation	404.78 mg/L	Jiang et al. (2020)
S. cerevisiae	In vitro and in vivo recombination of diverse heterologous CrtZ and CrtW genes	Shake flask	6.05 mg/g DCW	Qi et al. (2020)