Table 2.

Examples of genetic engineering of microalgae for lipid synthesis.

Microalgae Strain	Gene/Target Site	Approach	Results	References
Synechocystis sp. PCC 6803	Acyl-ACP synthetase (aas)	Overexpression of aas	Increased lipid production by 5.4%	Eungrasamee et al. [60]
Chlamydomonas reinhartdii	Phospholipase A2 (PLA2)	Knock-out/CRISPR/Cas9	Improves the lipids’ production up to 64.25%	Shin et al. [62]
Chlamydomonas reinhardtii PTS42	Malic enzyme isoform 2 (ME2)	Overexpression	Increasing lipid rate up to 23.4%	Kim et al. [46]
Chlamydomonas reinhardtii CC400	PEPC1	Down regulation by CRISPRi/Cas9	Lipid (content and productivity of 28.5% DCW and 34.9 mg/L/day)	Kao and Ng. [63]
Chlamydomonas reinhardtii	HpDGAT2D	Heterologous expression	Increasing TAG content by ~1.4-fold	Cui et al. [64]
Chlamydomonas reinhardtii CC-4349	ZEP and AGP genes	CRISPR-Cas9 RNP-mediated knock-out method	Increased oil productivity by 81%	Song et al. [65]
Nannochloropsis oceanica	AtDXS gene	Engineering a control-knob gene	Lipid production increased by ~68.6% in nitrogen depletion and ~110.6% in high light	Han et al. [66]
Phaeodactylum tricornutum.	GPAT and DGAT2 genes	Overexpression	Total lipid content increased by 2.6-fold and reached up to 57.5% DCW	Zou et al. [67]
Nannochloropsis salina	bZIP	Overexpressed a bZIP TF, NsbZIP1	Lipid production increased by 50%	Kwon et al. [68]
Scenedesmus obliqnus	Differential expression genes (DEGs)	up-regulated genes	Lipid yield increased by 2.4 fold	Xi et al. [69]
Phaeodactylum tricornutum	ptTES1	Transcription activator-like effector nucleases (TALENs)	1.7-fold increase in TAG content	Hao et al. [70]
Nannochloropsis oceanica	Transposome	Insertion of a Transposome complex (mutagenesis)	Increased PUFA by 180% and EPA by 40%	Osorio et al. [71]
Phaeodactylum tricornutum	PhyA	Overexpression	Increased DHA by 12% and EPA by 18%	Pudney et al. [72]
Synechocystis sp.	Acetyl-CoA carboxylase (ACC)	Overexpression	Increased its lipid content by 3.6-fold	Fathy et al. [73]
Chlamydomonas reinhardtii	Diacylglycerol acyltransferase 2 (DGAT)	Heterologous expression	α-linolenic acid, an important omega-3 fatty acid, was improved by more than 12%	Ahmad et al. [51]