Fig. 4

Hypothetical circuits proposed with the help of genetic modules (plasmids a, b, c) that can be applied to microalgae with light intensity stimulus. Case 1. Input (plasmid a + b) = light-inducible promoter::gRNA for transcription factor (PSR1/NRR1)^a + light-inducible promoter::dCas9/VP64(CRISPRa) = activation of lipid pathway (Output). Case 2. Input (plasmid a + c) = light-inducible promoter::gRNA for transcription factor (Zn(II)₂Cys₆)^b + light-inducible promoter::dCas9/SRDX(CRISPRi) = inactivation of lipid pathway suppressors (Output). ^aPSR1 and NRR1 are transcription factors that get induced during stress which leads to lipid accumulation [171, 172]. ^bZn(II)₂Cys₆ is a transcription factor that negatively regulates lipid accumulation under nitrogen stress [183]