Fig. 4

Test of dCas12a-mediated CRISPRi system in isobutanol (IB)/3-methyl-1-butanol (3M1B)-producing Synechocystis strain with three different conditions: rhamnose induction timepoints, rhamnose concentrations for induction, and HCl titration. A Relative IB production per cell of strain HX11-ppc with varied rhamnose induction timepoints on days 2, 3, 4, and 5, compared to the levels of strain HX11-EVC. Three millimolar rhamnose were added for induction in strains HX11-EVC and HX11-ppc before inoculation, on days 0, 1, 2, 3, or no induction. B Relative 3M1B production per cell of strain HX11-ppc with varied rhamnose induction timepoints on days 2, 3, 4, and 5, compared to the levels of strain HX11-EVC. C Relative IB production per cell of strain HX11-ppc with varied rhamnose concentrations for induction on days 2, 3, 4, and 5, compared to the levels of strain HX11-EVC. Rhamnose (0 mM, 1 mM, 3 mM, 5 mM, or 10 mM) was added for induction in strains HX11-EVC and HX11-ppc on day 1. D Relative 3M1B production per cell of strain HX11-ppc with varied rhamnose concentrations for induction on days 2, 3, 4, and 5, compared to the levels of strain HX11-EVC. E Relative IB production per cell of strain HX11-ppc cultivated with or without HCl titration on days 2, 3, 4, and 5, compared to the levels of strain HX11-EVC. Three millimolar rhamnose were added for induction in strains HX11-EVC and HX11-ppc on day 1. The target pH range of the cultures with HCl titration was between 7 and 8. F Relative 3M1B production per cell of strain HX11-ppc cultivated with or without HCl titration on days 2, 3, 4, and 5, compared to the levels of strain HX11-EVC. Results are the mean of three biological replicates. Error bars represent standard deviation