FIG 5 .
The FUN-LOV switch allows precise control of flocculation by light conditions. (A) FUN-LOV-dependent expression of FLO1 or TUP1 genes allows flocculation to occur in light (FIL) or in darkness (FID). (B) FIL and FID phenotypes observed as macroscopic cell aggregation in culture flasks (bottom view) and fluorescence microscopy of cells expressing mCherry under the PTDH3 constitutive promoter. Experiments were performed under constant white-light (LL) or constant darkness (DD) conditions. The BY4741 wild-type (wt) and BY4741 tup1Δ strains were utilized as negative and positive controls of flocculation, respectively. Cell aggregates are indicated by arrows; bar, 100 µm. (C) Quantification of the FIL and FID phenotypes observed in panel B by calculating the flocculation index. Statistically significant differences between LL and DD conditions are indicated as ** (t test, P < 0.01).