Figure 4. Phenotype visualisation of L. lactis cells using the NZ9000Erm, NZ9000NisI and NZ9000NisIΔ22 strain.

The different strains were grown until exponential phase (OD₆₀₀ = 0.5). During growth, different concentrations of nisin were added (0, 1, 10 and 30 nM). The cells were transferred and fixed onto a coverslide and the cells were visualised using a Nikon eclipse Ti microscope. The chains were counted and categorized in different classes. Class 1 consisted of 1–2 cocci (black bar), class 2 consisted of 3–5 cells (grey bar), class 3 consisted of 6–10 cells (dark grey bar), class 4 comprised of 11–20 cells (light grey) and class 5 comprised of >20 cells. For each sample the number of counted cells per area was >50. In total, after scanning five different areas at least >500 cell chains were observed.