Figure 4.

Effect of lysozyme on Synechococcus cell disintegration. Cells were cultivated for 48 hours with either low (0.24 g NaNO₃ L^-1) or high (1.0 g NaNO₃ L^-1) initial nitrate concentrations to generate ‘carbohydrate-loaded biomass’ or ‘reference biomass’, respectively. Cell suspensions were concentrated five times (by centrifugation and re-suspension in a smaller volume of the supernatant) and stored at either at 4°C (open circles) or at -20°C (solid circles) for 1 hour prior to incubation with lysozyme (100 mg L^-1) at 37°C. Cell disintegration was followed over time by measuring the OD₇₃₀ after appropriate dilution of small aliquots of the reaction mixture into water. The OD₇₃₀ is depicted as percentage of the OD₇₃₀ at the start of the lysozyme treatment. (A) Reference Synechococcus cells. (B) Carbohydrate-loaded Synechococcus cells. h, hours; OD₇₃₀, optical density at 730 nm.