Figure 2.

Growth, extracellular proteolytic activity and colony spreading of F. psychrophilum wild-type and fpgA ⁻ strains. (A) Growth curve at 12 °C in NBF medium, monitored by determining OD₅₂₅. (■) wild-type and (●) fpgA⁻ strains. Extracellular caseinolytic activity in cell-free supernatants was determined with azocasein as described by Secades et al. [38]. (□) wild-type and (○) fpgA⁻ strains. EU, enzyme units. (B) Colony spreading of F. psychrophilum strains grown on 1/6NA for 96 h at 20 °C according to Pérez-Pascual et al. [37]. (a) wild-type; (b) fpgA⁻; and (c) fpgA⁺ (complemented strain).