Fig. 2.

Rifampicin resistance, proteolytic and haemolytic activity, production of antibiotics and biofilm formation of P. luminescens strains TT01 and DJC. a Growth and extracellular activities of P. luminescens strain TT01 (upper panel) and strain DJC (lower panel). (i) Resistance towards rifampicin (50 μg/ml) after 48 h of incubation at 30 °C. (ii) Proteolytic activity on Ca-caseinate plates after 48 h of incubation at 30 °C. (iii) Secreted haemolytic activity of P. luminescens TT01 and DJC on sheep red blood agar plates after 4 days of incubation at 30 °C. (iv) Antibiotic effect on B. subtilis agar plates after 48 h of incubation at 30 °C. b Biofilm formation. Crystal violet staining of P. luminescens strain TT01 and DJC grown in LB broth and cultivated for 72 h under gentle shaking (150 rpm) at 30 °C. The planktonic cells were removed and the sessile cells, i.e. biofilm, was stained violet. The stained plates are shown on the left panel (i), whereby the quantification of the staining is shown right (ii). The asterisks (**) indicate statistically significant differences with a p-value smaller than 0.001. Error bars and values represent standard error of three independently performed experiments