Fig. 3. BTI reduces biofilm-related phenotypes of V. vulnificus.

(A) Relative mRNA expression levels of brpA, brpN, cabA, cabH, and brpT relative to those in the parental wild-type (set as 1). (B) Quantification of biofilm formation in V. vulnificus strains grown with varying BTI concentrations. Biofilms were stained with crystal violet and measured at A₅₇₀ after elution. (C) Representative image of colony rugosity of V. vulnificus strains in the presence or absence of 100 μM BTI after 24 h incubation. Scale bar represents 1 mm. (D) Survival of V. vulnificus against antibiotics. Biofilms were grown with 100 μM BTI (or 1% DMSO for control) for 24 h and then treated with various concentrations of ampicillin for 8 h. Viable cells after ampicillin treatment were counted. JN111, a parental wild-type strain, and ΔbrpT, a brpT deletion mutant, were used. Data represent means ± SEMs from three independent experiments. Statistical significance was determined by Student’s t-test (****, p < 0.0001; ***, p < 0.0005; **, p < 0.005; *, p < 0.05; ns, not significant). wt, wild-type; Vv, V. vulnificus.