FIGURE 1.

(A) Dose dependent inhibition of Streptomyces sp. SBT343 extract on biofilm formation of S. epidermidis RP62A on polystyrene flat-bottom 96-well plates. S. epidermidis RP62A treated with the extract from modified ISP2 medium (250 μg/ml) served as the appropriate control in the experiment. (B) Growth curve of S. epidermidis RP62A in the presence of BIC₅₀ (62.5 μg/ml) and highest tested concentration (125 μg/ml) of the SBT343 extract. (C) Investigation of the Streptomyces sp. SBT343 for induction of PIA-independent biofilm formation in S. epidermidis RP62A. Control and the residual biofilms after the extract treatment (250 μg/ml) were subjected to two parallel treatments (i) with metaperiodate (NaIO_4-T), which is suitable to dissolve the PIA-matrix proportion of the biofilm, and (ii) with proteinase K (proteinase K_-T) which will reduce proteins engaged in the biofilm matrix. Biofilm measurements were done shortly after the respective treatments, and the total biofilm levels were compared with the untreated control and residual biofilm sets. The biofilm-negative S. epidermidis ATCC12228 served as the negative control. S. epidermidis RP62A treated with the extract from modified ISP2 medium (250 μg/ml) served as the appropriate control. Graphs represent mean values ± SEM from three independent repetitions of the experiment done in quadruplicate. ns, not significant, ^∗∗∗∗p < 0.0001.