Fig 4. Treatment of biofilms with nisin A and nisin I4V peptides.

(A) S. pseudintermedius DK729 and (B) S. pseudintermedius DSM 21284 with 1, 2, 4, 8 and 16X MIC of nisin A and nisin I4V peptides for 24 hrs as evaluated by crystal violet (CV) staining. The amount of biofilm was quantified by measuring the OD₅₉₅ of CV dissolved in acetic acid. The means and standard deviations of triplicate determinations are presented. Asterisks indicate statistically significant differences (Student’s t-test) between peptides used at similar concentration (* = p < 0.05, ** = p < 0.01, *** = p < 0.001).