The use of organic peroxyacids for the inactivation of calcium-mediated biofilm formation by Bacillus licheniformis

Biofilms formed by Bacillus licheniformis usually serve as a continuous bacterial contamination in the dairy industry. The purpose of this study was to explore how 1% organic acids (citric acid, phenyllactic acid, malic acid , and butyric acid) and their 1% organic peroxyacids (peroxycitric acid, peroxyphenyllactic acid, peroxymalic acid, and peroxybutyric acid) can inactive the planktonic and biofilm cells of B. licheniformis . Results demonstrated that the number of B. licheniformis planktonic cells was increased from 4 to 6.46 Log CFU mL −1 when treated with water. Organic peroxyacids, especially peroxyphenyllactic acid (PPA), obviously inactivated planktonic cells of B. licheniformis by a range of 3.32–4.14 Log CFU mL −1 . Moreover, organic peroxyacids could also decrease the cell surface hydrophobicity of bacteria, and effectively control the Ca 2+ -mediated biofilm formation by B. licheniformis in 96-well plates (reduction of OD values by 0.14–0.33) and on stainless steel (reduction of cell counts by 1.20–2.49 Log CFU cm −2 ). The low minimum biofilm eradication concentration of PPA (0.125%) also suggests its strong biofilm inactivation activity, which could serve as a novel and environmentally friendly biofilm control agent in the dairy industry.