Pinturas fotocatalíticas para la inactivación de fagos de bacterias lácticas

Abstract

Phage infections can cause severe problems against fermentative processes in the dairy industry due to cell lysis of the starter cultures. The aim of this work was to investigate the inactivation of nine phages infective to lactic acid bacteria applying photocatalytic paints irradiated with visible light (λ 360-720 nm). To elaborate the paints, anatase form of titanium dioxide containing carbon as doping agent (18% w/w) was used in replacement of the normal paint pigments, then the paints showed photocatalytic activity in the UV-VIS spectrum. The assays were carried out in a laboratory reactor at constant humidity and temperature (80%, 30°C). Phages were placed on plates covered with the paint and subjected to visible radiation.Samples were taken at different times and phage enumerations (plaque-forming units per mL, PFU/mL) were determined by the double-layer plaque titration method. A total inactivation (< 50 PFU/mL) for five phages (within 2-5 h) were obtained. On the other hand, four phages partially reduced their infectivity between 2.9 and 5.9 orders log. The results obtained in this work showed the efficiency of the photocatalytic paints in the inactivation of dairy phage. These paints could be applied on interior walls and diverse industrial surfaces, as an alternative to decrease the risk of phage infections in the dairy industry. This will contribute to decrease the phage load of bioaerosols, which constitute the main dissemination via of phages in industrial environments.