Degradation of biofilm by phages belonging to the genus .

Unlabelled: is a pathogenic foodborne bacterium that is a significant cause of mortality associated with foodborne illness and causes many food recalls attributed to a bacteriological cause. Their ability to form biofilms contributes to the persistence of spp. in food processing environments. When growing as biofilms, are more resistant to sanitizers used in the food industry, such as benzalkonium chloride (BAC), as well as to physical stresses like desiccation and starvation. Lytic phages of are antagonistic to a broad range of spp. and may, therefore, have utility in reducing the occurrence of -associated food recalls by preventing food contamination. We screened nine closely related phages, including the commercially available Listex P100, for host range and ability to degrade microtiter plate biofilms of ATCC 19111 (serovar 1/2a). One phage, CKA15, was selected and shown to rapidly adsorb to its host under conditions relevant to applying the phage in dairy processing environments. Under simulated dairy processing conditions (SDPC), CKA15 caused a 2-log reduction in 19111 biofilm bacteria. This work supports the biosanitation potential of phage CKA15 and provides a basis for further investigation of phage-bacteria interactions in biofilms grown under SDPC.

Importance: is a pathogenic bacterium that is especially dangerous for children, the elderly, pregnant women, and immune-compromised people. Because of this, the food industry takes its presence in their plants seriously. Food recalls due to are common with a high associated economic cost. In food-processing plants, spp. typically reside in biofilms, which are structures produced by bacteria that shield them from environmental stressors and are often attached to surfaces. The significance of our work is that we show a bacteriophage-a virus-infecting bacteria-can reduce counts by two orders of magnitude when the bacterial biofilms were grown under simulated dairy processing conditions. This work provides insights into how phages may be tested and used to develop biosanitizers that are effective but are not harmful to the environment or human health.