Impact of thermal and biocidal treatments on lactococcal 936-type phages

Biocidal Inactivation of Lactococcus lactis Bacteriophages: Efficacy and Targets of Commonly Used Sanitizers

“…These were purchased either as pure powders/solutions or as mixtures of compounds in the case where purpose-made sanitizers designed for the dairy industry were employed. As sodium hypochlorite and peracetic acid have recently been examined using a number of the phages involved in this study (Murphy et al, 2014 ), these were omitted.…”

“…These include (i) heat treatment of milk via pasteurization; (ii) high pressure treatments; (iii) the use of strain rotations and so-called direct vat starters (DVS) to prevent the proliferation of phages, along with the concomitant development of phage-resistant strains for use in these rotations (Moineau, 1999 ); (iv) the improvement of dairy plant facilities, such as plant design optimization and the use of closed vats (Allison and Klaenhammer, 1998 ); and (v) the utilization of commercial chemicals for the sanitization and disinfection of plant equipment and facilities. While these strategies have been relatively effective, with complete product loss now very rare (Madera et al, 2004 ), phage-associated fermentation issues are still a very common occurrence in dairy plants, probably because phages have adapted to overcome one or more of the imposed hurdles (Atamer et al, 2011 ; Mercanti et al, 2012 ; Murphy et al, 2014 ).…”

“…The precise mode of action of many antimicrobial compounds on bacteria has been widely studied, with much now known about the specific targets and anti-bacterial mechanisms of many biocides (McDonnell and Russell, 1999 ; Maillard, 2002 ; Wessels and Ingmer, 2013 ). In contrast, relatively scarce data currently exists pertaining to the virucidal mode of action of biocides (Garneau and Moineau, 2011 ; Murphy et al, 2014 ). However, while precise structural targets in phages are, as yet, largely uncharacterised, numerous studies have been performed on the efficacy of phage inactivation by commercially employed biocides.…”

“…For example, a number of studies have been performed on the effectiveness of peracetic acid and sodium hypochlorite as virucidal agents (Binetti and Reinheimer, 2000 ; Capra et al, 2004 ; Avsaroglu et al, 2007 ). Quaternary ammonium compounds have also proved effective (Campagna et al, 2014 ), as has sodium hydroxide (Murphy et al, 2014 ). However, despite the proven effectiveness of these biocides, phages continue to persist in dairy facilities, and a possible contributing factor to this may be variations and/or increases in phage resistance to biocides.…”

Bacteriophages in the Dairy Environment: From Enemies to Allies

“…The majority of disinfectants consist of several biocides and they must ensure the lack of negative impact on the final product and be able to degrade into harmless final compounds. Combining biocides and heat or using them at extreme pH conditions have shown to give the best results [ 38 ]. Photocatalysis intended to destroy fungi, bacteria and spores in the air has been recently explored for inactivating viruses infecting Lactobacillus casei , Lb.…”