Thermal Destruction Kinetics of a Lactic Streptococcal Bacteriophage

Abstract

The aim of the study was to elucidate the kinetics of thermal destruction of a lactic streptococcal bacteriophage, and to determine the effect of varied propagation and heating conditions on its thermoresistance. The propagation medium and temperature affect the degree of thermostability of the phage produced; higher incubation temperature enhances thermostability. The composition and reaction of the heating menstruum are also of significance. Phage thermoresistance increased significantly with the phosphate and whey levels. The effect of various minerals was difficult to resolve, mainly because of the bimodal nature of the survival curve. Thermoresistance was highest at p H 6, intermediate at p H 7, and lowest at p H 8. The kinetics of inactivation of this phage deviated from those of a first-order reaction. Consequently, a special treatment of the data was required in order to compute the various thermodynamic parameters that define the reaction. The high positive values of Q 10 , energy of inactivation, and entropy appear to indict protein denaturation as the cause of phage destruction.

Thermal, Chemical, and Photocatalytic Inactivation of Lactobacillus plantarum Bacteriophages

“…Consequently, the suspension media used in the industry could have a protective effect on L. plantarum phages. The same result for phage suspensions in milk was reported for streptococcal (11) and Lactococcus lactis (15,47) phages. Fabrizio et al (15) reported a moderate increase in the heat resistance of Lactococcus lactis phages when whole milk was used instead of skim milk.…”

“…These phages have been characterized mainly by their genomes (8,10,14,26,27,39,49,52) and by their interactions with sensitive bacterial strains (8,27,39,49); however, data on their chemical and thermal resistance are scarce. In contrast, data have been reported on thermal and chemical resistance of phages infecting Lactococcus (2,5,11,15,20,43,47,51,53), Streptococcus thermophilus (3), Lactobacillus casei and Lactobacillus paracasei (7), Lactobacillus delbrueckii (44), and Lactobacillus helveticus (45).…”

Bacteriophages Isolated From Turkeys Infecting Diverse Salmonella Serovars

“…Several other studies also noted that the medium components of phage solution could affect the thermal stability of phages ( Fabrizio et al, 1999 ; Sua’/rez and Reinheimer, 2002 ; Quiberoni et al, 2003 ; Briggiler Marco et al, 2009 ). It was reported that reconstituted non-fat dry skim milk is more protective than De Man, Rogosa and Sharpe (MRS) broth against thermal inactivation of some dairy phages ( Daoust et al, 1965 ; Quiberoni et al, 2003 ). Whole milk provides better thermal protection than skim milk for Lactococcus lactis phages ( Fabrizio et al, 1999 ).…”