Thermal and chemical resistance of Lactobacillus casei and Lactobacillus paracasei bacteriophages.
OBJECTIVE
The survival of two collection Lactobacillus casei and L. paracasei bacteriophages when subjected to thermal and chemical treatments was investigated.


RESULTS
Thermal resistance was evaluated by heating phage suspensions at 63, 72 and 90 degrees C in three different media [Tris-magnesium gelatin (TMG) buffer: 10 mmol l(-1) Tris-Cl, 10 mmol l(-1) MgSO(4) and 0.1% w/v gelatin; Man Rogosa Sharpe (MRS) broth and reconstituted nonfat dry skim milk (RSM)]. A marked heat sensitivity was evident in both phages, as 15 min at 72 degrees C was enough to completely inactivate (6 log(10) reduction) them. No clear influence was demonstrated by the suspension media. The phages also showed similar resistance to biocides. Peracetic acid and sodium hypochlorite (800 ppm) were the most effective ones, destroying the phages within 5 min. Concentrations of 75 and 100% ethanol were not suitable to inactivate phage particles even after 45 min. Isopropanol did not show an effect on phage viability.


CONCLUSIONS
The data obtained in this work are important to design more effective control procedures in order to inactivate phages in dairy plants and laboratories.


CONCLUSIONS
This work will contribute to enhance the background knowledge about phages of probiotic bacteria.
Capra
M L
ML
Programa de Lactología Industrial, Facultad de Ingeniería Química, (Universidad Nacional del Litoral), Santiago del Estero, Santa Fe, Argentina.
Quiberoni
A
A
Reinheimer
J A
JA
D019840:2-Propanol / Q000494:pharmacology; D001435:Bacteriophages / Q000187:drug effects*; D003470:Culture Media / Q000737:chemistry; D003611:Dairy Products / Q000382:microbiology / Q000821:virology; D004202:Disinfectants / Q000494:pharmacology*; D000431:Ethanol / Q000494:pharmacology; D019649:Food Industry / Q000379:methods; D005516:Food Microbiology; D007778:Lactobacillus / Q000821:virology*; D010463:Peracetic Acid / Q000494:pharmacology; D012973:Sodium Hypochlorite / Q000494:pharmacology; D013696:Temperature; D010948:Viral Plaque Assay; D038301:Virus Inactivation
D003470:Culture Media; D004202:Disinfectants; D000431:Ethanol; D012973:Sodium Hypochlorite; D010463:Peracetic Acid; D019840:2-Propanol