Nine Leuconostoc mesenteroides phages were isolated during blue cheese manufacture yielding faulty products with reduced eye formation. Their morphologies, restriction profiles, host ranges and long-term survival rates (25 °C, 8 °C, −20 °C and −80 °C) were analysed. Based on restriction analysis, six of them were further examined regarding resistance to physical (heat and high pressure homogenization, HPH) and chemical treatments (ethanol, sodium hypochlorite, peracetic acid, biocides A, C, E and F). According to their morphology, L. mesenteroides phages studied in the present work belonged to the Caudovirales order and Siphoviridae family. Six distinct restriction patterns were obtained with EcoRV, HindIII, ClaI and XhoI enzymes, revealing interesting phage diversity in the dairy environment. No significant reductions in phage counts were observed after ten months of storage at –20 °C and −80 °C, while slightly and moderate decrease in phage numbers were noticed at 8 °C and 25 °C, respectively. The phages subjected to heat treatments generally showed high resistance at 63 °C andmoderate resistance at 72 °C. However, 80 °C for 30min and 90 °C for 2min led to complete inactivation of viral particles. In general, the best ethanol concentration testedwas 75%, as complete inactivation for most Leuconostoc phages within 30 min of incubation was achieved. Peracetic acid, and biocides A, C, E and F were highly effectivewhen used at the sameor at amoderately lower concentration as recommended by the producer. Usually,moderate or high concentrations (600–1600 ppm) of sodiumhypochlorite were necessary to completely inactivate phage particles. Leuconostoc phages were partially inactivated by HPH treatments as remaining viral particles were found even after 8 passes at 100 MPa. This is the first report of L. mesenteroides phages isolated from an Argentinean dairy cheese plant. The results of this work could be useful for establishing the most effective physical and chemical treatments for inactivating phages in industrial plants and laboratory environments.
Silvina A. Pujato, Daniela M. Guglielmotti, Hans-W. Ackermann, Francesca Patrignani, Rosalba Lanciotti, Jorge A. Reinheimer, et al. (2014). Leuconostoc bacteriophages from blue cheese manufacture: long-term survival, resistance to thermal treatments, high pressure homogenization and chemical biocides of industrial application. INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY, 177, 81-88 [10.1016/j.ijfoodmicro.2014.02.012].
Leuconostoc bacteriophages from blue cheese manufacture: long-term survival, resistance to thermal treatments, high pressure homogenization and chemical biocides of industrial application
PATRIGNANI, FRANCESCA;LANCIOTTI, ROSALBA;
2014
Abstract
Nine Leuconostoc mesenteroides phages were isolated during blue cheese manufacture yielding faulty products with reduced eye formation. Their morphologies, restriction profiles, host ranges and long-term survival rates (25 °C, 8 °C, −20 °C and −80 °C) were analysed. Based on restriction analysis, six of them were further examined regarding resistance to physical (heat and high pressure homogenization, HPH) and chemical treatments (ethanol, sodium hypochlorite, peracetic acid, biocides A, C, E and F). According to their morphology, L. mesenteroides phages studied in the present work belonged to the Caudovirales order and Siphoviridae family. Six distinct restriction patterns were obtained with EcoRV, HindIII, ClaI and XhoI enzymes, revealing interesting phage diversity in the dairy environment. No significant reductions in phage counts were observed after ten months of storage at –20 °C and −80 °C, while slightly and moderate decrease in phage numbers were noticed at 8 °C and 25 °C, respectively. The phages subjected to heat treatments generally showed high resistance at 63 °C andmoderate resistance at 72 °C. However, 80 °C for 30min and 90 °C for 2min led to complete inactivation of viral particles. In general, the best ethanol concentration testedwas 75%, as complete inactivation for most Leuconostoc phages within 30 min of incubation was achieved. Peracetic acid, and biocides A, C, E and F were highly effectivewhen used at the sameor at amoderately lower concentration as recommended by the producer. Usually,moderate or high concentrations (600–1600 ppm) of sodiumhypochlorite were necessary to completely inactivate phage particles. Leuconostoc phages were partially inactivated by HPH treatments as remaining viral particles were found even after 8 passes at 100 MPa. This is the first report of L. mesenteroides phages isolated from an Argentinean dairy cheese plant. The results of this work could be useful for establishing the most effective physical and chemical treatments for inactivating phages in industrial plants and laboratory environments.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
