Characterization of broad-host lytic Salmonella phages isolated from livestock farms and application against Salmonella Enteritidis in liquid whole egg

LWT ◽  
2021 ◽  
Vol 144 ◽  
pp. 111269
Author(s):  
Yue Yi ◽  
Ahmed G. Abdelhamid ◽  
Yumin Xu ◽  
Ahmed E. Yousef
Author(s):  
Malek Amiali ◽  
Michael Ngadi ◽  
James P. Smith ◽  
Vijaya Raghavan

This study sought to evaluate the effect of PEF parameters such as electric field intensity and number of pulses on the inactivation of Escherichia coli O157:H7 and Salmonella Enteritidis suspended in liquid whole egg. The medium was inoculated with 108 CFU ml-1 of E. coli O157:H7 or S. Enteritidis and was treated continuously at 10, 20 or 30°C using electric field intensity of either 20 or 30 kV cm-1. A biphasic instant reversal PEF waveform with up to 105 pulses of 2 µs in width was applied. Bacterial inactivation increased with increasing applied electric field intensity, number of pulses and processing temperature. Maximum reductions of 3.9 and 3.6 log cycles were obtained for E. coli O157:H7 and S. Enteritidis, respectively. The maximum input energies required to inactivate E. coli O157:H7 and S. Enteritidis were 538 and 914 J, respectively. The higher kinetic value was obtained for S. Enteritidis (0.043 µs-1) representing the more heat–PEF sensitive bacteria compared to E. coli O157:H7.


2006 ◽  
Vol 69 (9) ◽  
pp. 2066-2074 ◽  
Author(s):  
IGNACIO ALVAREZ ◽  
BRENDAN A. NIEMIRA ◽  
XUETONG FAN ◽  
CHRISTOPHER H. SOMMERS

Salmonella is a frequent contaminant on eggs and is responsible for foodborne illnesses in humans. Ionizing radiation and thermal processing can be used to inactivate Salmonella in liquid whole egg, but when restricted to doses that do not affect egg quality, these technologies are only partially effective in reducing Salmonella populations. In this study, the effect of ionizing radiation in combination with thermal treatment on the survival of Salmonella serovars was investigated. Of the six Salmonella serovars tested, Salmonella Senftenberg was the most resistant to radiation (Dγ = 0.65 kGy) and heat (D55°C = 11.31 min, z = 4.9°C). Irradiation followed by thermal treatment at 55 or 57°C improved the pasteurization process. Radiation doses as low as 0.1 kGy prior to thermal treatments synergistically reduced the D55°C and D57°C of Salmonella Senftenberg 3.6- and 2.5-fold, respectively. The D55°C and D57°C of Salmonella Typhimurium were reduced 2- and 1.4-fold and those of Salmonella Enteritidis were reduced 2- and 1.6-fold, respectively. Irradiation prior to thermal treatment would enable the reduction of heat treatment times by 86 and 30% at 55 and 57°C, respectively, and would inactivate 9 log units of Salmonella serovars.


1998 ◽  
Vol 61 (1) ◽  
pp. 107-109 ◽  
Author(s):  
RICHARD K. GAST ◽  
PETER S. HOLT

Culturing egg contents to detect Salmonella enteritidis (SE) has become an important tool for identifying infected laying flocks and thereby reducing the transmission of SE to humans by contaminated eggs. The present study evaluated the efficacy of supplementing incubating egg pools with selective and nonselective enrichment broth media (prepared at higher than usual concentrations) for rapidly isolating SE by a direct plating culture method. When 100-ml pools of liquid whole egg from a mixture of 60 egg contents were contaminated with approximately 10 SE cells each, supplementation with ferrous sulfate or with concentrates of either tryptone soya broth or Rappaport-Vassiliadis broth significantly improved SE recovery. When 100-ml egg-contents pools were contaminated with approximately 2 SE cells each, the addition of concentrated tryptone soya broth to incubating egg pools resulted in significantly better SE recovery than did iron supplementation. Efficient presumptive detection of very low incidences and levels of SE contamination by direct plating was thus accomplished in a total of 48 h by adding concentrated tryptone soya broth to incubating egg pools.


1995 ◽  
Vol 58 (3) ◽  
pp. 273-279 ◽  
Author(s):  
D. DOBBENIE ◽  
M. UYTTENDAELE ◽  
J. DEBEVERE

The effect of glucose oxidase (GOX) in different GOX/glucose combinations on four commonly occurring microorganisms in liquid whole egg was evaluated. The addition of a combination of 500 U GOX and 0.5 g glucose in 100 ml liquid whole egg killed Salmonella enteritidis, Micrococcus luteus and Bacillus cereus inoculated at 103cells/ml after 5 days of storage at 7°C, and showed a bacteriostatic activity on Pseudomonas fluorescens. The latter possesses the strongest catalase activity of the four bacteria tested, enabling it to more rapidly break down the hydrogen peroxide produced enzymatically by the GOX/glucose system. The efficacy of the above-mentioned combination was tested on the natural contamination flora of liquid egg and compared to the effect of a simple β-d-glucono-δ-lactone (GDL) treatment (0.7 g/100 ml). The GOX/glucose combination prolonged the lag phase by 6 days. Subsequently, the bacterial flora started to develop, but growth remained retarded by 2 log units. Since GDL did not exert antibacterial activity, growth inhibition by the GOX/glucose system cannot be ascribed to a pH decrease as a result of the production of gluconic acid in the system.


2000 ◽  
Vol 63 (4) ◽  
pp. 451-456 ◽  
Author(s):  
PILAR MAÑAS ◽  
RAFAEL PAGÁN ◽  
JAVIER RASO ◽  
FRANCISCO J. SALA ◽  
SANTIAGO CONDÓN

The resistance of Salmonella Enteritidis (ATCC 13076), Salmonella Typhimurium (ATCC 13311), and Salmonella Senftenberg 775W (ATCC 43845) to ultrasonic waves under pressure treatments, at sublethal (manosonication) and lethal temperatures (manothermosonication) in citrate–phosphate buffer and in liquid whole egg was investigated. The influence of treatment parameters on the inactivation rate of manosonication was also studied. Decimal reduction times (Dt) of Salmonella Enteritidis, Salmonella Typhimurium, and Salmonella Senftenberg 775W corresponding to a heat treatment at 60°C in pH 7 buffer and in liquid whole egg were 0.068, 0.12, and 1.0 min for buffer, and 0.12, 0.20, and 5.5 min for liquid whole egg. Those corresponding to a manosonication treatment (117 microns, 200 kPa, 40°C) in both media were 0.73, 0.78, and 0.84 min, and 0.76, 0.84, and 1.4 min, respectively. When the amplitude of ultrasonic waves was increased linearly, the inactivation rate of manosonication increased exponentially. The inactivation rate also increased when pressure was raised. However, the magnitude of this increase was progressively smaller at higher pressures. The magnitude of the influence of the amplitude of ultrasonic waves and static pressure on the inactivation rate of manosonication was the same in the three serotypes investigated. Whereas a heat treatment at 60°C only attained a ½-log cycle reduction in the number of Salmonella Senftenberg 775W survivors, a manothermosonication treatment (117 microns and 200 kPa) at this temperature attained a 3-log cycle reduction.


1971 ◽  
Vol 50 (6) ◽  
pp. 1772-1776 ◽  
Author(s):  
Roger Dabbah ◽  
W.A. Moats ◽  
V.M. Edwards

2006 ◽  
Vol 12 (5) ◽  
pp. 397-405 ◽  
Author(s):  
F. Sampedro ◽  
D. Rodrigo ◽  
A. Martínez ◽  
G. V. Barbosa-Cánovas ◽  
M. Rodrigo

This work overviews works published on the application of pulsed electric fields (PEF) in egg and egg derivatives, grouped by subject, and arranged chronologically in terms of the factor studied (microorganisms, quality aspects, shelf life and structural changes in gel formation properties). The inactivation of microorganisms by PEF in egg is very considerable, 3.5 decimal reductions in egg white were achieved by PEF in Salmonella enteritidis, 5.5 log reductions of Listeria innocua by means of a synergistic effect of PEF and nisin in liquid whole egg, and 5.6 log reductions of Escherichia coli in beaten fresh liquid egg by PEF treatment applied continuously or discontinuously in five steps. The shelf life of PEF-treated fresh liquid egg was extended to 4 weeks in refrigeration, and quality (colour, viscosity and sensory attributes) was not affected by PEF treatment. PEF treatment did not cause notable changes in proteins in a solution of ovalbumin and dialysed fresh egg white. However, some structural changes and functional modifications were observed in fresh egg white as a result of PEF treatment. The texture and microstructure of gels were affected by the application of PEF, and therefore PEF treatment conditions in egg white must be optimised to minimise possible modifications.


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