Ahmadi Hanie, Radford Devon, Kropinski Andrew M, Lim Loong-Tak, Balamurugan Sampathkumar
Department of Food Science, University of Guelph, Guelph, ON, Canada.
Guelph Research and Development Centre, Agriculture and Agri-Food Canada, Guelph, ON, Canada.
Front Microbiol. 2017 Dec 5;8:2375. doi: 10.3389/fmicb.2017.02375. eCollection 2017.
The study evaluated the thermal-stability of phages P100 and A511 at temperatures simulating the preparation of ready-to-eat meats. The phage infectivity after heating to 71°C and holding for a minimum of 30 s, before eventually cooling to 4°C were examined. Higher temperatures of 75, 80, and 85°C were also tested to evaluate their effect on phages thermal-stability. This study found that despite minor differences in the amino acid sequences of their structural proteins, the two phages responded differently to high temperatures. P100 activity declined at least 10 log (PFU mL) with exposure to 71°C (30 s) and falling below the limit of detection (1 log PFU mL) while, A511 dropped from 10 to 10 PFU mL. Cooling resulted in partial reconstitution of P100 phage particles to 10 PFU mL. Exposure to 75°C (30 s) abolished A511 activity (8 log PFU mL) and both phages showed reconstitution during cooling phase after exposure to 75°C. P100 exhibited reconstitution after treatment at 80°C (30 s), conversely A511 showed no reconstitution activity. Heating P100 to 85°C abolished the reconstitution potential. Substantial differences were found in thermal-stability and reconstitution of the examined phages showing A511 to be more thermo-stable than P100, while P100 exhibited reconstitution during cooling after treatment at 80°C which was absent in A511. The differences in predicted melting temperatures of structural proteins of P100 and A511 were consistent with the observed differences in thermal stability and morphological changes observed with transmission electron microscopy.
该研究评估了噬菌体P100和A511在模拟即食肉类制备温度下的热稳定性。检测了加热至71°C并保持至少30秒，最终冷却至4°C后的噬菌体感染性。还测试了75、80和85°C的更高温度，以评估它们对噬菌体热稳定性的影响。该研究发现，尽管它们结构蛋白的氨基酸序列存在微小差异，但这两种噬菌体对高温的反应不同。暴露于71°C（30秒）时，P100的活性至少下降10 log（PFU/mL），降至检测限以下（1 log PFU/mL），而A511从10⁸降至10⁵ PFU/mL。冷却导致P100噬菌体颗粒部分重构至10⁷ PFU/mL。暴露于75°C（30秒）使A511活性丧失（8 log PFU/mL），两种噬菌体在暴露于75°C后的冷却阶段均显示重构。P100在80°C（30秒）处理后表现出重构，相反，A511没有重构活性。将P100加热至85°C消除了其重构潜力。在所检测的噬菌体的热稳定性和重构方面发现了显著差异，表明A511比P100更耐热，而P100在80°C处理后的冷却过程中表现出重构，A511则没有。P100和A511结构蛋白预测解链温度的差异与通过透射电子显微镜观察到的热稳定性和形态变化差异一致。
