Rodriguez Oscar, Castell-Perez M Elena, Ekpanyaskun Nont, Moreira Rosana G, Castillo Alejandro
Department of Biological and Agricultural Engineering, Texas A and M University, College Station, Texas 77843-2117, USA.
Int J Food Microbiol. 2006 Jul 15;110(2):117-22. doi: 10.1016/j.ijfoodmicro.2006.01.041. Epub 2006 May 11.
The aim of this study was to identify a potential surrogate to describe the radiation sensitivity of the most common pathogens encountered in fruits. Three pathogens: Escherichia coli O157:H7 933, Listeria monocytogenes ATCC 51414, and Salmonella Poona, and five non-pathogens: E. coli K-12 MG1655, Listeria innocua Seeliger 1983 (NRRL B-33003 and NRRl B-33014), Enterobacter aerogenes, and Salmonella LT2 were inoculated (populations of 10(7)-10(9) CFU/ml) into model food systems (10% w/w gelatin) and exposed to doses up to 1.0 kGy using a 2 MeV Van der Graaf linear accelerator. The non-pathogen E. coli K-12 MG1655 was highly resistant to radiation (D(10)=0.88 kGy) in comparison to the other strains while L. monocytogenes was the more radiation-resistant pathogen (D(10)=1.09 kGy). Thus, E. coli K-12 MG1655 could be a suitable surrogate for e-beam studies with L. monocytogenes as the indicator pathogen. L. innocua strains were more radiation-sensitive (D(10)=0.66, 0.72 kGy) than their pathogenic counterpart. S. Poona and E. coli O157:H7 were even more radiation-sensitive (D(10)=0.38, 0.36 kGy, respectively). S. LT2 was the least radiation-resistant pathogen with D(10)=0.12 kGy. In a later study, the radiation resistance of the pathogens and the surrogate was evaluated when inoculated in a real food (i.e., fresh cantaloupe). The D(10) values obtained in this experiment were higher than those obtained with the model foods. However, the surrogate was still more radiation-resistant and could therefore be used to indicate decontamination of the target pathogens under electron beam irradiation.
本研究的目的是确定一种潜在的替代物，以描述水果中最常见病原体的辐射敏感性。将三种病原体：大肠杆菌O157:H7 933、单核细胞增生李斯特菌ATCC 51414和普纳沙门氏菌，以及五种非病原体：大肠杆菌K-12 MG1655、无害李斯特菌Seeliger 1983（NRRL B-33003和NRRl B-33014）、产气肠杆菌和沙门氏菌LT2（菌液浓度为10⁷-10⁹CFU/ml）接种到模型食品体系（10% w/w明胶）中，并用一台2 MeV的范德格拉夫直线加速器对其施加高达1.0 kGy的剂量。与其他菌株相比，非病原体大肠杆菌K-12 MG1655对辐射具有高度抗性（D₁₀=0.88 kGy），而单核细胞增生李斯特菌是更耐辐射的病原体（D₁₀=1.09 kGy）。因此，以单核细胞增生李斯特菌作为指示病原体进行电子束研究时，大肠杆菌K-12 MG1655可能是一种合适的替代物。无害李斯特菌菌株比其致病对应菌株对辐射更敏感（D₁₀=0.66、0.72 kGy）。普纳沙门氏菌和大肠杆菌O157:H7对辐射甚至更敏感（D₁₀分别为0.38、0.36 kGy）。沙门氏菌LT2是最不耐辐射的病原体，D₁₀=0.12 kGy。在后续研究中，对接种于真实食品（即新鲜哈密瓜）中的病原体和替代物的辐射抗性进行了评估。本实验中获得的D₁₀值高于在模型食品中获得的值。然而，替代物仍然更耐辐射，因此可用于指示电子束辐照下目标病原体的去污情况。
