Marvasi Massimiliano, Hochmuth George J, Giurcanu Mihai C, George Andrée S, Noel Jason T, Bartz Jerry, Teplitski Max
Department of Soil and Water Science, University of Florida, Gainesville, Florida, United States of America.
PLoS One. 2013 Dec 4;8(12):e80871. doi: 10.1371/journal.pone.0080871. eCollection 2013.
Fresh fruits and vegetables become increasingly recognized as vehicles of human salmonellosis. Physiological, ecological, and environmental factors are all thought to contribute to the ability of Salmonella to colonize fruits and vegetables pre- and post-harvest. The goal of this study was to test how irrigation levels, fruit water congestion, crop and pathogen genotypes affect the ability of Salmonella to multiply in tomatoes post-harvest.
Fruits from three tomato varieties, grown over three production seasons in two Florida locations, were infected with seven strains of Salmonella and their ability to multiply post-harvest in field-grown tomatoes was tested. The field experiments were set up as a two-factor factorial split plot experiment, with the whole-plot treatments arranged in a randomized complete-block design. The irrigation treatment (at three levels) was the whole-plot factor, and the split-plot factor was tomato variety, with three levels. The significance of the main, two-way, and three-way interaction effects was tested using the (type III) F-tests for fixed effects. Mean separation for each significant fixed effect in the model was performed using Tukey's multiple comparison testing procedure.
The irrigation regime per se did not affect susceptibility of the crop to post-harvest proliferation of Salmonella. However, Salmonella grew significantly better in water-congested tissues of green tomatoes. Tomato maturity and genotype, Salmonella genotype, and inter-seasonal differences were the strongest factors affecting proliferation. Red ripe tomatoes were significantly and consistently more conducive to proliferation of Salmonella. Tomatoes harvested in the driest, sunniest season were the most conducive to post-harvest proliferation of the pathogen. Statistically significant interactions between production conditions affected post-harvest susceptibility of the crop to the pathogen. UV irradiation of tomatoes post-harvest promoted Salmonella growth.
新鲜水果和蔬菜越来越被认为是人类沙门氏菌病的传播媒介。生理、生态和环境因素都被认为有助于沙门氏菌在收获前和收获后在水果和蔬菜上定殖的能力。本研究的目的是测试灌溉水平、果实水分含量、作物和病原体基因型如何影响沙门氏菌在收获后番茄中的繁殖能力。
在佛罗里达州的两个地点，三个番茄品种在三个生产季节种植的果实，用七种沙门氏菌菌株进行感染，并测试它们在收获后在田间种植的番茄中的繁殖能力。田间试验设置为两因素析因裂区试验，全区处理采用随机完全区组设计。灌溉处理（三个水平）是全区因素，裂区因素是番茄品种，有三个水平。使用固定效应的（III型）F检验来检验主要、双向和三向交互效应的显著性。模型中每个显著固定效应的均值分离采用Tukey多重比较检验程序进行。
灌溉制度本身并不影响作物对收获后沙门氏菌增殖的易感性。然而，沙门氏菌在未成熟绿番茄水分含量高的组织中生长得明显更好。番茄成熟度和基因型、沙门氏菌基因型以及季节间差异是影响增殖的最强因素。成熟的红番茄显著且持续地更有利于沙门氏菌的增殖。在最干燥、阳光最充足的季节收获的番茄最有利于病原体收获后的增殖。生产条件之间具有统计学意义的相互作用影响了作物收获后对病原体的易感性。收获后对番茄进行紫外线照射促进了沙门氏菌的生长。
