Impact of sanitizer application on Salmonella mitigation and microbiome shift on diced tomatoes during washing and storage

Salmonella enterica is a major foodborne pathogen associated with consumption of fresh tomatoes, and Salmonella contamination during post-harvest handling has been suspected and implicated in multiple food-borne illness outbreaks. This study examined the shift in Salmonella and indigenous microbiota on diced tomatoes after washing with different sanitizers and during storage. Roma tomatoes were inoculated with a Salmonella cocktail at 8 log CFU/mL, diced and washed along with non-inoculated diced tomatoes in simulated flume wash water with sanitizers, including 10 mg/L free chlorine (C10), 90 mg/L peracetic acid (P90), P90 plus a sulfuric acid surfactant (PP), and un-sanitized control (K). Salmonella, total bacteria, and yeast and mold (YM) populations on both inoculated and non-inoculated samples were measured before, after washing and during storage at 4 C. 16S rRNA high-throughput sequencing was also performed to determine shift in bacterial microbiome. Washing with all tested sanitizers, especially PP, efficiently reduced Salmonella and bacterial populations on inoculated diced tomatoes after washing. Application of sanitizers significantly mitigated Salmonella cross-contamination on non-inoculated samples. PP treatment inhibited the proliferation of most dominant bacteria on diced tomatoes during storage, such as Erwiniaceae, Curtobacterium, Pantoea, Erwinia and Enterobacterales, which may benefit product quality and safety. YM populations were generally similar among washing treatments with sanitizers. This study provides in-depth information about the microbial ecology of the diverse bacterial communities on diced tomatoes during washing and the subsequent storage, which can help guide further studies on the interactions of microbes on produce, the prevention of contamination with Salmonella, plant pathogens and spoilage bacteria.

Salmonella enterica作为一种重要的食源性病原体，与新鲜番茄的食用密切相关，且在收获后处理过程中疑似及被证实与多起食源性疾病爆发有关。本研究旨在探讨使用不同消毒剂清洗以及储存过程中，切块番茄上沙门氏菌及固有微生物群的变化。将罗玛番茄接种8对数CFU/mL的沙门氏菌混合液，与未接种的切块番茄一同在模拟水槽清洗水中加入消毒剂（包括10 mg/L游离氯（C10）、90 mg/L过乙酸（P90）、P90加硫酸盐表面活性剂（PP）以及未消毒对照组（K））进行清洗。在接种和未接种样本上，于清洗前后及4℃储存期间测量了沙门氏菌、总细菌数及酵母和霉菌（YM）的数量。此外，还进行了16S rRNA高通量测序，以确定细菌微生物组的变迁。所有测试的消毒剂，尤其是PP，在清洗后能有效降低接种切块番茄上的沙门氏菌和细菌数量。消毒剂的应用显著减轻了非接种样本上的沙门氏菌交叉污染。PP处理抑制了储存期间切块番茄上多数优势菌的生长，如Erwiniaceae、Curtobacterium、Pantoea、Erwinia和Enterobacterales，这可能有利于产品的质量和安全性。在添加消毒剂的清洗处理中，YM数量总体相似。本研究深入揭示了切块番茄在清洗及随后的储存过程中，多样细菌群落微生物生态学的信息，有助于指导微生物与农产品相互作用、预防沙门氏菌、植物病原菌和腐败菌污染等进一步的研究。