Colonization and Internalization of Salmonella enterica in Tomato Plants

Abstract

bThe consumption of fresh tomatoes has been linked to numerous food-borne outbreaks involving various serovars of Salmonella enterica. Recent advances in our understanding of plant-microbe interactions have shown that human enteric pathogenic bacteria, including S. enterica, are adapted to survive in the plant environment. In this study, tomato plants (Solanum lycopersicum cv. Micro-Tom) grown in sandy loam soil from Virginia's eastern shore (VES) were inoculated with S. enterica serovars to evaluate plausible internalization routes and to determine if there is any niche fitness for certain serovars. Both infested soil and contaminated blossoms can lead to low internal levels of fruit contamination with Salmonella. Salmonella serovars demonstrated a great ability to survive in environments under tomato cultivation, not only in soil but also on different parts of the tomato plant. Of the five serovars investigated, Salmonella enterica serovars Newport and Javiana were dominant in sandy loam soil, while Salmonella enterica serovars Montevideo and Newport were more prevalent on leaves and blossoms. It was also observed that Salmonella enterica serovar Typhimurium had a poor rate of survival in all the plant parts examined here, suggesting that postharvest contamination routes are more likely in S. Typhimurium contamination of tomato fruit. Conversely, S. Newport was the most prevalent serovar recovered in both the tomato rhizosphere and phyllosphere. Plants that were recently transplanted (within 3 days) had an increase in observable internalized bacteria, suggesting that plants were more susceptible to internalization right after transplant. These findings suggest that the particular Salmonella serovar and the growth stage of the plant were important factors for internalization through the root system.

Occurrence of ingression of Salmonella spp. in Betel leaf (Piper betle L.)

“…into plant. Zheng et al (2013) also reported that Salmonella spp. has the ability to internalize into tomato plants through roots, leaves and blossoms.…”

“…Contamination can occur at any stage of production such as pre-harvest or post-harvest (Semenov et al 2010;Goldberg et al 2011;Bernstein 2011). Some recent studies reported internalization of bacteria into the plant part and subsequent translocation of bacteria to leaf and other aerial parts of the plant (Goldberg et al 2011;Zhuang et al 1995;Avila-Quezada et al 2010;Hirneisen et al 2012;Zheng et al 2013;Bernstein et al 2007a;Bernstein et al 2007b). This event is alarming due to the fact that internalization of pathogenic bacteria into fresh produce pose high risk to the consumers as they are significantly resistant to external biocidal washing agents (Ibarra-Sanchez et al 2004;Jablasone et al 2005;Donkor et al 2010).…”

Survey of Microbial Contamination of Tomatoes at Farms in Korea

“…내부로 침투할 능력이 있는 것으로 알려져 있다 9,10,11,12) . 또 한 Salmonella, E. coli O157:H7 등과 같은 병원성 미생물 이 과일 등에 오염이 된 후에는 세척 등으로 완전히 제거 하기가 어려우므로 13) , .…”

Microbial ecology of fresh vegetables

“…Several innovative approaches both chemically and physically have been explored for the decontamination of fresh or fresh-cut vegetables (Table 17.5). Effective washing and decontamination of fresh-cut veg etables is difficult to achieve due to the different types of vegetables, the inadequate efficacy of individual treatments alone (Table 17.5), the presence of biofilms on vegetables and on processing equipment (Jahid and Ha, 2012;Somers et al, 1994), and internalization/infil tration of bacteria within produce (Zhuang et al, 1995;Zheng et al, 2013;Takeuchi and Frank, 2000). Therefore, a combination of different disinfection methods (e.g., hurdle technology) (Rico et al, 2007;Joshi et al, 2013) is necessary to increase the efficacy of disinfectants against microbial population reduction.…”