Department of Food Science, Rutgers University, New Brunswick, NJ 08901, USA.
Department of Food Science, Rutgers University, New Brunswick, NJ 08901, USA.
Food Res Int. 2018 Jun;108:35-41. doi: 10.1016/j.foodres.2018.03.029. Epub 2018 Mar 11.
Shiga toxin-producing Escherichia coli (STEC) has been associated with illnesses and outbreaks linked to fresh vegetables, prompting a growing public health concern. Most studies regarding interactions of STEC on fresh produce focused on E. coli O157:H7. Limited information is available about survival or fitness of E. coli O104:H4, non-O157 pathogen that was linked to one of the largest outbreaks of hemolytic uremic syndrome in 2011. In this study, survival of E. coli O104:H4 was evaluated on Arabidopsis thaliana plant and lettuce for 5 days compared with E. coli O157:H7, and expression of pathogenesis-realted gene (PR1; induction of plant defense response) was examined by reverse transcription quantitative PCR, and potential influence of capsular polysaccharide (CPS) on the bacterial fitness on plant was investigated. Populations of E. coli O104:H4 strains (RG1, C3493, and LpfA) on Arabidopsis and lettuce were significantly (P < 0.05) greater than those of E. coli O157:H7 strains (7386 and sakai) at day 5 post-inoculation, indicating E. coli O104:H4 may have better survival ability on the plants. In addition, the E. coli O104:H4 strains produced significantly (P < 0.05) higher amounts of CPS compared with the E. coli O157:H7 strains. RG1 strain (1.5-fold) initiated significantly (P < 0.05) lower expression of PR1 gene indicating induction of plant defense response compared with E. coli O157:H7 strains 7386 (2.9-fold) and sakai (2.7-fold). Collectively, the results in this study suggests that different level of CPS production and plant defense response initiated by each STEC strain might influence the bacterial survival or persistence on plants. The present study provides better understanding of survival behavior of STEC, particularly E. coli O104:H4, using a model plant and vegetable under pre-harvest conditions with plant defense response.
产志贺毒素大肠杆菌（STEC）与与新鲜蔬菜有关的疾病和疫情有关，引起了公众健康的日益关注。大多数关于 STEC 对新鲜农产品相互作用的研究都集中在大肠杆菌 O157:H7 上。有关非 O157 病原体大肠杆菌 O104:H4 的存活或适应性的信息有限，该病原体与 2011 年最大的溶血性尿毒症综合征疫情之一有关。在这项研究中，与大肠杆菌 O157:H7 相比，评估了大肠杆菌 O104:H4 在拟南芥植物和生菜上的存活情况，为期 5 天，并通过反转录定量 PCR 检查了与发病机理相关的基因（PR1；诱导植物防御反应）的表达，研究了荚膜多糖（CPS）对细菌在植物上适应性的潜在影响。在接种后第 5 天，大肠杆菌 O104:H4 菌株（RG1、C3493 和 LpfA）在拟南芥和生菜上的种群数量明显（P<0.05）高于大肠杆菌 O157:H7 菌株（7386 和 sakai），表明大肠杆菌 O104:H4 可能在植物上具有更好的生存能力。此外，大肠杆菌 O104:H4 菌株比大肠杆菌 O157:H7 菌株产生的 CPS 量明显更高（P<0.05）。与大肠杆菌 O157:H7 菌株 7386（2.9 倍）和 sakai（2.7 倍）相比，RG1 菌株（1.5 倍）启动的 PR1 基因表达明显（P<0.05）较低，表明诱导了植物防御反应。总的来说，本研究表明，每个 STEC 菌株产生的 CPS 水平和引发的植物防御反应的不同可能会影响细菌在植物上的生存或持久性。本研究通过使用模型植物和蔬菜在收获前条件下并考虑植物防御反应，更好地了解了 STEC 特别是大肠杆菌 O104:H4 的生存行为。
