Lapidot Anat, Romling Ute, Yaron Sima
Department of Biotechnology and Food Engineering, Technion, Haifa, Israel.
Int J Food Microbiol. 2006 Jun 15;109(3):229-33. doi: 10.1016/j.ijfoodmicro.2006.01.012. Epub 2006 Apr 17.
Although several studies provide evidence that the formation of biofilms by human pathogens on plant tissue is possible, to date there is no direct evidence that biofilms enhance the resistance of plant-associated pathogens to disinfectants or biocides. We hypothesized that biofilm formation would enhance the adhesion and survival of Salmonella on leafy vegetables. To test our hypothesis, we compared the adhesion and persistence of Salmonella Typhimurium and its biofilm-deficient isogenic mutant. Following inoculation of parsley and rinsing with water or chlorine solution, both strains had similar survival properties, and up to 3-log reduction were observed, depending on chlorine concentration. This indicates that the biofilm matrix of Salmonella likely does not play a significant role in initial adhesion and survival after disinfection. After a week of storage the biofilm producing strain survived chlorination significantly better than the biofilm-deficient mutant. However, the recovery of the mutant was still elevated, indicating that although the biofilm matrix has a role in persistence of Salmonella after chlorination treatment of parsley, this is not the most important mechanism, and other mechanisms, probably the ability to penetrate the plant tissue or the pre-existing biofilms, or production of different polysaccharides other than cellulose, provide the protection.
尽管多项研究提供了证据表明人类病原体在植物组织上形成生物膜是可能的，但迄今为止，尚无直接证据表明生物膜会增强与植物相关的病原体对消毒剂或杀菌剂的抗性。我们推测生物膜的形成会增强沙门氏菌在叶菜类蔬菜上的附着力和存活率。为了验证我们的推测，我们比较了鼠伤寒沙门氏菌及其生物膜缺陷型同基因突变体的附着力和持久性。在接种欧芹并用清水或氯溶液冲洗后，两种菌株具有相似的存活特性，根据氯浓度的不同，观察到高达3个对数级的减少。这表明沙门氏菌的生物膜基质可能在消毒后的初始附着力和存活中不起重要作用。储存一周后，产生生物膜的菌株在氯化处理后存活得明显比生物膜缺陷型突变体好。然而，突变体的回收率仍然很高，这表明尽管生物膜基质在欧芹氯化处理后沙门氏菌的持久性中起作用，但这不是最重要的机制，其他机制，可能是穿透植物组织的能力、预先存在的生物膜，或产生除纤维素以外的不同多糖，提供了保护作用。
