U.S. Department of Agriculture, Agricultural Research Service, U.S. Meat Animal Research Center, P. O. Box 166, State Spur 18D, Clay Center, Nebraska 68933 (ORCID: https://orcid.org/0000-0003-1924-3275 [R.W.]; https://orcid.org/0000-0001-8060-4645 [N.K.]; https://orcid.org/0000-0002-7203-8951 [D.M.H.]; https://orcid.org/0000-0002-6571-9097 [T.L.W.]).
Center for Biotechnology, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA (ORCID: https://orcid.org/0000-0002-9783-1868 [Y.Z.]).
J Food Prot. 2021 Mar 1;84(3):408-417. doi: 10.4315/JFP-20-321.
Many foodborne pathogens, including Escherichia coli O157:H7 and Salmonella enterica, can develop biofilms on contact surfaces at meat processing plants. Owing to the high tolerance of the biofilm cells associated with the three-dimensional biofilm structure and the well-expressed bacterial extracellular polymeric substances, it is a real challenge to completely inactivate and remove mature biofilms, as well as further prevent biofilm reoccurrence and pathogen survival. In the present study, we evaluated the effectiveness of consecutive treatments (10 to 120 min per treatment) by repeatedly applying a multicomponent sanitizer, based on a functional mechanism by synergistic combination of hydrogen peroxide and quaternary ammonia compounds, against biofilms formed by E. coli O157:H7 and S. enterica strains. Biofilms on stainless steel surfaces were treated with 2.5, 5, or 10% (recommended working concentration) of the sanitizer applied as a foam or liquid solution. Our results showed that the multicomponent sanitizer significantly (P < 0.05) reduced the amount of viable biofilm cells at all concentrations, as enumerable bacteria were only detected after low-concentration treatments (2.5 or 5%) with short exposure periods (10 or 20 min per treatment). Treatments with high concentrations (5 or 10%) of the sanitizer, multiple consecutive treatments (2 or 3 treatments), and sufficient exposure time (>60 min per treatment) effectively controlled pathogen survival postsanitization. Examination with a scanning electron microscope showed that treatment with the sanitizer at 5% strength significantly dissolved the connecting extracellular polysaccharide matrix and removed the majority of the biofilm matrix. No intact biofilm structure was detected after the 10% sanitizer treatment; instead, scattered individual bacteria with visibly altered cell morphology were observed. The treated bacteria exhibited indented and distorted shapes with shortened cell length and increased surface roughness, indicating severe cell injury and death. Our observations indicated that consecutive treatments with the multicomponent sanitizer was effective in inactivating E. coli O157:H7 and S. enterica biofilms and preventing pathogen reoccurrence.
许多食源性致病菌，包括大肠杆菌 O157:H7 和沙门氏菌，都可以在肉类加工厂的接触表面形成生物膜。由于与三维生物膜结构相关的生物膜细胞的高耐受性和细菌胞外聚合物的良好表达，完全灭活和去除成熟生物膜以及进一步防止生物膜再发生和病原体存活是一个真正的挑战。在本研究中，我们评估了通过反复应用基于过氧化氢和季铵化合物协同组合的功能机制的多组分消毒剂，对大肠杆菌 O157:H7 和沙门氏菌菌株形成的生物膜进行连续处理（每次处理 10 至 120 分钟）的有效性。不锈钢表面上的生物膜用 2.5%、5%或 10%（推荐工作浓度）的消毒剂处理，消毒剂以泡沫或液体溶液的形式使用。我们的结果表明，多组分消毒剂在所有浓度下均显著（P<0.05）减少了可培养生物膜细胞的数量，因为只有在低浓度处理（2.5%或 5%）和短暴露时间（每次处理 10 或 20 分钟）后才能检测到可计数的细菌。消毒剂高浓度（5%或 10%）、多次连续处理（2 或 3 次处理）和足够的暴露时间（每次处理>60 分钟）有效控制了消毒后的病原体存活。扫描电子显微镜检查表明，用 5%强度的消毒剂处理可显著溶解连接的胞外多糖基质并去除大部分生物膜基质。用 10%消毒剂处理后未检测到完整的生物膜结构；相反，观察到大量形态发生明显改变的分散单个细菌。处理后的细菌表现出凹陷和扭曲的形状，细胞长度缩短，表面粗糙度增加，表明细胞严重损伤和死亡。我们的观察表明，用多组分消毒剂进行连续处理可有效灭活大肠杆菌 O157:H7 和沙门氏菌生物膜并防止病原体再发生。
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