4.2. Phages to Control Industrially Relevant Biofilms
4.2.控制工业相关生物膜的噬菌体
The formation of biofilms in industrial settings represents a great challenge for industries, particularly the food industry. Biofilms tend to accumulate on surfaces in industrial settings, causing corrosion, loss of efficiency of certain equipment (e.g., heat exchangers), and contamination of food products. Chemical disinfection usually fails to efficiently sanitize food-contact surfaces where biofilms have accumulated, due to the high tolerance of biofilms to disinfection.
工业环境中生物膜的形成对各行各业，尤其是食品工业是一个巨大的挑战。生物膜往往积聚在工业环境的表面，造成腐蚀、某些设备（如热交换器）效率下降和食品污染。由于生物膜对消毒的耐受性很高，化学消毒通常无法有效地消毒生物膜积聚的食品接触表面。
4.2.1. Phages to control foodborne biofilms.
4.2.1.控制食源性生物膜的噬菌体。
Phage biocontrol is increasingly accepted as a natural and green technology for targeting bacterial pathogens in various foods and food-contact surfaces (122). Many phage preparations (e.g., ListShield™, Listex™ P100, EcoShield™, SalmoFresh™, Finalyse™) have been granted Generally Recognized as Safe designation by the Food and Drug Administration to be used as food additives and/or food-processing agents against many foodborne pathogens. These products have been tested on contaminated foods but not specifically on biofilms; nevertheless, it is most likely that they also have antibiofilm properties. It is noteworthy that Listex P100 and ListShield have been assessed for L. monocytogenes biofilm removal on different food-contact surfaces and lettuce, and promising results were reported (123–126). Biofilms formed by Salmonella, another important foodborne pathogen, have also been the subject of many phage biocontrol studies. For example, a cocktail of two phages proved to be very effective in removing Salmonella spp. biofilms from stainless steel, rubber, and lettuce surfaces (127). Another interesting example is the control of dual-species biofilms formed by Salmonella and E. coli (128). Milho et al. (128) observed that the biofilms formed by the two species were less susceptible to phage predation than the monospecies ones, raising awareness of the difficulty of controlling multispecies biofilms on industrial surfaces. González et al. (129) also characterized the interaction of an S. aureus phage with dual-species biofilms formed by combining the S. aureus host with different bacterial species. The results suggested that the effect of phage treatment on S. aureus mixed biofilms varies depending on the accompanying species and the infection conditions (129). These results highlight the need to study the effect of phage biocontrol on microbial communities that reflect more realistic conditions.
噬菌体生物防治作为一种针对各种食品和食品接触表面细菌病原体的天然绿色技术，已被越来越多的人接受 ( 122)。许多噬菌体制剂（例如，ListShield™、Listex™ P100、EcoShield™、SalmoFresh™、Finalyse™）已被食品和药物管理局授予 “公认安全 “称号，可用作食品添加剂和/或食品加工剂，以对付许多食源性病原体。这些产品已在受污染的食品上进行了测试，但没有专门针对生物膜进行测试；不过，它们很可能也具有抗生物膜的特性。值得注意的是，Listex P100 和 ListShield 已经在不同的食品接触表面和生菜上进行了单核细胞增生性酵母菌生物膜去除评估，并报告了良好的结果（123- 126）。沙门氏菌是另一种重要的食源性病原体，它形成的生物膜也是许多噬菌体生物控制研究的对象。例如，由两种噬菌体组成的鸡尾酒被证明能非常有效地清除不锈钢、橡胶和生菜表面的沙门氏菌生物膜 ( 127)。另一个有趣的例子是对沙门氏菌和大肠杆菌形成的双物种生物膜的控制 ( 128)。Milho 等人（128）观察到，与单菌种生物膜相比，这两种菌种形成的生物膜对噬菌体捕食的敏感性较低，这使人们意识到控制工业表面多菌种生物膜的难度。González 等人（129）也描述了金黄色葡萄球菌噬菌体与由金黄色葡萄球菌宿主和不同细菌物种结合形成的双物种生物膜之间的相互作用。结果表明，噬菌体处理对金黄色葡萄球菌混合生物膜的影响因伴随的菌种和感染条件而异 ( 129)。这些结果突出表明，有必要研究噬菌体生物控制对反映更真实条件的微生物群落的影响。
Phages did not always exhibit good killing properties against foodborne biofilms. Many studies have reported moderate to low killing efficacies that are not sufficient for an efficient surface sanitation. This is the case with a cocktail of three phages that failed to destroy established Vibrio parahaemolyticus biofilms (130). Nevertheless, the phages demonstrated a great ability to prevent biofilm formation (130). This feature is extensively reported in many phage-biofilm studies. Even if the phage is not able to reduce the cell population of a mature biofilm, it can prevent the biofilm from further proliferation (131). For example, Endersen et al. (132) demonstrated the successful use of a phage cocktail targeting Citrobacter sakazakii, an important pathogen involved in the contamination of infant formula, to prevent biofilm formation.
噬菌体对食源性生物膜的杀灭效果并不总是很好。许多研究报告称，噬菌体的杀灭效力为中等或较低，不足以实现有效的表面消毒。由三种噬菌体组成的鸡尾酒就未能破坏已形成的副溶血性弧菌生物膜（130）。不过，这些噬菌体在防止生物膜形成方面表现出很强的能力 ( 130)。许多噬菌体-生物膜研究都广泛报道了这一特点。即使噬菌体不能减少成熟生物膜的细胞数量，它也能阻止生物膜进一步增殖 ( 131)。例如，Endersen 等人 ( 132) 成功地利用针对阪崎柠檬酸杆菌的鸡尾酒噬菌体阻止了生物膜的形成，阪崎柠檬酸杆菌是造成婴儿配方奶粉污染的重要病原体。
Several strategies have been suggested to improve phage efficacy against foodborne biofilms. As described previously for clinical purposes, the use of a cocktail of phages against foodborne biofilms is also highly recommended to limit the emergence of BIMs. Other strategies are based on the combination of phages with other sanitizing agents (that do not inactivate phages) (133, 134) or essential oils (135). An interesting work by Li et al. (136) demonstrated the potential of using phages attached to magnetic colloidal nanoparticle clusters that facilitate biofilm penetration under a relatively small magnetic field, which led to approximately 90% biofilm removal of P. aeruginosa and E. coli biofilms within 6 h of treatment.
有几种策略可以提高噬菌体对食源性生物膜的疗效。如前所述，为临床目的，强烈建议使用鸡尾酒噬菌体来对付食源性生物膜，以限制 BIM 的出现。其他策略是将噬菌体与其他消毒剂（不会使噬菌体失活）（133、134）或精油（135）结合使用。Li 等人（136）的一项有趣研究表明，在相对较小的磁场下，噬菌体附着在磁性胶体纳米粒子团簇上可促进生物膜的穿透，从而在 6 小时的处理时间内清除约 90% 的铜绿假单胞菌和大肠杆菌生物膜。