Flanders Research Institute for Agriculture, Fisheries and Food (ILVO), Technology and Food Science Unit, Brusselsesteenweg 370, 9090, Melle, Belgium.
Faculty of Bioscience Engineering, Department of Microbial and Molecular Systems (M2S), Centre of Microbial and Plant Genetics (CMPG), University of Leuven, Kasteelpark Arenberg 20 box 2460, 3001, Leuven, Belgium.
BMC Microbiol. 2020 Dec 11;20(1):373. doi: 10.1186/s12866-020-02046-5.
Environmental biofilms can induce attachment and protection of other microorganisms including pathogens, but can also prevent them from invasion and colonization. This opens the possibility for so-called biocontrol strategies, wherein microorganisms are applied to control the presence of other microbes. The potential for both positive and negative interactions between microbes, however, raises the need for in depth characterization of the sociobiology of candidate biocontrol agents (BCAs). The inside of the drinking water system (DWS) of broiler houses is an interesting niche to apply BCAs, because contamination of these systems with pathogens plays an important role in the infection of broiler chickens and consequently humans. In this study, Pseudomonas putida, which is part of the natural microbiota in the DWS of broiler houses, was evaluated as BCA against the broiler pathogen Salmonella Java.
To study the interaction between these species, an in vitro model was developed simulating biofilm formation in the drinking water system of broilers. Dual-species biofilms of P. putida strains P1, P2, and P3 with S. Java were characterized by competitive interactions, independent of P. putida strain, S. Java inoculum density and application order. When equal inocula of S. Java and P. putida strains P1 or P3 were simultaneously applied, the interaction was characterized by mutual inhibition, whereas P. putida strain P2 showed an exploitation of S. Java. Lowering the inoculum density of S. Java changed the interaction with P. putida strain P3 also into an exploitation of S. Java. A further increase in S. Java inhibition was established by P. putida strain P3 forming a mature biofilm before applying S. Java.
This study provides the first results showing the potential of P. putida as BCA against S. Java in the broiler environment. Future work should include more complex microbial communities residing in the DWS, additional Salmonella strains as well as chemicals typically used to clean and disinfect the system.
环境生物膜可以诱导其他微生物（包括病原体）的附着和保护，但也可以防止它们入侵和定植。这为所谓的生物防治策略提供了可能性，即在生物防治剂中应用微生物来控制其他微生物的存在。然而，微生物之间存在积极和消极相互作用的可能性，这就需要深入研究候选生物防治剂（BCA）的社会生物学。肉鸡舍饮用水系统（DWS）内部是应用 BCA 的一个有趣生态位，因为这些系统受到病原体的污染在肉鸡和人类感染中起着重要作用。在这项研究中，假单胞菌（Pseudomonas putida）被评估为针对肉鸡病原体沙门氏菌（Salmonella Java）的 BCA，它是肉鸡舍 DWS 自然微生物群的一部分。
为了研究这些物种之间的相互作用，开发了一种体外模型来模拟肉鸡饮用水系统中的生物膜形成。用 P. putida 菌株 P1、P2 和 P3 与 S. Java 形成的双物种生物膜的特征是竞争相互作用，与 P. putida 菌株无关，与 S. Java 接种密度和应用顺序无关。当等量的 S. Java 和 P. putida 菌株 P1 或 P3 同时接种时，相互作用的特征是相互抑制，而 P. putida 菌株 P2 则表现出对 S. Java 的利用。降低 S. Java 的接种密度也使 P. putida 菌株 P3 与 S. Java 的相互作用变为对 S. Java 的利用。当 P. putida 菌株 P3 在应用 S. Java 之前形成成熟的生物膜时，S. Java 的抑制作用进一步增加。
本研究首次提供了 P. putida 作为肉鸡环境中针对 S. Java 的 BCA 的潜力的结果。未来的工作应包括居住在 DWS 中的更复杂的微生物群落、其他沙门氏菌菌株以及通常用于清洁和消毒系统的化学品。
