Microbiology and Marine Product Technology Group (MICROTEC), Marine Research Institute (IIM), Department of Food Technology, CSIC, Vigo, Spain.
Microbiology and Marine Product Technology Group (MICROTEC), Marine Research Institute (IIM), Department of Food Technology, CSIC, Vigo, Spain.
Int J Food Microbiol. 2022 Sep 2;376:109773. doi: 10.1016/j.ijfoodmicro.2022.109773. Epub 2022 Jun 4.
In nature, bacterial pathogens like L. monocytogenes, live in nature associated with other microbial species in spatially-structured communities called biofilms. In the food industry, biofilms contribute to the survival and persistence of L. monocytogenes within processing facilities, thereby enhancing its risk of cross-contaminating food products. The challenge of combating biofilms has triggered the search for new antibiofilm strategies including devising ways to interfere with cell communication mechanisms (quorum-sensing) that are known to be involved with biofilm development regulation. The aim of this study was to explore cell communication signals in a L. monocytogenes-carrying microbial community isolated from a meat processing plant (location No. 96) in order to elucidate the ecological interactions that could serve as a starting point for the development of new antibiofilm strategies. Quorum quenching (QQ) and quorum sensing (QS) activities were screened among 31 bacterial strains isolated from location No. 96. Whereas no QQ activity was detected against short-chain lactone N-hexanoyl-DL-homoserine lactone (C6-HSL), it was detected against N-dodecanoyl-DL-homoserine lactone (C12-HSL) in 7 isolates (23%), particularly in Pseudomonas monteilli, Rhodococcus sp. and Rhodococcus erythropolis. QS activity assays detected HC4, C4, C6, OC6, HC10 and C16 in all the extracts, being C4, C6 and OC6 with predominantly produced by Pseudomonas monteilli, Pseudomonas gesardii, Psychrobacter maritimus and Paracoccus sp. High production levels of C16-HSL by Paracoccus sp. and the role of this long-chain lactone as a self-inhibitor of cell aggregation led us to carry out further studies focused on the effects of a Paracoccus lactone extract (PLE) against the biofilm formation by L. monocytogenes. A quantitative microscopic analysis demonstrated a significant decrease (p < 0.05) in the area occupied by biofilms formed on stainless steel (SS) coupons by different strains of L. monocytogenes in the presence of PLEs. Conversely, no significant differences were observed in the total number of viable adhered cells on SS coupons with or without PLE. The observed effect was partially reproduced by the addition of pure C16-HSL to 24 h-biofilms of L. monocytogenes L1.96. These results demonstrate that the observed effects can be attributed, at least partially, to the HSLs contained in the PLE. Overall, the present results highlight how interspecies communication within a biofilm can open up new insights for the development of new ways to combat biofilm.
在自然界中，像李斯特菌（L. monocytogenes）这样的细菌病原体与其他微生物物种一起存在于空间结构的群落中，称为生物膜。在食品工业中，生物膜有助于李斯特菌在加工设施内的存活和持续存在，从而增加其交叉污染食品产品的风险。与生物膜作斗争的挑战引发了人们对新的抗生物膜策略的探索，包括设计干扰细胞通讯机制（群体感应）的方法，因为已知这些机制与生物膜发育调节有关。本研究的目的是探索从肉类加工厂（位置 96）分离出的携带李斯特菌的微生物群落中的细胞通讯信号，以阐明可能成为开发新的抗生物膜策略起点的生态相互作用。在从位置 96 分离出的 31 株细菌中筛选了群体感应（QS）和群体淬灭（QQ）活性。虽然没有检测到针对短链内酯 N-己酰基-DL-高丝氨酸内酯（C6-HSL）的 QQ 活性，但在 7 株（23%）细菌中检测到针对 N-十二酰基-DL-高丝氨酸内酯（C12-HSL）的 QQ 活性，特别是在假单胞菌属、红球菌属和红游动菌属中。所有提取物中均检测到 HC4、C4、C6、OC6、HC10 和 C16 的 QS 活性测定，其中 C4、C6 和 OC6 主要由假单胞菌属、恶臭假单胞菌、海栖嗜冷杆菌和副球菌属产生。副球菌属高产量的 C16-HSL 及其作为细胞聚集自抑制剂的作用，促使我们进一步研究副球菌属内酯提取物（PLE）对李斯特菌生物膜形成的影响。定量显微镜分析表明，在存在 PLE 的情况下，不同李斯特菌菌株在不锈钢（SS）片上形成的生物膜的面积显著减少（p<0.05）。相反，在有无 PLE 的情况下，SS 片上附着的存活细胞总数没有显著差异。将纯 C16-HSL 添加到李斯特菌 L1.96 的 24 小时生物膜中，部分再现了观察到的效果。这些结果表明，观察到的效果至少部分归因于 PLE 中含有的 HSL。总的来说，本研究结果强调了生物膜内种间通讯如何为开发新的抗生物膜方法提供新的见解。
