Data from: Different food sources elicit fast changes to bacterial virulence

Environmentally transmitted, opportunistic bacterial pathogens have a life cycle that alternates between hosts and environmental reservoirs. Resources are often scarce and fluctuating in the outside-host environment, whereas overcoming the host immune system could allow pathogens to establish a new, resource abundant and stable niche within the host. We tested if shortterm exposure to different outside-host resource types and concentrations affect Serratia marcescens—(bacterium)’s virulence in Galleria mellonella (moth). As expected, virulence was mostly dictated by the bacterial dose, but we also found a clear increase in virulence when the bacterium had inhabited a low (versus high) resource concentration, or animal-based (versus plant-based) resources for 48 h prior to injection. The results suggest that temporal changes in pathogen’s resource environment can induce very rapid changes in virulence and affect infection severity. Such changes could also play an important role in shifts from environmental lifestyle to pathogenicity or switches in host range and have implications for the management of opportunistic pathogens and disease outbreaks.经环境传播的机会致病性细菌病原体，其生命周期在宿主与环境储库之间交替循环。宿主外环境中的资源往往稀缺且波动不定，而病原体若能突破宿主免疫系统，便可在宿主体内建立一个资源充沛且稳定的生态位。本研究探究了短期暴露于不同类型及浓度的宿主外资源，是否会影响粘质沙雷氏菌（Serratia marcescens，细菌）在大蜡螟（Galleria mellonella，蛾类）中的毒力。正如预期，毒力主要由细菌接种剂量决定；但我们同时发现，若细菌在注射接种前于低浓度（相较于高浓度）资源，或动物源性（相较于植物源性）资源中预培养48小时，其毒力会出现显著提升。研究结果表明，病原体所处资源环境的时间动态变化，可快速诱导毒力改变并影响感染严重程度。此类变化或在病原体从环境生活模式转向致病状态，或是宿主范围切换的过程中发挥关键作用，同时对机会致病性病原体的防控及疾病暴发管理具有重要指导意义。