Now you see them, now you don't - tracking hidden dormant bacteria in the environment

点击翻译按钮获取中文摘要

When you are in a deep sleep at night what wakes you up? Is it the sound of an alarm or the birds tweeting? Is it the smell of toast or coffee that stirs you awake? Do you wake up because your too hot or too cold? Or like me a tiny human wakes up and gets your attention. My research is about how bacteria enter a 'sleep-like' or 'hibernation-like' behaviour to ensure their survival in their environment and what cues they use to 'wake up' from this state of hibernation. Bacteria have clever ways to ensure they survive during periods of stress in their environment. These stresses may be a change in temperature, a lack of nutrients or it may come from antibiotic exposure or chlorination treatment. One-way bacteria survive the stress is by entering into a reversible state of dormancy. These dormant cells utilise nutrients at a reduced rate and change in size and shape to better protect themselves from unfavourable conditions. Furthermore, dormant cells are not detectable by routine tests making them difficult to study. They can stay in this 'sleep like' state until favourable conditions in the surrounding environment return, where they 'reawaken' and reproduce to cause bacterial blooms that are hazardous to the environment and in some cases human health. Scientists still do not know how bacteria are able to 'wake up' from this state of dormancy or what cues they use to change from a dormant state into an active growing population of cells.I will use Vibrio species found in the marine and estuarine environment to study bacterial dormancy. Vibrio species thrive in low salinity and warm temperatures and only appear in the environment during the warmer months. Vibrio bacteria are not detected in the winter, and it is assumed that the bacteria die due to the cold temperatures. However, a small proportion of the cells enter the dormant state to survive the winter conditions. When summer returns, nutrient levels and sea temperatures increase, and dormant Vibrio cells 'reawaken' and grow into bacterial populations. Recently, using advanced flow cytometry techniques, I was able to isolate Vibrio cells in the dormant phase from the environment, and wake them up into an active detectable population again. Using this ability to identify and manipulate dormant cells will for the first time, allow me to explore new conceptual territory in the field of bacterial dormancy.During this fellowship, I will collaborate with government agencies such as Cefas (UK) and Plant & Food Research Institute (New Zealand), seafood industry (Lyons Seafood), and international institutes (ICDDR,B, Institute of Marine Research (Norway), IZSUM (Italy), University of Barcelona, University of Alaska Fairbanks and George Mason University (USA)) to obtain environmental samples across the globe from areas where Vibrio species are abundant in the summer and thus likely to contain bacterial dormant cells during cooler months. I will uncover the geographical spread of dormant cells in the environment and whether they are present in specific niches, (e.g., sediment, water column, shellfish, oyster gut). I will look to see how dormant cells respond to changes in their environment, and identify the mechanistic processes that aid resuscitation of these dormant cells and allow them to re-emerge as a growing population. My research programme will lead to finding and developing new diagnostic tests to identify the presence of dormant bacteria early in the environment that will mitigate risks against emerging diseases from Vibrio bacteria worldwide.