#FEMSmicroBlog: A leader bacterium starting a new growth phase


The growth of bacteria has been fascinating researchers for many years. When adapting to a new environment, bacteria take some time before they start dividing and multiplying again. The study “A leader cell triggers end of lag phase in populations of Pseudomonas fluorescens” in microLife now looks at how bacteria decide to end the lag phase and resume cell division. In a #BehindThePaper Interview, Paul Rainey explains what this knowledge means for our understanding of bacterial growth. #FEMSmicroBlog


Can you summarise the significance of your paper for microbiologists outside of your field?

Our study A leader cell triggers end of lag phase in populations of Pseudomonas fluorescens” in microLife concerns a fundamental aspect of bacterial growth. The question of how bacteria resume growth following the period of non-growth in the lag phase has a history going back more than 100 years.

What we show is that — at least in small volumes — the time for populations to resume growth depends on the number of so-called founding cells. If there are a few cells, then the time for resumption of growth is long. But when populations are founded by thousands of cells, growth resumes much more rapidly. This is known as the inoculum effect.

Other than providing highly quantitative insights into the phenomenon, of our study showed that growth is triggered by the activity of a single “leader” cell. This evidence stems from using new millifluidic technologies combined with statistical physics approaches. Millifluidics allowed us to precisely control the numbers of cells founding new populations and permitted high levels of replication.

Bacterial population growth in droplets.
Bacterial population growth in droplets. From Ardré et al. (2022).


What can non-scientists or society learn from your research results?

We now know that the end of the lag phase highly depends on the interactions between the bacterial cells with the one “leader cell”. This interaction triggers the end of the lag phase for the whole bacterial community. Next, research should focus on understanding the molecular details of this mechanism.

Knowledge about the involved factors or proteins would help us find new targets for antimicrobial compounds to prevent bacteria from resuming their growth or slow it down. This would have clear relevance to infection biology and would help control microbes responsible for food-spoilage. Such knowledge is also important in modelling growth of microbes in numerous contexts.

Why did you choose to dive into the topic of this paper? What fascinates you about bacterial growth?

The long standing problems of fundamental nature have always attracted me. If one stops and thinks about lag phase – the phase of non-growth that bacteria encounter when transferred to fresh media – then many questions arise.

Why should bacteria cease growth when conditions are seemingly optimal? Is this an adaptive strategy or is it an unintended consequence of changes in cell physiology? But of particular interest to us was the control of exiting this non-growing state.


Why did you choose the Academy Submission Route and what are the benefits in your opinion?

Obtaining good quality reviews is an increasing problem. The publication process is overwhelmed by the high numbers of papers and journals. Hence, the burden on scientists to act as reviewers is really problematic.

By inviting reviews from respected peers, one ensures real engagement by referees in the reviewing process. After all, their identity is known, so one can assume that they are therefore highly motivated to put real effort into the reviewing process. I’ve rarely received such valuable criticism from reviewers and would not hesitate to use the Academy Submission Route in the future.

About this blog section

#BehindThePaper posts on the #FEMSmicroBlog aim to bring science closer to different audiences and to tell more about the scientific or personal journey to come to the results.

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