Microbiology Editor's Choice: signalling in the symbiotic life cycle

Posted on May 1, 2019   by Microbiology Society

Each month, a manuscript published in our flagship journal Microbiology is chosen by a member of the Editorial Board. This month, the paper is titled 'Iso-propyl stilbene: A life-cycle signal?' and was chosen by Professor Dave Kelly.

Members of the bioluminescent bacterial genus Photorhabdus have a complex life-cycle, being insect pathogens but also forming symbiotic associations with nematode worms. They produce a number of interesting secondary metabolites and unusual signalling molecules which are thought to be important in their life-cycle. In this article, the authors investigate the effects of one of these compounds, isopropyl stilbene (IPS), on the biology of Photorhabdus itself. IPS has anti-microbial activity but is also thought to be a signalling molecule. The authors demonstrate multiple phenotypic changes in response to IPS, including decreased bioluminescence and pigment production and a transcriptional down-regulation of central metabolic pathways and translation. Their results suggest a key role for IPS in quorum sensing, antimicrobial competition and signalling in the symbiotic state. The data in this paper will be of general interest to researchers interested in bacterial signalling mechanisms and molecules as well as those interested in bacterial symbioses in general. 

Iso-propyl stilbene: A life-cycle signal?

Stilbenoid compounds are normally produced by plants in response to infection and have important properties such as antimicrobial and antioxidant activities. Interestingly, Photorhabdus bacteria, which exist in symbiosis with insect-pathogenic nematode-worms, also produce stilbenoids. While these compounds do show good antibiotic activity against other bacteria, we demonstrate that they may also act as a signalling molecule for Photorhabdus bacteria themselves. Their stilbene triggers profound behavioural and gene expression changes in Photorhabdus, consistent with metabolic changes known to be required to facilitate symbiosis with the nematode worm partner. Thus, the stilbene appears to play a crucial role in the symbiotic life cycle. 

We spoke with corresponding author Alexia Hapeshi, to find out more about the research:

What is your institution and how long have you been there?

What is your research area? 

I am studying the mode of action of both synthetic and natural antimicrobial compounds.

What inspired you to research this topic? 

I became interested in microbiology early on during my undergraduate studies, when I conducted a research project in Professor George Salmond’s lab at the University of Cambridge. I have since worked on various aspects of bacteriology such as the virulence of pathogenic bacteria, metabolism and temperature restriction.

What is the most rewarding part of your research?

The most rewarding aspect of my research is the fact that we are tackling fundamental questions about biology while at the same time assisting in the development of new therapeutics. 

What would you be doing if you weren't a scientist?

I have not really considered a career outside science, but when I am not doing research I enjoy creating mosaics and painting!

You can follow the authors on Twitter: @AlexiaH4 @potentialbio @cleverflick @Nick_Waterfield