Mikrobiologe Prof. Dr. Kai Papenfort ist Experte für "Quorum Sensing".

Chemical small talk – how bacteria calculate density

Kai Papenfort is the new Professor of General Microbiology. He is studying how microbes recognise members of their community
Microbiologist Prof. Dr Kai Papenfort is an expert in 'Quorum Sensing'.
Image: Anne Günther (University of Jena)
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Published: 7 February 2020, 09:32 | By: Ute Schönfelder

Cholera is a life-threatening disease, triggering stomach cramps, vomiting and severe diarrhoea. It is caused by the bacterium Vibrio cholerae, which usually finds its way into a person’s digestive system through contaminated drinking water. However, not every contact with V. cholerae automatically leads to a person falling ill with cholera. This only happens when a sufficiently large number of cholera pathogens have assembled to form a dense film. The pathogens then rapidly produce cholera toxin and the disease takes hold.

But how do the bacteria know whether their numbers are sufficient to overpower the host organism’s immune defence? “For this purpose, the pathogens use a kind of chemical counting mechanism,” says Professor Kai Papenfort of Friedrich Schiller University, Jena. “They produce signal molecules and release these into their environment,” explains the 38-year-old microbiologist, who moved to Jena from Ludwig Maximilian University of Munich this winter semester. As bacteria not only produce these molecules themselves, but can also sense them in their environment through receptors, they obtain information about the cell density of their population. The microbes regulate their behaviour according to their cell density and researchers call this form of chemical communication between microbial cells ‘Quorum Sensing’.

New concept for antibiotics

In his new laboratory on Jena’s Beutenberg Campus, Prof. Papenfort and his team are trying to decipher this type of chemical ‘small talk’ used by the cholera bacteria.


Our aim is not only to understand the bacteria when they communicate, but also to become actively involved in that communication.

Prof. Dr Kai Papenfort

If we could speak the microorganisms’ language, we could, for example, prevent the cholera bacteria from becoming virulent by fooling them into ‘thinking’ that they have not yet assembled enough other bacteria around them.” Papenfort is convinced that someone who has mastered the rules of ‘Quorum Sensing’ will have the possibility of developing a completely new concept for antibiotics. And not only against cholera. ‘Chemical persuasion’ could also be used to deter salmonellae, staphylococci or pseudomonads from triggering diseases.

Kai Papenfort brought the topic ‘Quorum Sensing’ from the USA, where he worked in Bonnie Bassler’s team at Princeton University from 2012 to 2015. Bassler is “a pioneer in this field”, according to Papenfort. Here in Jena, too, his fundamental research on microbial communication has already led him to find numerous starting points for further study. “With its Microverse Cluster of Excellence, the University of Jena is extremely well placed for this work,” he notes. Papenfort has also forged excellent scientific contacts with working groups at the Leibniz Institute for Natural Product Research and Infection Biology, which is in the immediate vicinity of the Beutenberg Campus. Outstanding conditions for lively exchanges – and not just for microbial communication.

In addition to the attraction of the strong microbiology research in Jena, the father of a young family was also persuaded to accept the position at Friedrich Schiller University because of the family-friendly environment in the town and at the University. “It was very important for me and my partner, who is also an academic and leads her own research group, to find good childcare here,” says Papenfort. The three-year-old now goes to the Beutenberg nursery, which is only a stone’s throw away from the institute.

Professional background

Kai Papenfort studied Biology in Marburg and his Master’s thesis already focused on microbiology and molecular biology. After his studies, he went to the Max Planck Institute for Infection Biology in Berlin, where he became familiar with what was then the completely new research field of regulatory RNAs. These RNAs, which control the genetic activity of bacteria, continue to be a further priority research area for Papenfort, not least because they also play a key role in ‘Quorum Sensing’. In 2010 he obtained his doctorate from Humboldt University in Berlin and then worked as a postdoc at the University of Würzburg, before moving to Princeton in 2012 with a grant from the Human Frontiers Science Program. He returned to Germany in 2015, first to Munich and now to Jena.

Prof. Papenfort has already obtained many grants and won several awards for his research, including a postdoctoral prize from the Robert Koch Foundation (2014), a Starting Grant from the European Research Council (2017) and as a Scholar of the Vallee Foundation (2019).


Kai Papenfort, Univ.-Prof. Dr
Hans-Knöll-Straße 2
07745 Jena
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