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Karina B. Xavier Lab


In our laboratory we to study a process called Quorum Sensing which enables bacteria to synchronize their behaviour and act in group to regulate important processes such as virulence, biofilm formation and antibiotics production.  



Karina B. Xavier
Investigador Auxiliar
PhD in 1999, Universidade Nova de Lisboa (ITQB)

Phone (+351) 214464655


Research Interests

Bacteria use small chemical molecules called autoinducers to communicate with one another by a process called quorum sensing. This process enables a population of bacteria to regulate behaviours which are only productive when many bacteria act in concert as a group, similarly to what happens with multi-cellular organisms. Behaviours regulated by quorum sensing include production of virulence factors, formation of biofilms, and synthesis of secondary metabolites like antibiotics. Importantly, these processes are often crucial for successful bacterial-host relationships whether symbiotic and pathogenic. In the Bacterial Signalling laboratory we combine biochemical and genetic approaches from molecules to circuits to understand how the molecular mechanisms underlying quorum sensing regulate bacterial behaviours. 

Most Quorum Sensing systems studied to date rely on autoinducers signals which are species-specific and therefore promote intra-species cell-cell comunication. However, in nature most bacteria live in poly-microbial species communities and thus it is expected that inter-species signal interactions between the community members are important. Thus in our laboratory we focus in Quorum Sensing systems which can promote bacterial inter-species communication. One of these systems relies on one autoinducer termed AI-2 which is produced and detected by a wide variety of bacterial species. Our research includes an integrated study involving elucidation of new chemical molecules that are used as inter-species signals, the network components involved in detecting the signals and processing information inside individual cells, and finally characterization of the behaviour of the bacterial community in multi-species bacterial consortia. Our ultimate goal is to understand how bacteria use inter-species cell-cell communication to coordinate population-wide behaviours in consortia and in microbial-host interactions. These studies can lead to the development of new therapies to control functions regulated by quorum sensing, such as virulence, and also to develop biotechnological applications to control industrial scale production of beneficial bacterial products, like antibiotics or recombinant proteins.

NOTE: AI-2 and related compounds are available for sale.


Group Members

  • Jessica Thompson, Postdoc
  • Pol Nadal, Postdoc
  • Rita Valente, PhD Student
  • Ozhan Ozkaya, PhD Student
  • Ana Rita Oliveira, Junior Research Fellow
  • Paulo Correia, Junior Research Fellow
  • Jorge M. Pereira, Master Student


Selected Publications

  1. Pereira, C. S., Thompson, J. A., Xavier, K.B. 2012. AI-2-mediated signalling in bacteria. FEMS Microbiol Rev. doi: 10.1111/j.1574-6976.2012.00345.x. [Epub ahead of print]
  2. Pereira, C. S., Santos, A. J. M., Bejerano-Sagie, M., Correia, P. B., Marques, J. C., and Xavier, K. B. 2012. Phosphoenolpyruvate Phosphotransferase System regulates detection and processing of the quorum sensing signal Autoinducer-2. Mol. Micro. 84:93-104.
  3. Xavier, K. B. and Bassler, B. L. 2005. Interference with AI-2-mediated bacterial cell-cell communication. Nature. 437: 750-53.


Laboratory's Website

For further information please visit the laboratory's website 


Comunicação Celular Bacteriana (PT)

As bactérias comunicam entre si usando pequenas moléculas químicas por um processo denominado “detecção de quórum”. Este mecanismo permite que uma população bacteriana regule determinados comportamentos de uma forma sincronizada como se tratasse de um organismo multi-celular. Neste projecto pretende-se utilizar uma abordagem multidisciplinar para compreender como é que as bactérias usam estes sistemas de comunicação para coordenar comportamentos de grupos em consórcios de multi-espécies e a importância destes mecanismos em interacções bactéria-hospedeiro.
Este tipo de estudos podem contribuir para o desenvolvimento de novas terapias para controlar funções reguladas por sistemas de “detecção de quórum”, como a virulência, e também para aplicações biotecnológicas que permitam o controlo da síntese de produtos bacterianos benéficos, como antibióticos e proteínas de interesse industrial.


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