Authors: Jozsef Farkas and Csilla Mohacsi-Farkas
Contrary with past considerations, bacteria are highly versatile beings. They are able to communicate not only within their community but interspecies, and eventually to higher plants and animals. They are producing specific signalling molecules inducing various gene expressions in other beings. This chemical communication is called quorum sensing. The lecture summarizes some recent information on this “social” behaviour of bacteria, particularly on its role in biofilms, food spoilage and food-related pathogenesis. Recent findings show that medically important antibiotics evolved in the nature not only to kill competitors but for communication. It is important to develop methods for detecting the signalling molecules and to understand better the quorum sensing inhibitors to develop new tools for enhancing food preservation and food safety.
The Dutch Anton van Leeuwenhoek was the first observer of the tiny bacteria nearly three hundred and forty years ago. It is known today that bacteria are not only the most ancient but also the most abundant beings on the Earth. These single-celled organisms are also the major actors in food microbiology. The French Louis Pasteur and the German Robert Koch, great scientists of the second half of the 19th century have laid the foundation of microbiology by making essential discoveries and developing fundamental methods resulting in the scientific explanation of food spoilage and many diseases (establishing the so-called “germ-theory”). Due to the farreaching effects of their research, bacteria were regarded for long time as self- sufficient individuals making strictly unicellular life style and creating a single cause - single effect situation.
This paradigm was accepted both in the food and medical sciences. However, mainly because the consequence of developments in the disciplines of microbial ecology and molecular biology during the second half of the 20th century, this type of former scientific approach is changing in the direction of studies for more deeper understanding of microbial communities. These developments resulted in the recognition, how sophisticated are apparently simple bacteria. It turned out that they are not simply existing together in various forms with other beings, but they are communicating between each other as well as with other species, or, even with higher plants and animals.
This communication means in its most well-known form the production and emission of specific organic molecules (“autoinducers”), and induction of changes in behaviour of their own population or the other “partners”.
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