Applied Microbiology

Quorum sensing

Quorum sensing is the regulation of gene expression in response to fluctuations in cell-population density. Quorum sensing bacteria produce and release chemical signal molecules called autoinducers that increase in concentration as a function of cell density. The term Single Cell Protein (SCP) refers to the dried microbial cells or total protein extracted from pure microbial cell culture (Algae, bacteria, filamentous fungi, yeasts), which can be used as a food supplement to humans (Food Grade) or animals (Feed grade). Probiotics may seem new to the food and supplement industry, but they have been with us from our first breath. Probiotics serve as a source of functional and medical food.

Scope and Importance: The discovery that bacteria are able to communicate with each other changed our general perception of many single, simple organisms inhabiting our world. Instead of language, bacteria use signalling molecules which are released into the environment. As well as releasing the signalling molecules, bacteria are also able to measure the number (concentration) of the molecules within a population. Nowadays we use the term 'Quorum Sensing' (QS) to describe the phenomenon whereby the accumulation of signalling molecules enable a single cell to sense the number of bacteria (cell density). In the natural environment, there are many different bacteria living together which use various classes of signalling molecules. As they employ different languages they cannot necessarily talk to all other bacteria. Today, several quorum sensing systems are intensively studied in various organisms such as marine bacteria and several pathogenic bacteria.