Survival of Microbial Bacteria Essay

1363 Words 6 Pages
Microbial world frequently face abrupt changes in the surrounding environment. For the survival in such a dynamic environment, it is advantageous to take decision of future action at the population level. Bacteria do so by a phenomenon called quorum sensing (QS), which is sensing the presence of other bacteria in surrounding environment, and taking the decision at certain threshold cell density. In QS active state, bacteria induces certain set of target genes at population level. QS among bacteria is mediated by autoinducers (AIs), whose concentration is a function of cell density, and above a certain concentration of cells AI mediate QS. There are three classes of AIs, (a) AI-1: Chemically these are acyl homoserine lactone (AHL). These …show more content…
AI molecules are frequently detected using QS biosensor strains. During last decade several biosensors have been developed to detect and quantify AI molecules. Most of the biosensors are designed to sense either AI-1 or AI-2. These biosensors are efficient in detecting presence of AI(s) in a bacteria, as well as in screening of QS inhibitors(Tello et al., 2013, Anbazhagan et al., 2012). A bacterial biosensor is a genetically recombinant bacterium, which harbors a QS genecircuit of interest coupled with an easily detectable and quantifiable reporter gene circuit. Reporter gene generates different classes of readable output including fluorescence, color pigments, and luminescence. QS molecules can also be screened using several analytical methods including HPLC and Mass Spectrometry(Rutherford and Bassler, 2012). But, in comparison to chemical based methods, biosensors are easy to use and inexpensive to construct and provide real time data in physiologically relevant environmental conditions. Most of quorum sensing biosensors express a reporter gene expressed from a QS responsive promoter. This promoter gets activated when a complex of AI and QS transcriptional activator bind with the promoter. Some biosensors respond to a very specific to a particular type of AI, and some respond to a

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