The Study of Caffeine as Novel Quorum Sensing Inhibitor

Abstract

Quorum sensing enables bacterial to communicate and at the same time control the gene expression in response to the cell density [1]. It is widely used by both gram-positive and gram-negative bacteria to regulate variety of bacterial physiological functions such as biofilm formation [2], bioluminescence [3], virulence factors [4] and swarming [5] which has been shown contribute to bacterial pathogenesis. With this knowledge, the use of QS inhibitor would be a particular value in treating bacterial pathogenicity and infections. In this work we have tested caffeine as quorum sensing inhibitor by using C.violaceum CV026 as a bioassay. This C.violaceum CV026 mutant strain is incapable of producing the purple pigment called violacein unless there are exogenous supply of N-hexanoylhomoserine lactone (C6-HSL) or other short chain AHL .The Inhibitory activity was measured by quantifying violacein production using a spectrophotometer. The results have revealed that Caffeine significantly reduced violacein production in a concentration dependent manner, indicating inhibition of quorum sensing. The presence of caffeine that exhibit anti-quorum sensing activity may be useful as the lead of anti-infective drugs.