Vibrio cholerae Biofilm: Mechanisms, Regulating Formation and Signals of External Environment, Factoring Its Production

Abstract

Currently it is a common knowledge that the ability of cholera agent to form biofilm increases the survival rate and persistence both in external environment and macroorganism. V. cholerae cells in associated state are better protected from the effect of a range of factors, more effectively consume nutrient substances and exchange genetic information. The process of biofilm formation by cholera vibrio is investigated in sufficient detail. However, taking into consideration the significant role of this structure in the life cycle of V. cholerae, researchers obtain new data and clarify earlier gathered information on the molecular mechanisms that lie at the bottom of this process, using advanced analytical methods. Herewith, close attention is paid to studies of regulatory mechanisms of biofilm formation, as well as external environment signals that trigger it. This review presents previously obtained data and new information on V cholerae regulatory network, controlling the process of biofilm formation, including transcriptional activators, repressors, alternative sigma-factors, regulatory RNA, and a range of signal molecules. The role of regulatory mechanisms in biofilm formation inside a macroorganism is also considered in the paper. Given are the data on external environment signals (availability of nutrient substances (carbohydrates), bile, non-organic substances; change in osmolarity of the media), stimulating/suppressing its formation. Taking into account the critical role of exopolysaccharide in mature biofilm formation, as well as significant role of signal molecules of Quorum Sensing system and 3'-5'-cyclic diguanylate monophosphate in the process, a particular attention is drawn to mechanisms of exopolysaccharide biosynthesis and effect of the mentioned molecules.