An Investigation of the Molecular Mechanism of Quorum Sensing in J. lividum

Abstract

Janthinobacterium lividum (J. lividum) is a rod shaped, Gram-­‐negative, motile, aquatic bacterium known to secrete violacein, a dark purple pigment with antibacterial, antitumor, antiparasitic, and antifungal characteristics (Durán and Menck 2001; Wille and Steglich 2001; Pantanella et al. 2006). Additionally, Harris et al. determined that violacein reduces and may potentially eliminate Batrachochytrium dendrobatidis (Bd) infection (Harris et al. 2009). Bd is an invasive chytrid known to cause chytridiomycosis; a disease that has affected over 200 species of amphibians, one third of which are now nearing extinction (Brucker et al. 2008; Harris et al. 2009). The genes that regulate the production of violacein in J. lividum are unknown, yet pigment production is predicted to be under the control of the suite of genes responsible for quorum sensing (Pantanella et al. 2006). Quorum sensing (QS) is density dependent gene expression in response to bacterial communication characterized by the exchange of small signaling molecules known as autoinducers. In this study, a random mini-­‐Tn5 transposon library of BJB1, an environmental isolate of J. lividum, was generated and screened for unique pigment phenotypes as a representation of QS phenotypes. This study identified six genes potentially involved in quorum sensing in BJB1. By elucidating the specific genes involved in QS, it may be possible to modify gene expression in J. lividum to enhance its pigment production, making it a more attractive therapeutic agent against Bd and other pathogens