Exploring Copper Tolerance in an Aquatic Janthinobacterium species: An Examination of Biofilm Formation and Viability for Environmental Applications

Heavy metal pollution is a growing environmental concern that has been exacerbated by the advent of industrial processes and the use of metals such as copper in agricultural and domestic sectors. Bacteria have developed mechanisms to resist the threats posed by heavy metal exposure, and have been studied for their utility as bioremediation agents to reduce pollution in contaminated sites. Biofilms may provide a protective advantage to bacterial cells exposed to toxic compounds such as metals. Using copper as a pilot heavy metal and an aquatic Janthinobacterium sp. strain isolated in the Hudson Valley, this study sought to examine the effects that copper-induced stress may have on biofilm formation and cell viability. To explore these effects, hyper-biofilm producing strains were created through transposon mutagenesis and morphological and behavioral analyses were performed. Results indicate that the strains examined here are able to tolerate copper at concentrations that are much higher than environmental levels. Although copper did not stimulate biofilm formation, results suggest that biofilm cells were able to tolerate higher concentrations of copper than planktonic cells. This information provides insight into the dynamics of copper tolerance in a ubiquitous aquatic model organism that may be appropriate for applications in bioremediation. This work can inform future studies aimed at understanding the impact of heavy metal contamination on the health of aquatic microbes, and can be extended to an ecosystem-wide scale