Effect of temperature and heavy metals on biofilm formation of Vibrio cholerae

Abstract

Vibrio cholerae, is a waterborne pathogen capable of persisting in aquatic environments through its ability to form biofilms, which allow survival, transmission, and increased resistance. Environmental temperature fluctuation and heavy metals play critical roles in influencing biofilm development. This review discusses current research showing that temperature and heavy metals are two of the most important abiotic factors influencing V. cholerae biofilm development, architecture, and importance to public health. Temperature is one of the key regulators that dictate the planktonic–biofilm transition. Generally low to moderate temperatures (15–25 °C) promote V. cholerae biofilm, and this correlates with an increase in intracellular c-di-GMP, activation of the regulatory network, activation of cold-adaptation pathways, and increased expression of adhesive proteins, e.g. MSHA pili and GbpA. These responses support V. cholerae attachment and survival in seawater during seasonal transitional periods. The exposure to heavy metals such as Cd, Cu, Pb, Zn, Ni, Hg, and As imposes oxidative stress, destabilization of the cellular membrane, and inhibition of multiple enzymes. Vibrio cholerae can manage its level of toxicity by regulating it through a collection of metal responsive regulators. In addition, toxic metal stress frequently selects for enhanced EPS production, thicker biofilms, and co-selection of metal tolerance, biofilm proficiency, and potentially antimicrobial resistance. The review suggests that temperature acts as a primary regulatory factor, while metal toxicity would function solely as a selective pressure for regulating biofilm architecture. The survival strategy of bacteria may interact synergistically in cholera endemic estuaries where there are both seasonal temperature increases, along with increased industrial discharge, VBNC transitions, and outbreak timing. Notable knowledge gaps include limited experiments on temperature and heavy metals affecting V. cholerae biofilm formation and persistence in aquatic ecosystems. Therefore, it needs to resolve molecular cross-talk between metal stress signalling, quorum sensing, and temperature-controlled c-di-GMP pathways. Integrating metal monitoring for cholera, WASH interventions, and the need for implementation of One Health frameworks as methods for reducing the persistence of the environmental reservoir and the potential for outbreaks.