Ocean biogeochemical perturbations by plasticizers

Microbes are the engines driving the global cycling of nutrients since they have the genes encoding for the main proteins/enzymes involved in the transformation of energy and matter in the ocean. Thus, microbial activities/functions are fundamental to how the ocean operates with implications ranging from fisheries to climate change. Plastics are made of a basic polymer and different additives, among them the plasticizers, which confer functional properties to the material. While pollution by plastics has been the subject of abundant scientific research efforts, the specific effects of plasticizers have received less attention. Plasticizers are found ubiquitously in the upper ocean, are bioavailable and directly interact with microorganisms the base of ocean food webs and drivers of ocean biogeochemical cycles. Yet, little is known about the ability of microbial populations to modulate the fate of plasticizers and the effects of those on microbial communities. This proposal addresses the fundamental, albeit unexplored problem of the effects of the plastic additives (plasticizers), on the oceanic microbial diversity, activity and ecosystem functioning. Three model families of plastic additives: organophosphate ester flame retardants and plasticizers, phthalic acid esters, and bisphenols, are selected as model key organic contaminants, as they have been widely used as plasticizers for the last decades. Although anthropogenic perturbations to the ocean have been recognized for some decades, the application of multi-omic approaches to specifically test the effect of plasticizers alone, or in combination with other climatic stressors is lagging behind. Hence, we will combine the use of multi-omics molecular tools and classic metabolic rate measurements to decipher the impact of key marine plasticizers on the phylogenetic and functional diversity of microbes as well as on their ecosystem functions. Collectively, the research proposed here will provide a mechanistic understanding on the ecology and biogeochemical cycles modulated by plasticizers in the present and future ocean. This is a highly relevant issue as plastics are widely used in modern societies and plasticizers have likely a bigger impact on microbes than the bulk polymeric constituents of plastics.