Assessing Ecotoxicity in Marine Environment Using Luminescent Microalgae: Where Are We At?

Abstract

Nowadays, microalgae are particularly used to assess the environmental impact of contaminants in aquatic systems. Naturally present in some algal species, bioluminescence is highly used in application fields related to environmental monitoring. Bioluminescent dinoflagellates have played a pivotal role in this domain. When exposed to heavy metals or toxic organic compounds, bioluminescent dinoflagellates have the capacity to decrease light emission. In addition, new molecular tools allow the possibility to produce genetically modified microorganisms which are able to perform luminescence. Combined with the luciferase reporter gene, two main genetic constructions can be employed. Activation of a specific inducible promoter induces the luminescence gene transcription and this signal increases over time. Constitutive promoters result in a high basal expression level of the reporter gene. During exposure to a potential toxic pollutant, the basal expression level will decrease due to the toxic effect. Toxicity bioassays based on engineered luminescent Chlorophyta microalgae are among the most sensitive tests and are an invaluable complement to classical toxicity assays.