Rapid eco-toxicity analysis of hazardous and noxious substances (HNS) using morphological change detection in Dunaliella tertiolecta

Eco-toxicity testing assesses the potential harmfulness of unknown toxic substances as well as other effects of those substances, such as synergistic, additive, and antagonistic effects using various organisms including water flea, fish, benthic amphipod, and microalgae. Microalgae are important components in the food chains of marine ecosystems. Conventionally, the growth rate of an individual microalgae population is analyzed for 72 h to identify the effects of external stresses, e.g., chemicals, pH, temperature, CO2, etc. However, this method requires counting the number of microalgae every 24 h using a microscope, which is not only labor intensive but also requires substantial expertise. Dunaliella tertiolecta which rapidly changes its morphology when exposed to toxic substances, has been a species of interest among biomass and eco-toxicology researchers. However, such small changes are difficult to visualize and interpret with conventional microscopy or physicochemical techniques. Therefore, we propose a new method which utilizes microalgal morphological changes via lens-free shadow imaging technology (LSIT). To this end, a field-portable cell analyzer, NaviCell, which integrates LSIT was developed. Within this platform, the morphological changes of hundreds of microalgae can be automatically analyzed in parallel within just 3-4 min with over 96% precision and accuracy enabling rapid eco-toxicity evaluation.