MAPAPAIMA · Measure of Alkaline Phosphatase Activity of Plankton: An Integrated Microfluidic Approach

Measure of Alkaline Phosphatase Activity of Plankton: An Integrated Microfluidic Approach

Phytoplankton are microscopic organisms located at the base of the trophic web. These autotrophic cells play a major role in the biological production of the Oceans and are also responsible of roughly 40 % of the inorganic carbon fixation on the Earth, underlying their significant role in climate control. In the last decades, evidences of climate changes accompanying increase of Ocean stratification suggest that a decrease in mixing rates of deep nutrient-rich layers with surface nutrient-depleted waters. This increase of stratification leads to the decrease in nutrient availability for phytoplankton and a nutrient limitation in some areas. As a consequence an extension of areas with low phytoplankton concentration will arise in the future and lead to a drastic modification of the carbon cycle on the Earth. In the framework of an increase of Ocean stratification, the phosphate is an interesting candidate for controlling growth of organisms both in open and coastal oceanic regions. One of the main reasons of its potential limitation of phytoplankton growth is its very low concentrations usually measured in the upper layers in spite of its high turn-over rates. Phosphate acquisition is particularly complex both in open ocean and coastal environments because phytoplankton can also use organic phosphorus matters to survive to low phosphate concentrations. The main strategy to acquire dissolved organic phosphorus is to use a set of enzymes, such as Alkaline Phosphatase. A high rate of alkaline phosphatase activity (APA) is often detected in natural samples, especially in the dissolved fraction of the sample (<0.2µm). Although the dissolved fraction can represent the entire APA of a sample, nothing is known about the species responsible for this activity, the nature, and the fate of the high APA measured in the dissolved fraction. To better understand the role of this enzyme in phosphorus uptake and survival rate of the cell, the development of a new method capable to efficiently link the measurement of APA to a phytoplankton species in natural sample is essential. Why is it important for society? By their volumes and their places on Earth, the oceans are particularly important. Indeed, they act directly on the climate, by regulating surface temperatures, provide basic resources and ecosystem services to hundreds of millions of people and play a key role in the food security of many countries (FAO 2016). The main conclusions of the climate report published by the IPCC panel experts indicated that over a period of 40 years, the oceans are overall less salty, more acidic and warmer. This dynamic does not seem to be changing and the high temperature increasing stratification of the oceans also seems to induce increasingly severe limitations in nutrients. These profoundly and durably modify communities of species and the structure of ecological niches. Therefore, to better understand the future of the oceans and carbon fixation on the Earth, it is critical to investigate how the phytoplankton can develop adaptation to survive to nutrient limiting condition. In this project, 4 different objectives are required to successfully measure the APA at the single cell level using microfluidic technology. 1) Optimize the encapsulation of plankton species in a microfluidic chip. 2) Screen droplet containing a targeted plankton species. 3) Control the incubation and 4) Perform an alkaline phosphatase assay at a single cell level.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз