Accurate physiological monitoring using lab-on-a-chip platform for aquatic micro-organisms growth and optimized culture

Abstract

The present work was dedicated to the development of a lab-on-chip microsystem for the monitoring of microalgal photosynthetic activity. Thanks to integrated electrochemical microcells, dissolved oxygen O2 concentrations due to photosynthetic microalgal activity were measured in a continuous way and oxygen production rates of microalgae cultures were finally determined in the frame of artificial night/day cycles. Application was performed by studying the physiological metabolisms of the green microalga Chlamydomonas reinhardtii. First, the different growth dynamics of microalgal cultures were characterized, enabling the determination of the induction, "exponential growth", "declining growth rate" and stationary phases. Then, the influences of carbon-based nutrients, such as sodium bicarbonate HCO3Na and methanol CH3OH, as well as of pollutants, such as silver nitrate AgNO3, were studied, evidencing contradictory behaviors according to the competition between nutritional properties, toxicity effects and acclimation phenomena. This paves the way to the development of analysis microsystems for the understanding of microalgal metabolisms as well as for the improvement of microalgae growth processes and associated industrial production.

Activated Carbon Preparation from Sugarcane Leaf via a Low Temperature Hydrothermal Process for Aquaponic Treatment

“…It can be seen that the amount of DO in the water for all ponds increases with an increasing of the time of raising the fish. This is due to the presence of an induction phase for microorganism growth in water during which minimal increases in cell density occurs, or when the physiological adaptation of the cell metabolism to growth in the first week takes place [ 42 ]. In addition, this also resulted in the presence of more plant roots over the experimental time, which helps to add oxygen to the water.…”

Antioxidative Responses of Chlorella vulgaris Under Different Growth Phases

“…During this phase, the growth of microalgae reaches the maximum specific growth rate. However, the specific growth rate depends on species of algae, light intensity and temperature (Belaïdi et al, 2020). The declining growth phase occurs when the growth requirements for cell division are limited.…”

“…From day 10 to day 18, the growth of the cells started to enter the stationary phase, where the limiting factor and the growth rate were balanced, resulting in relatively constant cell density. The death phase begins after day 19 when the cell density rapidly decreases due to depletion of limiting factors such as nutrient deficiency, oxygen, overheating, pH alteration, and contamination (Lee et al, 2015;Belaïdi et al, 2020). In this study, cells were harvested on days 1, 6, 9, 14 and 20 to represent the five growth phases: lag, log, declining, stationary and death phases.…”

Microfluidic-Based Oxygen (O2) Sensors for On-Chip Monitoring of Cell, Tissue and Organ Metabolism

“…Passivation materials are also used to not only define the electrode surface but also ensure their long-term EC stability. In an attempt to develop a low-cost, easy-to-use, reproducible and portable microfluidic device, a specific B33 glass substrate was used [ 91 ]. The idea was to initiate and monitor microalgae photosynthesis activity while electrochemically assessing the microalgal O 2 production rate during artificial night/day cycles.…”