Off-line and on-line optical monitoring of microalgal growth.

Hugo-Enrique Lazcano-Hernández,Gabriela Antonia Dzul-Cetz,Javier Arellano-Verdejo,Rodrigo Patiño,Gabriela Aguilar

doi:10.7717/peerj.7956

Abstract

The growth of Chlamydomonas reinhardtii microalgae cultures was successfully monitored, using classic off-line optical techniques (optical density and fluorescence) and on-line analysis of digital images. In this study, we found that the chlorophyll fluorescence ratio F685/F740 has a linear correlation with the logarithmic concentration of microalgae. By using digital images, the biomass concentration correlated with the luminosity of the images through an exponential equation and the length of penetration of a super luminescent blue beam (λ = 440 nm) through an inversely proportional function. The outcomes of this study are useful to monitor both research and industrial microalgae cultures.

Highlights

Photosynthesis is a biophotonic mechanism by which green plants, cyanobacteria and algae, transform a fraction of the solar energy, to produce their own food
It has been established in a previous work that the Gompertz model represents the C. reinhardtii growth better than the classical Monod model
Growth of C. reinhardtii cultures were successfully monitored throughout off-line and on-line optical techniques at affordable cost

Summary

Introduction

Photosynthesis is a biophotonic mechanism by which green plants, cyanobacteria and algae, transform a fraction of the solar energy, to produce their own food. This is the foundation of life on Earth. Photosynthesis occurs in the chloroplasts, which are those cell organelles that contain the photosynthetic pigments (chlorophyll a, chlorophyll b, carotenoids, etc.). They absorb light and use it to drive photosynthetic light reactions and associated electron transport reactions to reduce CO2 and oxidize H2 O in the Calvin cycle (Allen, 1992). The net result of photosynthesis is the production of carbohydrates and the release of molecular oxygen to the atmosphere. Environmental factors such as temperature, irradiance, humidity and salinity are known to affect photosynthesis (Rym, 2012)

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