Microalgae culture quality indicators: a review

Abstract

Microalgae are photosynthetic microorganisms that have generated increasing interest in recent years due to their potential applications. Their biological capacity to grow faster than higher plants and their ability to convert solar energy into biomass and other bioactive molecules, has led to the development of various culture systems in order to produce different high-value products with commercial interest. The industrialization of the microalgae cultivation process requires the introduction of standardized quality parameters. In order to obtain bioactive compounds with high added value at a commercial level, it is necessary to sustainably produce biomass at a large scale. Such a process would imply specific stress conditions, such as variation in temperature, light or pH. These environmental conditions would make it more difficult to maintain the viability of the culture and protect the yield and condition of the target molecules. The physiological and biochemical impact of these stress factors on the microalgae biomass can be potentially measured by the presence and activity of various biochemical indicators called biomarkers. This review presents an overview of the main techniques that exist for assessing the "quality" of microalgae cultures through quantification of cell viability and vitality by monitoring specific markers indicative of the status of the culture.

Modeling and Optimizing the Effect of Light Color, Sodium Chloride and Glucose Concentration on Biomass Production and the Quality of Arthrospira platensis Using Response Surface Methodology (RSM)

“…The results of this study are in agreement with other studies [ 64 , 65 , 79 , 80 ]. Under stress, microalgae undergo significant metabolic and physiological changes, yielding an increase of cellular lipids, carbohydrates, carotenoids, and antioxidant enzymes [ 81 ]. Crucial alterations occur in the Spirulina proteome under salinity stress, yielding a reduction in the cellular protein content [ 82 ].…”

Strain Development in Microalgal Biotechnology—Random Mutagenesis Techniques

“…For this purpose, cell-impermeant dyes are commonly used. They are unable to cross intact membranes and can, therefore, be used for the analysis of cell viability and membrane integrity, allowing the estimation of the percentage of dead and vital cells [ 28 , 29 ]. Several dyes, such as SYTOX Green [ 30 , 31 ], propidium iodide [ 32 ], methylene blue, trypan blue, eosin and nile blue [ 29 ], have been applied so far.…”

“…They are unable to cross intact membranes and can, therefore, be used for the analysis of cell viability and membrane integrity, allowing the estimation of the percentage of dead and vital cells [ 28 , 29 ]. Several dyes, such as SYTOX Green [ 30 , 31 ], propidium iodide [ 32 ], methylene blue, trypan blue, eosin and nile blue [ 29 ], have been applied so far. Most studies aim for a survival rate of 5–20% to reach a good mutation rate within the surviving cell population [ 33 , 34 , 35 ].…”

Membrane inlet—ion mobility spectrometry with automatic spectra evaluation as online monitoring tool for the process control of microalgae cultivation

“…It is therefore important to closely monitor the culture to prevent losses. Consequently, such biotechnological processes require extensive process monitoring and control [ 12 ]. Most of the analytical techniques used for this purpose are off‐line procedures that require sample collection, sample preparation, or dilution of sample.…”

“…It is also used as a colorant in the food industry. Therefore, the commercial production of L. platensis growths throughout the world and an available analytical monitoring system would also have a high practical relevance here [ 12 ].…”