Rapid indicators for monitoring the health of Chlamydomonas nivalis biomass during preservation

E Bemejo-Padilla,B Taidi,R Filali,H Kinsou,B Perez-Bibbins

doi:10.1007/s10811-021-02517-w

Abstract

Microalgae are photosynthetic microorganisms that have increasingly attracted interest in the last decade due to their potential for industrial applications. One crucial aspect for the industrial-scale valorisation of algae biomass concerns the quality control during its preservation before being treated to obtain the end-product. Monitoring biomass quality is essential and can be potentially accomplished with the aid of specific biochemical indicators called biomarkers. In this context, the main aim of this work was to identify potential indicators of microalgae biomass viability that could be used as markers of its quality during storage/preservation for commercial operations. The health status of a suspension of Chlamydomonas nivalis was assessed at 4 ºC and 25 ºC during 10 days of storage. The use of the pulse-amplitude-modulation technique, based on chlorophyll fluorescence, was a valuable indicator of the culture viability. The measurement of DNA and of chlorophyll in the supernatant, indicative of cell lysis, also provided satisfactory results; in the case of the DNA, the limit of detection was 3.9 µg DNA·mL−1. The effect of different concentrations of a well-known and cheap preservative, acetic acid, was also evaluated at 4 ºC. This work identified three suitable biomarkers to be used as rapid indicators of the quality of the microalgal suspension prior to its reception for biorefinery activities.

Highlights

There is increasing interest in microalgae production due to their capacity to convert carbon dioxide into algal biomass and high-value biomolecules while producing oxygen viaThis research work was carried out while Elisabeth Bermejo was working at LGPM, CentraleSupélec, SFR Condorcet FR CNRS 3417, Centre Européen de Biotechnologie Et de Bioéconomie (CEBB), Université Paris-Saclay, 3 rue de Rouges Terres, 51110 Pomacle, FranceBiomass and target product quality control during microalgae preservation/storage represents a big challenge
A first study was performed to assess the correlation between chlorophyll fluorescence and chlorophyll concentration in C. nivalis cultures since this molecule has been described to present a positive relation with the photosynthetic activity (Chen et al 2011)
A real-time monitoring system is desired for the quality control of microalgae biomass and physiological status under storage conditions

Summary

Introduction

There is increasing interest in microalgae production due to their capacity to convert carbon dioxide into algal biomass and high-value biomolecules while producing oxygen viaThis research work was carried out while Elisabeth Bermejo was working at LGPM, CentraleSupélec, SFR Condorcet FR CNRS 3417, Centre Européen de Biotechnologie Et de Bioéconomie (CEBB), Université Paris-Saclay, 3 rue de Rouges Terres, 51110 Pomacle, FranceBiomass and target product quality control during microalgae preservation/storage represents a big challenge. The presence of DNA, by process degradation into oligonucleosomal fragments, can be used as an indicator of cell death in some species of microalgae (Segovia et al 2003; Zuppini et al 2007; Yordanova et al 2013) Chlorophyll is another molecule that can be used to evaluate the status of a microalgae culture. This pigment, which is an effective indicator of the physiological state of the photosynthetic apparatus, can be deactivated and degraded by changes in temperature and pH since it is very sensitive to these factors (Venkateswaran et al 2003; Koca et al 2005). During the preservation of microalgae biomass in the absence of light, this parameter can be a good indicator of PSII status and the potential damage caused by the preservation conditions (e.g. temperature, pH, dissolved oxygen concentration) and/or excess bacterial contamination

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