Fluorescence coupled with chemometrics for simultaneous monitoring of cell concentration, cell viability and medium nitrate during production of carotenoid-rich Dunaliella salina

Sá, Marta; Monte, Joana; Brazinha, Carla; Galinha, Cláudia F.; Crespo, João G.

doi:10.1016/j.algal.2019.101720

Cited by 13 publications

(14 citation statements)

References 30 publications

(44 reference statements)

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“…Fluorescence spectroscopy has recently been studied to monitor cell concentration in other microalgae, such as Dunaliella salina and Nannochloropsis oceanica (Sá et al, 2017, 2019a, 2020a). Nevertheless, according to the authors knowledge, it is the first time that this technique is used to develop one prediction model able to be used in different microalgae species, revealing the high potential of this technique to be used in microalgae production.…”

Section: Resultsmentioning

confidence: 99%

Production and monitoring of biomass and fucoxanthin with brown microalgae under outdoor conditions

Gao

Sá

Itd

et al. 2020

Biotech & Bioengineering

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The effect of light on biomass and fucoxanthin (Fx) productivities was studied in two microalgae, Tisochrysis lutea and Phaeodactylum tricornutum. High and low biomass concentrations (1.1 and 0.4 g L−1) were tested in outdoor pilot‐scale flat‐panel photobioreactors at semi‐continuous cultivation mode. Fluorescence spectroscopy coupled with chemometric modeling was used to develop prediction models for Fx content and for biomass concentration to be applied for both microalgae species. Prediction models showed high R2 for cell concentration (.93) and Fx content (.77). Biomass productivity was lower for high biomass concentration than low biomass concentration, for both microalgae (1.1 g L−1: 75.66 and 98.14 mg L−1 d−1, for T. lutea and P. tricornutum, respectively; 0.4 g L−1: 129.9 and 158.47 mg L−1 d−1, T. lutea and P. tricornutum). The same trend was observed in Fx productivity (1.1 g L−1: 1.14 and 1.41 mg L−1 d−1, T. lutea and P. tricornutum; 0.4 g L−1: 2.09 and 1.73 mg L−1 d−1, T. lutea and P. tricornutum). These results show that biomass and Fx productivities can be set by controlling biomass concentration under outdoor conditions and can be predicted using fluorescence spectroscopy. This monitoring tool opens new possibilities for online process control and optimization.

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Section: Resultsmentioning

confidence: 99%

Production and monitoring of biomass and fucoxanthin with brown microalgae under outdoor conditions

Gao

Sá

Itd

et al. 2020

Biotech & Bioengineering

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“…This variability in the cells originates fluorescence EEMs with different characteristics. Changes in the media composition, such as nitrate concentration, were also reported in other microalgae cultivations to originate a different fluorescence profile [32]. Also, the variability of EPA content that can be found in the two fractions of the cell, apolar (TAG) and polar (PL), increases the complexity of monitoring such product.…”

Section: Epa Monitoringmentioning

confidence: 88%

Monitoring of eicosapentaenoic acid (EPA) production in the microalgae Nannochloropsis oceanica

et al. 2020

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With the increase awareness for a healthier food regime and greener environmental processes, microalgae are being looked as a solution for a sustainable production of polyunsaturated fatty acids, such as omega-3 eicosapentaenoic acid (EPA). Nannochloropsis oceanica is an oleaginous microalga, well-known for the ability of EPA accumulation, although higher lipid productivities are still required to make the process competitive. Therefore, three cultivation parameters were tested in the present work (temperature, light cycles and nitrogen supply) in order to study the EPA profile in the polar and neutral fractions of the cells. In addition, an online monitoring tool based on a fluorescence spectroscopy technique was developed with the aim of increasing process knowledge at real time. The results of this work show that nitrogen depletion induces the highest variability in EPA accumulation in the neutral fraction (triacylglycerols). However, to increase the EPA content in the polar fraction a different strategy needs to be implemented, such as decreasing the cultivation temperature or the light available per cell. Chemometric models were developed through PCA (Principal Component Analysis) and PLS (Projection to Latent Structures), using only fluorescence spectra as inputs, enabling the monitoring of EPA in both fractions separately. High explained variance was observed (above 85%) in both fractions, with R 2 above 0.81 and slopes above 0.93 for both validation and training data sets. Lower values of cross-validation and prediction errors were observed (between 0.29 and 0.49% g/g DW ). The results obtained show that fluorescence spectroscopy is a powerful technique for online monitoring of non-fluorophore molecules, such as EPA, in complex process like microalgae cultivation.

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“…Fluorescence EEMs were measured in samples drawn from a cultivation of Dunaliella salina by Sa et al [41]. Samples were measured by an immersed optical fiber probe without any sample treatment, excitation 250-690 nm, emission 260-700 nm.…”

Section: Methods Based On Fluorescence Measurementmentioning

confidence: 99%

“…(1) [33] (2) [34] Chlorophyll fluorometry (1) [35] (2) [36][37][38] (2) (a) [39] (2) (b) [40,41] PAM fluorometry…”

Section: Cell Morphology Lipidsmentioning

confidence: 99%

On-Line Monitoring of Biological Parameters in Microalgal Bioprocesses Using Optical Methods

et al. 2022

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Microalgae are promising sources of fuels and other chemicals. To operate microalgal cultivations efficiently, process control based on monitoring of process variables is needed. On-line sensing has important advantages over off-line and other analytical and sensing methods in minimizing the measurement delay. Consequently, on-line, in-situ sensors are preferred. In this respect, optical sensors occupy a central position since they are versatile and readily implemented in an on-line format. In biotechnological processes, measurements are performed in three phases (gaseous, liquid and solid (biomass)), and monitored process variables can be classified as physical, chemical and biological. On-line sensing technologies that rely on standard industrial sensors employed in chemical processes are already well-established for monitoring the physical and chemical environment of an algal cultivation. In contrast, on-line sensors for the process variables of the biological phase, whether biomass, intracellular or extracellular products, or the physiological state of living cells, are at an earlier developmental stage and are the focus of this review. On-line monitoring of biological process variables is much more difficult and sometimes impossible and must rely on indirect measurement and extensive data processing. In contrast to other recent reviews, this review concentrates on current methods and technologies for monitoring of biological parameters in microalgal cultivations that are suitable for the on-line and in-situ implementation. These parameters include cell concentration, chlorophyll content, irradiance, and lipid and pigment concentration and are measured using NMR, IR spectrophotometry, dielectric scattering, and multispectral methods. An important part of the review is the computer-aided monitoring of microalgal cultivations in the form of software sensors, the use of multi-parameter measurements in mathematical process models, fuzzy logic and artificial neural networks. In the future, software sensors will play an increasing role in the real-time estimation of biological variables because of their flexibility and extendibility.

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Fluorescence coupled with chemometrics for simultaneous monitoring of cell concentration, cell viability and medium nitrate during production of carotenoid-rich Dunaliella salina

Cited by 13 publications

References 30 publications

Production and monitoring of biomass and fucoxanthin with brown microalgae under outdoor conditions

Production and monitoring of biomass and fucoxanthin with brown microalgae under outdoor conditions

Monitoring of eicosapentaenoic acid (EPA) production in the microalgae Nannochloropsis oceanica

On-Line Monitoring of Biological Parameters in Microalgal Bioprocesses Using Optical Methods

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