Non-destructive monitoring tools for biomass and astaxanthin production in Haematococcus pluvialis rotating biofilms: a spectroscopy approach - Archive ouverte HAL
Communication Dans Un Congrès Année : 2023

Non-destructive monitoring tools for biomass and astaxanthin production in Haematococcus pluvialis rotating biofilms: a spectroscopy approach

Résumé

Biofilm-based systems have gained increasing attention for microalgae cultivation due to their potential to improve productivity, reduce water and energy demands and eventually operating costs. However, effective operation of these systems requires process control, which relies on the development of on-line monitoring of process variables such as biomass, pigments and lipids contents. While there are various methods and technologies for monitoring these biological parameters in microalgae suspensions, at present, there is a lack of tools for non-destructively monitoring biofilmbased systems. In this study, we developed a biofilm-based rotating system for cultivating Haematococcus pluvialis biofilms for astaxanthin production (high-value carotenoid). The dynamics of biomass and astaxanthin production were afterwards determined under several light and nutrient conditions. The data collected were then used to develop regression models based on Fourier-transform infrared (FTIR) and reflectance spectroscopy (Vis-NIR; 380-1000 nm) to non-destructively monitor biofilm growth and astaxanthin content. FTIR spectroscopy is an effective technique for high-throughput screening in biology as it can distinguish and quantify various components such as proteins, lipids, nucleic acids, and carbohydrates. In H. pluvialis, the biosynthesis of astaxanthin matches the accumulation of triacylglycerols (TAGs) leading to a complex macromolecular reorganization (Figure 1), suggesting that FTIR spectra could be used to quantify the astaxanthin content. Indeed, cell populations rich in astaxanthin could be easily identified by the ratio between macromolecules, and a linear regression between astaxanthin content and the lipids-to-proteins ratio was obtained (Figure 2). This method is non-invasive, does not require a chemical extraction step, and can be used to monitor and predict astaxanthin production in microalgal biofilm systems. However, the strong absorption of water between 1700 and 900 cm-1 may limit its application for real-time monitoring. To address this, we propose the use of reflectance spectroscopy, which stands on the light reflected at specific wavelengths to calculate indexes that are widely applied to remotely characterize plants and microphytobenthos communities. These indexes strongly reflect specific physiological mechanisms and biochemical composition, making them effective in estimating biomass, pigments, and identifying stress changes. To demonstrate this, we applied the same principle to our biofilmbased system and develop indexes for estimating biomass and astaxanthin content. Reflectance measurements were performed at the biofilm surface over time (Figure 3). The most influential wavelengths were afterwards determined for these variables as λ525, λ637, λ563, λ678 nm and near-infrared (NIR λ750-900 nm). A strong correlation between biomass and an index based on NIR and λ525 nm was found (R2 = 0.938); another was established between an index using λ563 and λ637 and astaxanthin content (R2= 0.944) (Figure 4). In summary, we developed, for the first time, non-destructive and in situ monitoring tools for microalgae biofilm characterization. Our findings address one of the limitations in process control, and have the potential to improve the operation of biofilm-based systems, making them a promising technology for microalgal cultivation and the production of high-value compounds
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Dates et versions

hal-04443825 , version 1 (07-02-2024)

Identifiants

  • HAL Id : hal-04443825 , version 1

Citer

David Morgado Pereira, Andrea Fanesi, Thierry Martin, Sihem Tebbani, Olivier Bernard, et al.. Non-destructive monitoring tools for biomass and astaxanthin production in Haematococcus pluvialis rotating biofilms: a spectroscopy approach. 14th European Congress of Chemical Engineering and 7th European Congress of Applied Biotechnology, Sep 2023, Berlin (DE), Germany. ⟨hal-04443825⟩

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