Search

Microalgae production systems have gained significant attention in recent years due to their potential to provide sustainable solutions for various challenges faced by society. Controlling the growth of target microalgal strains in large-scale production systems is challenging and is crucial for sustainable biomass production and a circular bioeconomy. These systems are composed of very diverse microbial communities, whose dynamics could largely explain the reasons why these systems generally operate well below their optimal yield. However, our understanding of these microbial community dynamics remains limited. This study focuses on characterizing the community dynamics of a Tetradesmus almeriensis culture in an open photobioreactor system fed with wastewater. The eukaryotic community was dominated by the microalgae T.almeriensis and species of Fungi. The composition of the fungal community changed as the concentration of microalgae increased, while the bacterial community was dominated by: Gammaproteobacteria, Actinobacteria, Bacteroidota, and Cyanobacteria. Our analysis suggests that these dynamics had both positive and negative implications for the industry. On the one hand, we observed fungal presence in the culture system. On the other hand, our study revealed the presence of highly diverse bacterial communities with high turnover rates at the ASVs level, which may stimulate the growth of microalgae. This knowledge is of potential significance for the industry, as it can contribute to improving the yields of large-scale microalgae production systems

[EN] Microalgae and microalgae-derived ingredients are one of the top trends in the food industry. However, consumers' acceptance and purchase intention of a product will be largely affected by odour and flavour. Surprisingly, the scientific literature present a very limited number of studies on the volatile composition of microalgae and cyanobacteria. In order to fill the gap, the main objective of the present study was to elucidate the volatile composition of seven microalgal and cyanobacterial strains from marine and freshwaters, with interest for the food industry while establishing its potential impact in odour. Among the seven selected strains, Arthrospira platensis showed the highest abundance and chemical diversity of volatile organic compounds (VOCs). Aldehydes, ketones, and alcohols were the families with the highest diversity of individual compounds, except in Arthrospira platensis and Scenedesmus almeriensis that showed a profile dominated by branched hydrocarbons. Marine strains presented a higher abundance of sulfur compounds than freshwater strains, while the ketones individual profile seemed to be more related to the taxonomical domain. The results of this study indicate that the VOCs composition is mainly driven by the individual strain although some volatile profile characteristics could be influenced by both environmental and taxonomical factors.

[Resumen] Las microalgas son organismos capaces de realizar la fotosíntesis, aprovechando la luz y el CO2 para crecer y aumentar su biomasa, la cual es muy valiosa en el desarrollo de multitud de aplicaciones. En la actualidad, la biomasa de microalgas está atrayendo el interés de nuevos sectores industriales, como los biocombustibles, los biopesticidas, la nutrición humana, los cosméticos y la acuicultura. Uno de los parámetros fundamentales para el crecimiento óptimo de las microalgas es un adecuado suministro de nutrientes. Las microalgas para crecer, aparte de luz, carbono y agua, necesitan el nitrógeno (N) y el fósforo (P), además de otros micronutrientes. En la producción de microalgas con agua limpia, estos macronutrientes se administran en forma de nitratos (NO-3) y fosfatos (PO4 3-), respectivamente. Sin embargo, este aporte de nutrientes representa un alto coste de la producción global. Por ello, es fundamental optimizar el aporte global de sales al cultivo, sin limitar el crecimiento de los microorganismos y reduciendo los costes. Bajo este enfoque, se realizó un estudio preliminar para desarrollar un sensor virtual para el seguimiento de nutrientes (NO- 3, PO4 3-) en un cultivo de microalgas utilizando para ello una sonda de conductividad eléctrica. Mediante la señal proporcionada por el sensor, ha sido posible determinar la concentración de sales en el cultivo a partir de las constantes de conductividad determinadas en laboratorio. La correlación obtenida se validó primero a escala de laboratorio y posteriormente en sistemas reales (reactor raceway, 80 m2) con una alta precisión (R2=0.8). Los resultados obtenidos son prometedores ya que pueden permitir alcanzar una buena aproximación para estimar la concentración de sales, como NO-3, y PO4 3-, en los cultivos de microalgas, utilizando la medida de conductividad., [Abstract] Microalgae are photosynthetic organisms that can grow under light and convert CO2 into valuable biomass. Nowadays, microalgae biomass is attracting the interest of new merging industrial sectors such as biofuels, biopesticides, human nutrition, cosmetics and aquaculture. One of the key parameters for optimal microalgae growing is adequate nutrient supply. Microalgae, apart from light, carbon, and water, need macronutrients such as nitrogen (N) and phosphorus (P) to grow. In microalgae production with clean water, these nutrients are supplied in the form nitrates (NO3-) and phosphates (PO4 3-), respectively. However, the nutrients are generally provided by fertilizers, representing a high cost of the overall production. For this reason, optimizing the overall salts' contribution to the culture is fundamental not limiting their groth and reducing costs. In this framework, it was developed an online sensor for the nutrients (NO3 -, PO4 3-) tracing in a microalgal culture using a conductivity probe. Using the signal provided by the sensor, it was possible to determine the concentration of salts in the culture from a mathematical correlation and by measuring theconductivity constants in the laboratory. The described correlation was determined first in small lab scales and then in real systems (Raceways reactor, 12 m3) with a high accuracy (R2=0.8). The results obtained are promising as they may allow to reach a good mathematical approximation to estimate the salts' concentration using the conductivity measure.