Browsing by Autor "Luc Chauchat"

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Modulation of Membrane and Reserve Fatty Acids of the Thraustochytrid Aurantiochytrium mangrovei by Light and Temperature Culture Conditions
(Wiley, 2025) Mariana Ventura; Natalia Llopis Monferrer; Marc Long; Luc Chauchat; Nelly Le Goïc; Fabienne Le Grand; Philippe Soudant
This study aimed to investigate the effects of temperature, illumination, and growth stage on the cell morphology, lipid content, and fatty acid (FA) composition in neutral lipids (NL) and polar lipids (PL) of Aurantiochytrium mangrovei, a thraustochytrid, widely known for its capacity to accumulate docosahexaenoic acid (22:6n-3, DHA). Experiments were conducted at three different temperatures (15°C, 20°C, and 25°C) under both illuminated and non-illuminated conditions. Illumination of the culture significantly increased OCFA (15:0 + 17:0) in PL by 42%, 6%, and 11% at 15°C, 20°C, and 25°C. Proportions of 15:0 + 17:0 in NL and PL increased with increasing temperature, being highest at 20°C in the exponential phase (7% in PL and 9% in NL) and at 25°C in the stationary phase (15% in PL and 32% in NL). The temperature also increased the DPAn-6 proportion during the exponential phase, from 2.5% to 5.9% in NL and from 5.5% to 11% in PL, whereas DHA (22:6n-3) tended to decrease. The resulting DHA/Docosapentaenoic acid (22:5n-6, DPAn-6) ratio in both NL and PL was highest in cultures at 15°C during the exponential phase. Cultivation of A. mangrovei at 15°C was favorable to a high DHA proportion (61% of total FA in PL and 68% in NL) and a high DHA/DPAn-6 (> 11 in PL and 23 in NL) ratio during the exponential phase. Further research is needed to better understand why DHA and DPAn-6, two very long-chain PUFA, are regulated in an opposite manner in response to changing temperature.
Scale-Up to Pilot of a Non-Axenic Culture of Thraustochytrids Using Digestate from Methanization as Nitrogen Source
(Multidisciplinary Digital Publishing Institute, 2022) Denis de la Broise; Mariana Ventura; Luc Chauchat; Maurean Guerreiro; Teo Michez; Thibaud Vinet; Nicolas Gautron; Fabienne Le Grand; Antoine Bideau; Nelly Le Goïc
The production of non-fish based docosahexaenoic acid (DHA) for feed and food has become a critical need in our global context of over-fishing. The industrial-scale production of DHA-rich Thraustochytrids could be an alternative, if costs turned out to be competitive. In order to reduce production costs, this study addresses the feasibility of the non-axenic (non-sterile) cultivation of Aurantiochytrium mangrovei on industrial substrates (as nitrogen and mineral sources and glucose syrup as carbon and energy sources), and its scale-up from laboratory (250 mL) to 500 L cultures. Pilot-scale reactors were airlift cylinders. Batch and fed-batch cultures were tested. Cultures over 38 to 62 h achieved a dry cell weight productivity of 3.3 to 5.5 g.L-1.day-1, and a substrate to biomass yield of up to 0.3. DHA productivity ranged from 10 to 0.18 mg.L-1.day-1. Biomass productivity appears linearly related to oxygen transfer rate. Bacterial contamination of cultures was low enough to avoid impacts on fatty acid composition of the biomass. A specific work on microbial risks assessment (in supplementary files) showed that the biomass can be securely used as feed. However, to date, there is a law void in EU legislation regarding the recycling of nitrogen from digestate from animal waste for microalgae biomass and its usage in animal feed. Overall, the proposed process appears similar to the industrial yeast production process (non-axenic heterotrophic process, dissolved oxygen supply limiting growth, similar cell size). Such similarity could help in further industrial developments.