Publication
Organic heterotrophic medium for Chlorella vulgaris: formulation and validation
| Summary: | The industrial production of microalgae is a practice under development and has become very promising, having various applications, such as the food industry, cosmetics, biofuels and wastewater treatment. Microalgae are preferably photosynthetic organisms. However, there are some with the capacity of growing using of organic carbon sources, i.e. hetero and mixotrophically. The most commonly used carbon source is glucose, due to its simplicity and energy potential. The objective of this thesis was to formulate an heterotrophic medium for Chlorella vulgaris, suitable for organic certification in accordance with European legislation. In relation to the biomass produced from this medium, it should meet Allmicroalgae requirements. Initially, ammonia concentrations in the MNBIO growth medium was optimized. Yeast extract was also tested, however, cultures achieved growth values below those obtained with MNBIO medium. As carbon sources, a hydrolyzed sugar with organic certification, together with a sterilization by filtration or sterilization by autoclavating were tested. The organic sugar sterilized by filtration was selected once, there were no statistically significant differences between C. vulgaris growth. Potassium bicarbonate was selected against calcium bicarbonate and sodium bicarbonate as a buffer to use during fermentation process. With this optimized heterotrophic medium, it was possible to obtain an organic medium suitable for the C. vulgaris growth, taking into account the European legislation. The optimized medium was tested in a 7 L bench-top fermenter, achieving dry weights of 39.2 ± 7.3 g L-1. These fermentations had productivities and global growth rate of 15.5 ± 1.4 g L - 1 d -1 and 1.68 ± 0.23 d-1, respectively. In relation to biochemical analysis, the protein and chlorophyll content obtained were 22.9 ± 11.8 % and 9.76 ± 1.90 mg g-1 DW, respectively. Comparing the results obtained with the inorganic production of Allmicroalgae for C. vulgaris, in terms of productivity and protein content are lower for the organic medium studied, but higher in the chlorophylls content. |
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| Main Authors: | Pereira, Francisco José Gonçalves de Veras |
| Subject: | Chlorella vulgaris Heterotrophy Industrial cultivation Organic Certification EU Heterotrofia Cultivo industrial Certificação Biológica UE |
| Year: | 2019 |
| Country: | Portugal |
| Document type: | master thesis |
| Access type: | open access |
| Associated institution: | Universidade do Minho |
| Language: | English |
| Origin: | RepositóriUM - Universidade do Minho |
| Summary: | The industrial production of microalgae is a practice under development and has become very promising, having various applications, such as the food industry, cosmetics, biofuels and wastewater treatment. Microalgae are preferably photosynthetic organisms. However, there are some with the capacity of growing using of organic carbon sources, i.e. hetero and mixotrophically. The most commonly used carbon source is glucose, due to its simplicity and energy potential. The objective of this thesis was to formulate an heterotrophic medium for Chlorella vulgaris, suitable for organic certification in accordance with European legislation. In relation to the biomass produced from this medium, it should meet Allmicroalgae requirements. Initially, ammonia concentrations in the MNBIO growth medium was optimized. Yeast extract was also tested, however, cultures achieved growth values below those obtained with MNBIO medium. As carbon sources, a hydrolyzed sugar with organic certification, together with a sterilization by filtration or sterilization by autoclavating were tested. The organic sugar sterilized by filtration was selected once, there were no statistically significant differences between C. vulgaris growth. Potassium bicarbonate was selected against calcium bicarbonate and sodium bicarbonate as a buffer to use during fermentation process. With this optimized heterotrophic medium, it was possible to obtain an organic medium suitable for the C. vulgaris growth, taking into account the European legislation. The optimized medium was tested in a 7 L bench-top fermenter, achieving dry weights of 39.2 ± 7.3 g L-1. These fermentations had productivities and global growth rate of 15.5 ± 1.4 g L - 1 d -1 and 1.68 ± 0.23 d-1, respectively. In relation to biochemical analysis, the protein and chlorophyll content obtained were 22.9 ± 11.8 % and 9.76 ± 1.90 mg g-1 DW, respectively. Comparing the results obtained with the inorganic production of Allmicroalgae for C. vulgaris, in terms of productivity and protein content are lower for the organic medium studied, but higher in the chlorophylls content. |
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