Ciencias Exactas y Ciencias de la Salud
Permanent URI for this collectionhttps://hdl.handle.net/11285/551039
Pertenecen a esta colección Tesis y Trabajos de grado de las Maestrías correspondientes a las Escuelas de Ingeniería y Ciencias así como a Medicina y Ciencias de la Salud.
Browse
Search Results
- Effect of SOx from simulated flue gas on growth and gene expression of S-compounds in the microalgae Desmodesmus abundans(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2024-11-11) Hernández Barrientos, Bryan Zeth; Pacheco Moscoa, Adriana; emimmayorquin; Mora Godinez, Shirley María; School of Engineering and Sciences; Campus MonterreyDesmodesmus abundans high CO2 acclimated strain (HCA) is a microalga adapted for 13 years to high CO2 atmospheres. Previous studies have shown overexpression of genes associated with purines and folate biosynthesis under model flue gas (250 000 ppm CO2, 700 ppm NO, and 100 ppm SO2). Therefore, it is hypothesized that a high S concentration in the growth medium generates biomass with desirable concentrations of S-containing compounds reflected in the overexpression of key genes involved in the biosynthesis of purines and folate, and other associated pathways such as cysteine, methionine, and S metabolism. D. abundans was cultured with different S concentrations in Erlenmeyer flasks to ¾ log phase (4 d) under 25% v/v CO2/air (continuous flow at 0.05 vvm), 300 mL BG11 medium, 25 ± 2 °C, 100 rpm, and 85 µmol PAR-photons m-2 s-1 of continuous light). Three experimental conditions in triplicate, and duplicated biologically, were tested: i) low S (BG11-3/4S, 7 mg L-1 SO42-), ii) high S (BG11-S+SOx, 100 ppm SO2 continuous supply), and iii) control (BG11, 29.2 mg L-1 SO42-). Gene expression analysis of pathways of interest was done using RNA-Seq. Analysis of differential expression of genes (DEGs) compared S treatments to the control (|Log2FC > 1| padj < 0.05). DEGs were obtained using CDS information of D. abundans HCA and filtered genes were mapped against KEGG pathways. Also, free amino acids were analyzed using a Waters ACQUITY UPLC® System with a fluorescence detector. Neither culture was inhibited by the growth condition (no lag phase) and exponential growth was similar among cultures; however, final biomass production was highest in the control (0.8 ± 0.1 g L-1 d.w.), followed by the high S and low S conditions (0.6 ± 0.06 and 0.51 ± 0.06 g L-1 d.w. respectively). Therefore, the presence of SOx slightly reduced by 19% final biomass production. A similar trend was observed for total protein content with a greater reduction of 38% under high S (56.2 ± 1.6%, 34.6 ± 0.41%, and 26.5 ± 3.7% d.w. for the control, high S, and limited S, respectively). DEGs showed that S-limitation resulted in up-regulation of sulfate assimilation- related genes but did not correlate to a greater quantity of S-containing amino acids and only the serine O-acetyltransferase (SAT) gene was upregulated in the cysteine and methionine pathways under this condition. Although upregulation in the folate biosynthesis pathway could be observed in both conditions, these genes were not related to the interconversion of folate derivatives. Given that gene expression of reactions of interest was not clearly observed through transcriptomic analysis, neither synthesis of S-containing amino acids, implementation of direct approaches based on sequence homology of specific genes and quantification of other S related compounds as folate should be pursue.
- Culture of Euglena gracilis in photoautotrophy for paramylon production: effect of pH and media composition(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2021-11-15) Martín Roldán, María; ; Pacheco Moscoa, Adriana; puemcuervo/tolmquevedo; Senés Guerrero, Carolina; School of Engineering and Sciences; Campus Monterrey; Valledor González, LuisMicroalgae have been widely studied in biotechnology for their application in various areas such as bioremediation, production of biofuels, or use in nutrition. More specifically, certain species are recognized to produce compounds of high commercial value. Euglena is a group of microalgae characterized by the generation of the reserve polysaccharide paramylon, with promising prospects for its application in pharmacology, nutrition, to produce bioplastics, or biodiesel. Paramylon is accumulated mainly in the presence of organic carbon in the culture medium; however, this represents a challenge when establishing a large-scale culture due to the risk of biological contamination. In this study, an extensive study of the literature was carried out with respect to the autotrophic culture of Euglena gracilis destined to paramylon production. As a result, we evaluated the effect of culture pH, vitamin supplementation, and nitrogen source in the culture medium in order to reach the maximum biomass productivity. A pH of 7.5 and ammonium as nitrogen source were optimum for the autotrophic culture of E. gracilis, while an improvement in productivity was not observed with vitamin supplementation. Finally, it was possible to scale up the photoautotrophic culture of E. gracilis to a 1-L airlift photobioreactor. In conclusion, there is still much optimization work to achieve the biomass and paramylon productivity reported for the heterotrophic cultures of E. gracilis, but the results of this study reveal its viability.
