Ciencias Exactas y Ciencias de la Salud
Permanent URI for this collectionhttps://hdl.handle.net/11285/551014
Pertenecen a esta colección Tesis y Trabajos de grado de los Doctorados correspondientes a las Escuelas de Ingeniería y Ciencias así como a Medicina y Ciencias de la Salud.
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- Microalgae-based bioremediation of food and beverage processing wastewater: A sustainable approach toward a circular economy concept(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2025-12-03) Najar Almanzor, César Eduardo; Carrillo Nieves, Danay; mtyahinojosa, emipsanchez; Luzardo Ocampo, Iván Andres; Gutiérrez Uribe, Janet Alejandra; Chairez Oria, Jorge Isaac; Detrell, Gisela; Santaeufemia Sánchez, Sergio; Escuela de Ingeniería y Ciencias; Campus Guadalajara; García Cayuela, TomásFood and beverage production generates large volumes of nutrient-rich wastewaters that pose severe environmental challenges when discharged untreated. Effluents such as nejayote (from tortilla production), tequila vinasses (from tequila distillation), and cheese whey (from cheese production) contain high organic loads and extreme pH values that contribute to eutrophication and ecosystem disruption. Developing sustainable technologies that mitigate pollution while enabling resource recovery is therefore essential for advancing circular and cleaner production. This thesis evaluates microalgae-based bioremediation as an alternative for the treatment and valorization of these agro-industrial effluents. The work encompasses algae adaptation, process scale-up, biomass characterization, and environmental assessment. A UV-mutagenesis and gradual acclimatization strategy enabled Chlorella vulgaris, Haematococcus pluvialis, and Anabaena variabilis to grow in undiluted wastewater, achieving pollutant reductions of 87–99.9% in nejayote, 31–81% in vinasses, and 35–56% in whey. Although substantial, these results indicate that microalgae are best suited as components of a hybrid treatment systems rather than standalone technology. The technology’s scalability was validated through the cultivation of H. pluvialis in 100-L raceway pond, which maintained high remediation performance and biomass productivity despite minor declines associated with evaporation. The biomass showed significant protein and ash content, supporting potential use as biofertilizer, feed ingredient, or nutraceutical ingredient. Biochemical and functional characterization of biomass grown in nejayote and tequila vinasses revealed reduced pigment and phenolic content due to cultivation stress. However, extracts retained cytokine-modulating activity in RAW 264.7 macrophages, indicating potential for use as nutraceutical ingredient, animal feed, or biofertilizers following safety validation. Life Cycle Assessment comparing a microalgae-based vinasse treatment with the conventional industrial process showed similar overall environmental burdens but substantial reductions in terrestrial ecotoxicity and human carcinogenic toxicity. It also highlighted the need for optimization in coagulant sourcing and energy integration. Overall, this work demonstrates that microalgae-based treatment of agro-industrial effluents is technically viable, environmentally promising, and aligned with a circular bioeconomy, while identifying key challenges that must be addressed to enable industrial implementation.
- Phycoremediation as a circular bioeconomy process: unlocking microalgal potential for biomolecule production and wastewater treatment(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2025-06-17) Lopez Pacheco, Itzel Yolotzin; Aguilar Jiménez, Oscar A.; emimmayorquin; Ingenieria y ciencias; Campus MonterreyWastewater treatment processes have evolved in recent years due to the complexity of this residue generated worldwide. In recent years, there has been an increasing focus on integrating phycoremediation systems as a possible option for treatment processes. This doctoral thesis seeks to integrate and highlight all the benefits and processes involved in an established phycoremediation system and show its potential to be considered as a circular bioeconomy process. This thesis aims to provide guidance on why these systems can be installed in various areas and what their potential benefits might be. From wastewater treatment to biomolecules production, from microbial control to the reuse of water treated by this system, this doctoral thesis seeks to integrate all these processes through the analysis of previous studies and experimental work. In this research, it was evaluating the conditions of availability of nutrients (nitrogen, phosphorus and sulfur) that allow the greatest accumulation of value biomolecules from three strains of microalgae (Chlamydomonas reinhardtii, Chlorella vulgaris, and Scenedesmus sp.), to establish the implications of macronutrient variation in the accumulation of biomolecules and to visualize their possible impact on wastewater treatment. Microalgae can be grown in wastewater, making this a circular process, obtaining a valuable by-product derived from the reuse of this waste. In this way, it was evaluated the growth of one of the microalgae strains in two types of wastewaters. Determining by this way, the possibility to use wastewater as culture medium without affecting the productivity of biomolecules of interest for their next bioconversion. Finally, an evaluation of the behavior of bacteria during wastewater treatment was carried out, to determine if phycoremediation process can reduce these microorganisms and thus reduce the chlorination process in common wastewater treatment. This research in this sense shows the potential of producing microalgae biomolecules using wastewater as a culture medium for their bioconversion into valuable products such as bioplastics and one of the most interesting benefits of using phycoremediation as a method of wastewater treatment: microbial control.
- Genetic and biochemical analysis of the microalgae desmodesmus abundans After 13 years under high-CO2 for flue gas mitigation in a two-stage continuous photobioreactor system(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2022-12-06) Mora Godínez, Shirley María; MORA GODINEZ, SHIRLEY MARIA; 827922; Pacheco Moscoa, Adriana; puemcuervo, emipsanchez; Rodríguez López, Carlos E.; Treviño Alvarado, Víctor; Rojas Jiméne, Keilor; Diaz de la Garza, Rocío I.; School of Engineering and Sciences; Campus Monterrey; Senés Guerrero, CarolinaMicroalgae present high potential for greenhouse gases mitigation and value-added biomass production. In this project, the main objective was to characterize genetic and biochemical changes of high CO2 (strain HCA, 50% v/v CO2/air) and low CO2 (strain LCA, atmospheric, 0.04% v/v CO2/air) acclimated strains of Desmodesmus abundans RSM to elucidate adaptation mechanisms to high CO2. Also, a two-stage continuous photobioreactor system for cement flue gas mitigation was designed and optimized; and microalgal biomass was characterized to optimize CO2 capture and propose high-value byproducts of the system. Additionally, strains potential for biological synthesis of silver nanoparticle was evaluated. These objectives were divided into five studies. In the first study, the genome of D. abundans RSM with an estimated size of 83.61 Mbp was generated. A total of 14 251 genes were predicted, and 58.68 % of these were annotated. Also, carbon fixation pathways were characterized in which ninety-six sequences codifying for twenty-two enzymes were found. Orthologous gene analysis showed 5 414 gene families conserved among D. abundans RSM, Scenedesmus sp. NREL 46B-D3 and species from the Selenastraceae family (M. neglectum and R. subcapitata). Genomic comparison between the strain maintained in our laboratory and the same strain deposited in UTEX Culture Collection of Algae resulted in 902 723 genetic variants which were mainly single nucleotide polymorphisms, and genomes presented 44.36 % of collinear genes. These results evidence genomic changes in microalgae as consequence of adaptation to laboratory conditions; but also conserved gene families between close species in the same taxonomic order (Sphaeropleales). In the second study, the genome of D. abundans after thirteen years of acclimation to high CO2 (strain HCA) was characterized and compared to the strain LCA. Also, both strains were grown under high CO2 acclimation strategy of six months and, growth and genetic variants were characterized. Assembled genome of strain HCA resulted in an estimated size of 81.20 Mbp, in which 10 535 genes were predicted. Evolution of the strain HCA was characterized by some differentially annotated GO terms to LCA, and in phylogenomic tree that located this strain in a different distance than strain LCA based on 514 single-copy orthologous gene families. Also, it was found only 15.65 % of collinearity between strain genomes and a low number of reads (35.70%) from strain HCA that mapped in LCA genome. Evaluation of high CO2 acclimation strategy for six months showed that strain LCA reached similar growth than strain HCA by the end of the experimental period. Microalgae adaptation to high CO2 involved higher accumulation of genetic variants (130 082) than under air (107 163), resulting in estimated mutation rates of 3.17x10-5 and 2.85x10-5 per base per generation, respectively. Strain HCA under air presented higher difficulties to adapt to this condition and accumulated 119 334 variants in air and 82 360 in CO2 with mutation rates of 3.56x10-5 and 2.25x10-5 per base per generation. High CO2 acclimation strategy of six months represents a simple and rapid way to generate higher CO2 tolerant strains. In the third study, strains LCA and HCA were grown in different N-concentrations under a continuous flow of high CO2. Growth, biomass composition and gene expression of N-transporters and biosynthesis of starch and triacylglycerol were characterized. Maximum cell concentration increased for strain HCA at higher N, but not for LCA. Also, only strain LCA showed an adaptation phase of 24 h for all conditions, and higher N intake rates were determined in HCA. Biomass productivities were not significant different among N concentrations and strains, ranging 0.097-0.134 g d.w. L-1 d-1. Similar biomass productivities evidence microalgae carbon allocation into different metabolites and therefore similar CO2 capture efficiencies. In both strains, under the lowest N (6 mg L-1) starch accumulated up to 12.7-14.52 % d.w., which in high N (50-250 mg L-1) was 5.1-7.1 % d.w. Contrary, protein decreased as N decreased in the medium from 43.3-54.8 % d.w to around 14 % d.w. While accumulation of neutral lipids occurred only in strain LCA for all N conditions. In conclusion, after thirteen years under low and high CO2 acclimation, strains present differential response to N concentration under high CO2. Growth and composition in strain LCA were affected by N and high CO2, while HCA only by N availability. This was also evident in gene regulation, where HCA presented a faster response to growth condition than LCA. A fourth study with strain HCA, evaluated the growth and nutrient utilization (CO2, NOx and SOx) of this strain under a model cement flue gas (MFG; 25% CO2, 700 ppm NO, and 100 ppm SO2) using a limited N and without S medium (BG11-0.2N-S) and complete medium (BG11) in an optimized two-stage continuous photobioreactor system (TSCB). Also, biomass composition (starch, protein, pigments and lipids) and productivities; as well as fatty acid profile were characterized. Microalga tolerated and used flue gas as nutrient source when using the TSCB system, and pH was successfully controlled through system stages by adding 150 mg L-1 d-1 of cement kiln dust (CKD). Biomass productivities was around 1.2 g L-1 d-1 for both culture medium. When using BG11-0.2N-S medium 26% lower protein than in complete BG11 were obtained, with productivities of 0.46 ± 0.05 and 0.63 ± 0.05 g L-1 d-1, respectively. Contrary, starch and lipid were higher in low N medium. Pigment concentrations were 1.3 to1.4-fold higher in complete medium. Fatty acid profile showed higher content of PUFA in free fatty acid fraction under limited N, and in di and mono- glycerides under repleted N condition. Biomass and metabolite productivities were improved by using the TSCB system compared to batch cultivation strategies. Target metabolite accumulation was induced by using different N concentrations, where limited N in the second stage allocate carbon into starch and lipids, while medium with extra N into protein and pigments. In the last study, the potential of D. abundans strain LCA and HCA was evaluated as a suitable platform for silver nanoparticle (AgNPs) synthesis. The effect of biological components, namely, cell pellet, supernatant, and both components, were compared to the culture collection strain Spirulina platensis at different pH values. All biological components of strain HCA at pH 11 showed potential for nanoparticle synthesis. AgNPs (14.9 ± 6.4 nm diameter) with the lowest charge (-32.7 ± 5.3 mV) were observed using the cell pellet and, preserving the supernatant, resulted in synthesis of AgNPs in all pH solutions. In contrast, no nanoparticles were observed with components of strain LCA, except for the cell pellet at pH 11 (127.8 ± 14.8 nm, -26.7 ± 2.4 mV). The reducing power in strain HCA might be attributed to functional groups from proteins, carbohydrates, and fatty acids; and, in the supernatant, to amino acids, monosaccharides, disaccharides, and polysaccharides. Finally, AgNPs of the three microalgae strains exhibited similar antimicrobial properties against E. coli in the agar diffusion test. It is suggested that the high CO2 atmosphere potentiates biological components in D. abundans strain HCA, which might benefit their use in nanotechnology and represent an exciting byproduct from CO2 mitigation systems.