Rosa Leonor González-Díaz

Brewer’s spent grain (BSG) is an abundant lignocellulosic by-product whose valorization can support circular bioeconomy strategies. This study evaluated BSG bioconversion by Aspergillus oryzae ATCC 10124 under solid-state fermentation (SSF) to produce lignocellulolytic enzymes and release second-generation (2G) sugars relevant to biorefinery applications. SSF was monitored over 0–10 days, and FPase, endo-cellulase, β-glucosidase, xylanase, mannanase, amylase, and ligninolytic enzyme activities were quantified. Enzymatic crude extracts were further assessed in SDS-PAGE analysis. Glucose, cellobiose, xylose and arabinose release and consumption were tracked throughout fermentation, and substrate transformation was supported by FTIR. The secretome exhibited a predominantly hydrolytic profile, with maximal hemicellulolytic and cellulolytic activity around days 2–4, as well as sustained amylase activity. Ligninolytic activity was not detected. Sugar profiles indicated rapid early hydrolysis of glucose, followed by progressive pentose release. The stabilization and decline were consistent with fungal uptake. Changes in the carbohydrate fingerprint and SDS–PAGE banding supported structural polysaccharide remodeling and hydrolytic protein secretion. Thus, this SSF platform confirmed certain potential for low-cost cellulolytic and hemicellulolytic enzyme generation. However, because sugar accumulation was temporary and followed by consumption, this system is best interpreted as a biological pretreatment and enzyme-generation step that supports subsequent downstream valorization.

Brewer’s spent grain (BSG), the main lignocellulosic by-product of the beer industry, represents an abundant yet underutilized resource with high potential for valorization. This study presents an integrated biorefinery approach to convert BSG into second-generation (2G) ethanol, bioactive vinasse for plant growth promotion, and fungal biomass as a potential mycoprotein source. The biomass was first subjected to biological delignification using the white-rot fungus Ganoderma lucidum, after which two valorization routes were explored: (i) evaluation of the fungal biomass as a mycoprotein candidate and (ii) alcoholic fermentation for ethanol production. For the latter, three pretreatment strategies were assessed (diluted sulfuric acid and two deep eutectic solvents (DESs) based on choline chloride combined with either glycerol or lactic acid) followed by a one-pot enzymatic saccharification and fermentation using Kluyveromyces marxianus SLP1. The highest ethanol yield on substrate (Y_P/S) was achieved with [Ch]Cl:lactic acid pretreatment (0.46 g/g, 89.32% of theoretical). Vinasse, recovered after distillation, was characterized for organic acid content and tested on Solanum lycopersicum seed germination, showing promising biostimulant activity. Overall, this work highlights the potential of BSG as a sustainable feedstock within circular economy models, enabling the production of multiple bio-based products from a single residue.

Microalgae offer a sustainable alternative for wastewater treatment by simultaneously removing pollutants and producing biomass of potential value. This study evaluated five species—Haematococcus pluvialis, Chlorella vulgaris, Chlamydomonas sp., Anabaena variabilis, and Scenedesmus sp.—in three undiluted food and beverage industry effluents from Mexico: nejayote (alkaline wastewater generated during corn nixtamalization for tortilla production), tequila vinasses (from tequila distillation), and cheese whey (from cheese making). Strains were adapted through UV mutagenesis and gradual acclimatization to grow without freshwater dilution. Bioremediation efficiency was assessed via reductions in chemical oxygen demand (COD), total nitrogen (TN), and total phosphates (TPO₄). C. vulgaris achieved complete TN and TPO₄ removal and 90.2% COD reduction in nejayote, while A. variabilis reached 81.7% COD and 79.3% TPO₄ removal in tequila vinasses. In cheese whey, C. vulgaris removed 55.5% COD, 53.0% TN, and 35.3% TPO₄. These results demonstrate the feasibility of microalgae-based systems for treating complex agro-industrial wastewaters, contributing to sustainable and circular wastewater management.

The Santiago-Guadalajara River, located in western Mexico, is one of the most polluted rivers in the country, with widespread fecal contamination that presents a potential risk to public health, food safety, and biodiversity. This study investigated the spatial and seasonal behavior of fecal indicator bacteria (FIB) in the Santiago-Guadalajara River Basin (SGRB) using the most probable number (MPN) microbiological quantification technique and measuring the tributary flow rates in the main stem of the river and tributaries. Twenty-five sampling sites were monitored from July 2021 to April 2022. The mean of the microbial counts (MPN/100 mL) at the basin was as follows: total coliforms 2.5 × 10⁷, fecal coliforms 2.2 × 10⁷, and E. coli 2.1 × 10⁷. These FIB values position the Santiago-Guadalajara River as one of the most polluted rivers globally since it significantly exceeds the regulatory limits at the monitored sites, indicating insufficient sanitation infrastructure throughout the basin. A high level of correlation was found between FIB concentrations and monitored stream tributary flows, which allowed modeling the behavior of the FIB with respect to the flow regime throughout the basin. Quantitative microbial risk assessment revealed specific stations with elevated infection risks from Escherichia coli exposure. This field-based study provides valuable insights into the relationship between the variables that influence FIB concentrations in a highly polluted river and the potential risk to the exposed population.

The Santiago–Guadalajara River Basin has an area of 10,016.46 km². The Metropolitan Area of Guadalajara, within the basin, is the second-largest city in the country, with more than 5 million inhabitants. The growth of the urban population, as well as industrial and agricultural activities with insufficient infrastructure for the sanitation of wastewater and its reuse, have caused environmental deterioration of surface waters and gradual depletion of groundwater resources. To assess the level of contamination in surface waters from the presence of heavy metals in the basin, a monthly monitoring campaign was carried out at 25 sampling stations located in the main and tributary streams from July 2021 to April 2022. The following decreasing sequence was found according to the mean concentration values: Fe > Al > Mn > B > Ba > Zn > As > Cu > Cr > Ni > Pb > Cd. The Heavy Metal Pollution Index (HPI) method was applied to assess the level of risk to aquatic life, finding an average global HPI value of 305.522 for the basin, which classifies it as in the critical contamination range. The results also reflect health risks due to the presence of As, Cd, and Ni in some monitored stations. It will be necessary to expand the monitoring network, identify the point and non-point sources of contamination, and implement measures for pollution control to protect aquatic life and human health due to the presence of heavy metals in the river.

The Santiago-Guadalajara River Basin has an area of 10,016.46 km2. The Metropolitan Area of Guadalajara, within the basin, is the second largest city in the country, with more than 5 million inhabitants. The growths of the urban population, as well as industrial and agricultural activities with insufficient infrastructure for the sanitation of wastewater and its reuse, have caused environmental deterioration of surface waters and gradual depletion of groundwater resources. To assess the level of contamination in surface waters from the presence of heavy metals in the basin, a monthly monitoring campaign was carried out at 25 sampling stations located in the main and tributary streams from July 2021 to April 2022. The following decreasing sequence was found according to the mean concentration values: Fe>Al>Mn>B >Ba>Zn>As>Cu>Cr>Ni>Cd. The Heavy Metal Pollution Index (HPI) method was applied to assess the level of risk to aquatic life, finding an average global HPI value of = 314.436 for the basin, which classifies it as in the critical contamination range. Regarding human health, results reflect concerning health risks due to presence of As, Cd, and Ni in some stations and require increased monitoring measures, as well as pollution control, to protect aquatic life and human health from heavy metal contamination.