Spontaneous fermentation is central to ancestral mezcal production, yet the bacterial and fungal communities associated with Agave cupreata must remain insufficiently characterized. This exploratory study described community composition and predicted functional profiles at three stages of a traditional fermentation defined by sugar depletion: 10 °Brix (0 h), 5 °Brix (72 h), and 2 °Brix (144 h). Ambient temperature ranged from 21.7 to 23.7 °C, must temperature from 28.5 to 29.9 °C, pH from 4.6 to 5.2, and relative humidity from 51.3% to 58.7%. At each stage, material collected from two wooden vats and three vertical positions was pooled into one composite sample. Bacterial 16S rRNA gene and fungal ITS1 amplicons were sequenced and analyzed using QIIME 2. At 10 °Brix, five dominant bacterial genera accounted for more than 93% of relative abundance. Lactic and acetic acid bacteria represented more than 91% at 5 °Brix, while Pediococcus, Lactiplantibacillus, and Loigolactobacillus were prominent at 2 °Brix. Seven fungal genera represented more than 98% of the initial profile, whereas Saccharomyces, Debaryomyces, and Maudiozyma accounted for more than 98% at 2 °Brix. PICRUSt2 predicted pathways related to carbohydrate degradation and fermentation, whereas FUNGuild assignments were predominantly saprotrophic at the later stages. Because one pooled sample was analyzed per stage, these patterns are descriptive and require validation in replicated fermentations. Despite these limitations, this study provides baseline information on the microbial communities associated with ancestral A. cupreata fermentation and identifies taxa and predicted functions that merit future isolation and experimental validation.

Pineapple (Ananas comosus L.) is a tropical fruit highly valued for its flavor, sweetness, aroma, and nutraceutical properties. The ‘Cayena Lisa’ cultivar is the most widely used for both fresh consumption and industrial purposes in Mexico. The municipalities of Tuxtepec and Loma Bonita, in the state of Oaxaca, produce around 582 thousand Mg of solid waste per year from fruit processing, to which the waste from plantations attacked by pests and diseases must be added. Consequently, these wastes must be processed in order to generate added value. Isolation of cysteine proteases from industrial residues is one possibility. In the present study, the parameters of the Mexican Official Standard for measuring pH (NOM-F-317-S-1978), total soluble solids (SST) (NMX-F-103-1982), and cysteine-protease activity in pineapple fruit processing residues at two stages of ripening over four months of harvest were used to determine whether there is a factor of quality attributes that correlates with the activity of this protein. In both ripening stages, cysteine-protease activity is higher in August. Regardless of the degree of ripening, peel and core are the best sources of cysteine-proteases. SST and pH values have no correlation with cysteine-protease activity, so they cannot be used as indicators of such activity. The findings show that ‘Cayena Lisa’ pineapple residues grown in Loma Bonita, Oaxaca, could be a good source of cysteine-proteases.

The devil fish (Hypostomus plecostomus) is a highly invasive exotic species due to its remarkable adaptability and the significant ecological damage it causes in aquatic ecosystems. This research aimed to extract, characterize, and evaluate the chemical purification of chitosan from fish tegumental shields, comparing it with chitosan obtained from shrimp exoskeletons. The biopolymer was purified through acid-alkaline hydrolysis (0.6 M HCl/25°C/1h and 0.4 M NaOH/28°C/3h), deacetylation (40% NaOH/110°C/5.5h), and depigmentation (38% NaClO/28°C/0.15h). Desmineralization, deproteinization, color chart, insoluble content, degree of acetylation, molecular weight, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) were evaluated. Chitosans from shrimp exoskeletons and devil fish tegumental shields obtained deproteinization percentages of 98.91 and 97.67%, desmineralization of 98.19 and 97.95%, deacetylation percentages of 82.031 and 83.346%, and molecular weights (MW) of 112.934 and 206.507 kDa respectively. FT-IR results identified an absorption band corresponding to C=O stretching in both samples, indicating the presence of carboxylic anion (-COO). Thermograms showed lower degradation temperatures (308°C) for commercial chitosan compared to that from devil fish (324°C). Devil fish tegumental shields offer chitosan similar to commercial sources, with significant economic potential and a 25% yield, potentially controlling invasive populations and restoring ecosystems.