Vermicomposting is a sustainable biotechnological process that transforms organic waste through the synergistic activity of earthworms, such as Eisenia fetida, and their associated microbiota. This study evaluated bacterial and physicochemical dynamics during the vermicomposting of bovine manure by analyzing the microbial composition of the substrate and the gut of E. fetida at three time points (weeks 0, 6, and 12). The V3–V4 region of the 16S rRNA gene was sequenced, and microbial diversity was characterized using QIIME2. Significant differences in alpha diversity (observed features, Shannon index, and phylogenetic diversity) and beta diversity indicated active microbial succession. Proteobacteria, Bacteroidota, and Actinobacteriota were the dominant phyla, with abundances varying across habitats and over time. A significant enrichment of Proteobacteria, Bacteroidota, and the genera Chryseolinea, Flavobacterium, and Sphingomonas was observed in the manure treatments. In contrast, Actinobacteriota, Firmicutes, and the genera Methylobacter, Brevibacillus, Enhygromyxa, and Bacillus, among others, were distinctive of the gut samples and contributed to their dissimilarity from the manure treatments. Simultaneously, the physicochemical parameters indicated progressive substrate stabilization and nutrient enrichment. Notably, the organic matter and total organic carbon contents decreased (from 79.47% to 47.80% and from 46.10% to 27.73%, respectively), whereas the total nitrogen content increased (from 1.70% to 2.23%); these effects reduced the C/N ratio, which is a recognized indicator of maturity, from 27.13 to 12.40. The macronutrient contents also increased, with final values of 1.41% for phosphorus, 1.50% for potassium, 0.89% for magnesium, and 2.81% for calcium. These results demonstrate that vermicomposting modifies microbial communities and enhances substrate quality, supporting its use as a biofertilizer for sustainable agriculture, soil restoration, and agrochemical reduction.

The emerging field of study of blood microbiota reveals the presence of bacteria in the blood of healthy animals. In endangered species such as the American bison (Bison bison), the analysis of this microbiota is crucial for conservation, as changes in these communities or the development of pathogens may affect their health and compromise herd viability. Here, we analyzed and compared the bacterial blood microbiota of healthy adult and juvenile bison in Mexico (Janos, Chihuahua), identifying those bacterial taxa with potential pathogenicity for these individuals. Blood samples were collected from 12 juvenile and 12 adult bison. The V3–V4 region of the 16S rRNA gene was amplified, and next-generation sequencing was subsequently performed on the Illumina NovaSeq platform. The bacterial taxa observed in the blood of these individuals (Firmicutes, Proteobacteria, Bacteroidota, Actinobacteria, Fusobacteriaceae, Lachnospiraceae, Oscillospiraceae, and Ruminococcaceae) have been previously reported to be abundant in the rumen and feces of bison. The most notable difference was observed for Mycoplasma wenyonii, which was significantly enriched in juveniles compared with adults. New sequencing technologies can be practically applied to improve the management and conservation of vulnerable species such as the American bison.

The gut microbiota plays a key role in the health of wild birds, reflecting the influence of diet, habitat, and social behavior. Migratory and highly gregarious species such as the yellow-headed blackbird (Xanthocephalus xanthocephalus) provide valuable opportunities to explore host–microbe–environment interactions within a One Health framework. During migration, birds are exposed to diverse environments and dietary sources, which can promote highly diverse intestinal microbial communities and facilitate transient acquisition of environmental microorganisms. Here, we present the first taxonomic characterization of the fecal bacterial microbiota of X. xanthocephalus in northern Mexico based on 16S rRNA gene sequencing of the V3–V4 region. In addition, we performed a conservative screening to assess whether any bacterial taxa tentatively assigned at the species level have been previously reported as human pathogens or as having potential zoonotic relevance. Fecal samples were collected noninvasively from communal roosts within an urban–agricultural landscape of the Comarca Lagunera region during a winter season. A highly diverse bacterial community (39 phyla, 369 families, and 1195 bacterial species) was identified. Firmicutes_D, Actinobacteriota, and Campylobacterota were the dominant phyla. Among the bacterial taxa tentatively assigned at the species level, only three have been reported to exhibit zoonotic potential in the literature; however, none corresponded to avian-adapted pathogens or bacterial species historically associated with major zoonotic outbreaks, and all were detected at very low relative abundances. Overall, our findings establish an initial microbiological baseline for X. xanthocephalus and underscore the role of migratory birds as indicators of environmental microbial dynamics rather than direct sources of zoonotic risk in semiarid regions of northern Mexico.

Urban pigeons (Columba livia) are widely distributed synanthropic birds closely associated with environments of intense human activity, raising interest in their role in urban microbial dynamics. Here, we characterized the fecal bacterial microbiota of urban pigeons from northern Mexico using 16S rRNA gene amplicon sequencing (V3–V4). A total of 1479 amplicon sequence variants (ASVs) were identified across five pooled samples. Alpha diversity varied among pools, with observed richness ranging from 228 to 514 ASVs. The bacterial community was dominated by Proteobacteria and Firmicutes, particularly Escherichia–Shigella and Enterococcus. PICRUSt2-based functional predictions suggested a predominance of predicted metabolic pathways related to carbohydrate degradation and energy acquisition. Conservative taxonomic screening identified 58 gut-associated taxa, including 15 bacteria previously reported in association with humans; however, only three (Clostridium perfringens, Enterococcus faecalis, and Proteus mirabilis) showed reported zoonotic associations, all at very low relative abundances (<0.07%). These findings indicate that the fecal bacterial communities characterized in this study were dominated by taxa commonly associated with the avian gastrointestinal tract, whereas taxa that could be conservatively linked to documented zoonotic reports represented only a minor fraction of the detected microbiota. Overall, the results contribute to a more ecologically informed understanding of urban pigeon-associated microbiota within a One Health framework.

Bovine-associated microbial communities play important roles in animal physiology, immune regulation, and mammary health. However, knowledge regarding bacterial populations associated with blood and milk remains limited in healthy dairy cattle exposed to different environmental conditions. In this study, we characterized and compared blood- and milk-associated bacterial communities from clinically healthy Holstein cows during summer and winter in an intensive commercial dairy production system located in northern Mexico using 16S rRNA metabarcoding. Significant differences in alpha and beta diversity metrics were observed according to sample type and season. Milk samples exhibited higher microbial richness and diversity than blood samples, and comparative analyses revealed significant differences in bacterial community composition between sample types and seasonal sampling periods. Bacterial communities were mainly dominated by Proteobacteria, Firmicutes, Actinobacteriota, and Bacteroidota. Differential abundance analyses identified genera associated with environmental exposure or opportunistic infections, including Staphylococcus, Streptococcus, Corynebacterium, Pseudomonas, and Acinetobacter. Overall, the observed bacterial community patterns varied according to sample type and seasonal environmental conditions, highlighting the complexity of host-associated microbial ecosystems in dairy cattle.