Anahí Martínez-Cárdenas

El norte de Sinaloa, México, alberga una rica diversidad de especies florales silvestres cuyo potencial fitoquímico no ha sido explorado previamente. Este estudio presenta de manera integral la evaluación de la actividad antioxidante y antimicrobiana, de extractos metanólicos y de acetato de etilo obtenidos de especies de flores silvestres: Albizia lebbeck, Boerhavia coccinea, Combretum indicum, Hylocereus undatus, Melampodium divaricatum, Vitex trifolia y Yucca schidigera. Los extractos se prepararon mediante extracción sólido-líquido asistida por ultrasonido. La actividad antioxidante se evaluó mediante ensayos DPPH y ABTS, así como la cuantificación de fenoles totales. Los resultados mostraron que el extracto metanólico de B. coccinea presentó la mayor actividad antioxidante (IC₅₀ DPPH = 16.4 ± 0.7 µg/mL; IC₅₀ ABTS = 75.1 ± 3.0 µg/mL), y el mayor contenido fenólico (326.6 ± 1.67 mg AG/g extracto). El extracto de metanol de C. Indicum también mostró actividad antioxidante destacada (IC₅₀ DPPH = 63.1 ± 2.5 µg/mL; IC₅₀ ABTS = 92.86 ± 3.7 µg/mL; 208.5 ± 9.1 mg AG/g extracto). La actividad antimicrobiana se determinó mediante el método de concentración mínima inhibitoria y de difusión en disco contra Staphylococcus aureus ATCC, Staphylococcus aureus MRSA, Salmonella Typhimurium, Escherichia coli ATCC y Escherichia coli EAEC, observándose halos de inhibición significativos en varios extractos. Los extractos, además, demostraron actividad protectora contra hemólisis de eritrocitos inducida por AAPH. Estos hallazgos evidencian que las flores silvestres del norte de Sinaloa constituyen una fuente prometedora de metabolitos secundarios con múltiples bioactividades, destacando especialmente B. coccinea y C. indicum como candidatos para estudios fitoquímicos más profundos y desarrollo de productos bioactivos naturales.

Background The family Phyllostomidae, encompassing a wide range of feeding strategies, is one of the most ecologically diverse groups of bats in the Americas. Within this family, nectarivorous bats of the subfamily Glossophaginae play a significant ecological role as pollinators. This study investigated the mitochondrial genome evolution of species in the Glossophaginae subfamily, focusing on selective pressures acting on their mitochondrial protein-coding genes (PCGs) compared with those of closely related frugivorous and insectivorous species in the family Phyllostomidae. Methods and results We sequenced the complete mitochondrial genomes of Glossophaga morenoi and Glossophaga mutica, revealing typical features such as AT-rich nucleotide composition and conserved gene order. Phylogenetic analyses based on PCGs confirmed the relationships of G. morenoi and G. mutica within the genus Glossophaga. We analyzed signals of selective pressures across mitochondrial PCGs using Ka/Ks (ω) values among species in the genus Glossophaga. Ka/Ks (ω) values were consistently < 1 across all studied genes, suggesting that signals of purifying selection act in the mitochondrial genome. Moreover, with RELAX analysis, we found signals of a shift in selection pressures in ATP8, COX1, CYTB, and ND5 PCGs of the subfamily Glossophaginae in comparison to those of Stenodermatinae (frugivorous) and Lonchorhininae (insectivorous) bats. Additionally, MEME selection analysis of these four genes, with a focus on the subfamily Glossophaginae, revealed signatures of positive selection in individual sites of PCGs, which could be associated with adaptations to their nectarivorous diet. Conclusions We found conserved mitogenomes in the genus Glossophaga, yet our results reveal significant signatures of selection that may reflect adaptations to the metabolic demands of a nectarivorous lifestyle in Glossophaginae bats.

The fringe-lipped frog-eating bat Trachops coffini inhabits tropical and semitropical rainforests from Mexico to Brazil. In this study, we sequenced and assembled the complete mitochondrial genome of T. coffini. The entire mitogenome is a circular molecule, 16,960 bp in total length that contains 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNA genes, and one D-loop or control region (CR). The overall base composition is A = 32.43%, G = 13.43%, C = 24.26%, and T = 29.87%, with A + T content = 62.31%. A phylogenetic tree reconstructed using the 13 PCGs that included 59 taxa recovered T. coffini as a taxon sister to a fully-supported clade containing the genera Tonatia, Lophostoma, and Phyllostomus.

Microbial mats are microbial communities capable of recycling the essential elements of life and considered to be the oldest evidence of microbial communities on Earth. Due to their uniqueness and limited sampling material, analyzing their metabolomic profile in different seasons or conditions is challenging. In this study, microbial mats from a small pond in the Cuatro Cienegas Basin in Coahuila, Mexico, were collected in wet and dry seasons. In addition to these samples, mesocosm experiments from the wet samples were set. These mats are elastic and rise after heavy rainfall by forming gas domes structures known as “Archean domes”, by the outgassing of methanogenic bacteria, archaea, and sulfur bacteria. Extracts from all mats and mesocosms were subjected to untargeted mass spectrometry‐based metabolomics and molecular networking analysis. Interestingly, each mat showed high chemical diversity that may be explained by the temporal dynamic processes in which they were sampled.

Mangrove sediment ecosystems in the coastal areas of the Yucatan peninsula are unique environments, influenced by their karstic origin and connection with the world’s largest underground river. The microbial communities residing in these sediments are influenced by the presence of mangrove roots and the trading chemistry for communication between sediment bacteria and plant roots can be targeted for secondary metabolite research. To explore the secondary metabolite production potential of microbial community members in mangrove sediments at the “El Palmar” natural reserve in Sisal, Yucatan, a combined meta-omics approach was applied. The effects of a cultivation medium reported to select for actinomycetes within mangrove sediments’ microbial communities was also analyzed. The metabolome of the microbial communities was analyzed by high-resolution liquid chromatography-tandem mass spectrometry, and molecular networking analysis was used to investigate if known natural products and their variants were present. Metagenomic results suggest that the sediments from “El Palmar” harbor a stable bacterial community independently of their distance from mangrove tree roots. An unexpected decrease in the observed abundance of actinomycetes present in the communities occurred when an antibiotic-amended medium considered to be actinomycete-selective was applied for a 30-day period. However, the use of this antibiotic-amended medium also enhanced production of secondary metabolites within the microbial community present relative to the water control, suggesting the treatment selected for antibiotic-resistant bacteria capable of producing a higher number of secondary metabolites. Secondary metabolite mining of “El Palmar” microbial community metagenomes identified polyketide synthase and non-ribosomal peptide synthetases’ biosynthetic genes in all analyzed metagenomes. The presence of these genes correlated with the annotation of several secondary metabolites from the Global Natural Product Social Molecular Networking database. These results highlight the biotechnological potential of the microbial communities from “El Palmar”, and show the impact selective media had on the composition of communities of actinobacteria.

A collection of 29 cultivable fungal strains isolated from deep-sea sediments of the Gulf of Mexico were cultivated under the “one strain, many compounds” approach to explore their chemical diversity and antimicrobial potential. From the 87 extracts tested, over 50% showed antimicrobial activity, and the most active ones were those from cultures grown at 4 °C in darkness for 60 days (resembling deep-sea temperature). PCA analysis of the LC-MS data of all the extracts confirmed that culture temperature is the primary factor in the variation of the 4462 metabolite features, accounting for 21.3% of the variation. The bioactivity-guided and conventional chemical studies of selected fungal strains allowed the identification of several active and specialized metabolites. Finally, metabolomics analysis by GNPS molecular networking and manual dereplication revealed the biosynthetic potential of these species to produce interesting chemistry. This work uncovers the chemical and biological study of marine-derived fungal strains from deep-sea sediments of the Gulf of Mexico.

The marine-facultative Aspergillus sp. MEXU 27854, isolated from the Caleta Bay in Acapulco, Guerrero, Mexico, has provided an interesting diversity of secondary metabolites, including a series of rare dioxomorpholines, peptides, and butyrolactones. Here, we report on the genomic data, which consists of 11 contigs (N50~3.95 Mb) with a ~30.75 Mb total length of assembly. Genome annotation resulted in the prediction of 10,822 putative genes. Functional annotation was accomplished by BLAST searching protein sequences with different public databases. Of the predicted genes, 75% were assigned gene ontology terms. From the 67 BGCs identified, ~60% belong to the NRPS and NRPS-like classes. Putative BGCs for the dioxomorpholines and other metabolites were predicted by extensive genome mining. In addition, metabolomic molecular networking analysis allowed the annotation of all isolated compounds and revealed the biosynthetic potential of this fungus. This work represents the first report of whole-genome sequencing and annotation from a marine-facultative fungal strain isolated from Mexico.