Bacterial communities in fecal samples of myotis chiloensis from Southern, Chile / Comunidades bacterianas presentes en muestras fecales de myotis chiloensis en el sur de Chile

SUMMARY: The insectivorous bat Myotis chiloensis is endemic of South America. Even though potentially pathogenic bacterial species of Mycoplasma have been reported from this species, there are no further studies regarding the bacterial communities they harbor. This may provide important insights for the better understanding of its ecology, diet and implications in cross-species pathogens transmission. Here we report a first survey on bacterial communities of M. chiloensis based on metagenomic analysis of fecal samples. We found that taxonomic profile is dominated by Proteobacteria (23.7 to 57.7 %) and Firmicutes (11.8 to 61.6 %), which main families are represented by Burkholderiaceae- Enterobacteriaceae and Veillonellaceae-Bacillaceae, respectively. Phyla Bacteroidetes, Actinobacteria, Cyanobacteria, Planctomycetes and Acidobacteria were also present with abundance above 1 % of the total reads. Variations among individuals could be observed at genus level and no significant differences were found between sex groups regarding taxonomic profiles and diversity. Potentially pathogenic species were also detected in all the samples, including Staphylococcus aureus and Clostridium perfringens. Our results highlight the significance M. chiloensis as a reservoir of pathogenic bacteria and its microbiota as an interesting ecological model due to its wide distribution. Further metagenomic studies are necessary for a better understanding of M. chiloensis diet and its host-symbiont relationships.

RESUMEN: El murciélago insectívoro Myotis chiloensis es endémico de América del Sur. A pesar de que en esta especie se han reportado bacterias potencialmente patógenas tipo Mycoplasma, no existen estudios sobre sus comunidades bacterianas, lo cual podría proporcionar información importante para una mejor comprensión de su ecología, dieta e implicaciones en la transmisión de patógenos. En el presente trabajo se realiza una descripción de las comunidades bacterianas del murciélago M. chiloensis basada en análisis metagenómico de muestras fecales. El perfil taxonómico encontradofue dominado por Proteobacterias (23,7-57,7 %) y Firmicutes (11,8-61,6 %), cuyas principales familias fueron representadas por Burkholderiaceae-Enterobacteriaceae y Veillonellaceae-Bacillaceae, respectivamente. También se encontraron los filos Bacteroidetes, Actinobacteria, Cyanobacteria, Planctomycetes y Acidobacteria con una abundancia superior al 1 %. Se observaron variaciones entre los individuos a nivel de género, sin diferencias significativas de los perfiles taxonómicos y diversidad según sexo. Se detectaron especies potencialmente patógenas en todas las muestras, entre ellos Staphylococcus aureus y Clostridium perfringens. Nuestros resultados destacan la importancia de M. chiloensis como un reservorio de bacterias patógenas y el estudio de su microbiota como un modelo ecológico debido a su amplia distribución. Más estudios metagenómicos son necesarios para comprender la dieta de M. chiloensis y sus relaciones huésped-simbionte.

Genomic and Metabolomic Analysis of Antarctic Bacteria Revealed Culture and Elicitation Conditions for the Production of Antimicrobial Compounds.

Concern about finding new antibiotics against drug-resistant pathogens is increasing every year. Antarctic bacteria have been proposed as an unexplored source of bioactive metabolites; however, most biosynthetic gene clusters (BGCs) producing secondary metabolites remain silent under common culture conditions. Our work aimed to characterize elicitation conditions for the production of antibacterial secondary metabolites from 34 Antarctic bacterial strains based on MS/MS metabolomics and genome mining approaches. Bacterial strains were cultivated under different nutrient and elicitation conditions, including the addition of lipopolysaccharide (LPS), sodium nitroprusside (SNP), and coculture. Metabolomes were obtained by HPLC-QTOF-MS/MS and analyzed through molecular networking. Antibacterial activity was determined, and seven strains were selected for genome sequencing and analysis. Biosynthesis pathways were activated by all the elicitation treatments, which varies among strains and dependents of culture media. Increased antibacterial activity was observed for a few strains and addition of LPS was related with inhibition of Gram-negative pathogens. Antibiotic BGCs were found for all selected strains and the expressions of putative actinomycin, carotenoids, and bacillibactin were characterized by comparison of genomic and metabolomic data. This work established the use of promising new elicitors for bioprospection of Antarctic bacteria and highlights the importance of new "-omics" comparative approaches for drug discovery.