Biotechnological potential in agriculture of soil Antarctic microorganisms revealed by omics approach.

The biotechnological potential for agricultural applications in the soil in the thawing process on Whalers Bay, Deception Island, Antarctica was evaluated using a metagenomic approach through high-throughput sequencing. Approximately 22.70% of the sequences were affiliated to the phyla of the Bacteria dominion, followed by 0.26% to the Eukarya. Proteobacteria (Bacteria) and Ascomycota (Fungi) were the most abundant phyla. Thirty-two and thirty-six bacterial and fungal genera associated with agricultural biotechnological applications were observed. Streptomyces and Pythium were the most abundant genera related to the Bacteria and Oomycota, respectively. The main agricultural application associated with bacteria was nitrogen affixation; in contrast for fungi, was associated with phytopathogenic capabilities. The present study showed the need to use metagenomic technology to understand the dynamics and possible metabolic pathways associated with the microbial communities present in the soil sample in the process of thawing recovered from the Antarctic continent, which presented potential application in processes of agro-industrial interest.

Integrating whole genome sequencing and machine learning for predicting antimicrobial resistance in critical pathogens: a systematic review of antimicrobial susceptibility tests.

Background: Infections caused by antibiotic-resistant bacteria pose a major challenge to modern healthcare. This systematic review evaluates the efficacy of machine learning (ML) approaches in predicting antimicrobial resistance (AMR) in critical pathogens (CP), considering Whole Genome Sequencing (WGS) and antimicrobial susceptibility testing (AST). Methods: The search covered databases including PubMed/MEDLINE, EMBASE, Web of Science, SCOPUS, and SCIELO, from their inception until June 2024. The review protocol was officially registered on PROSPERO (CRD42024543099). Results: The review included 26 papers, analyzing data from 104,141 microbial samples. Random Forest (RF), XGBoost, and logistic regression (LR) emerged as the top-performing models, with mean Area Under the Receiver Operating Characteristic (AUC) values of 0.89, 0.87, and 0.87, respectively. RF showed superior performance with AUC values ranging from 0.66 to 0.97, while XGBoost and LR showed similar performance with AUC values ranging from 0.83 to 0.91 and 0.76 to 0.96, respectively. Most studies indicate that integrating WGS and AST data into ML models enhances predictive performance, improves antibiotic stewardship, and provides valuable clinical decision support. ML shows significant promise for predicting AMR by integrating WGS and AST data in CP. Standardized guidelines are needed to ensure consistency in future research.

Effects of Dietary Agavin on the Gut Microbiota of the Nile Tilapia (Oreochromis niloticus) Reared at High Densities.

High-density stress can lead to dysbiotic microbiota, affecting the organism's metabolic, and protective functions. Agavin is a fructan with prebiotic properties that regulate the gut microbiota by promoting the growth of beneficial bacteria. This study evaluated the effect of agavin on the gut microbiota using Next-Generation Sequencing (NGS) and its correlation with the growth parameters. Four groups of fish were fed different diets: a control diet (negative and positive control), without agavin supplementation, and two experimental diets supplemented with agavin at 20 g kg-1 and 40 g kg-1. Nile tilapias (1.04 g ± 0.01 g) were fed for 110 days. After 90 days of feeding, fish were subjected to high-density stress (63 kg m-3) for 20 days, except for the negative control. NGS detected 1579 different operational taxonomic units in the samples. In the correlation analysis of growth parameters, the families Vibrionaceae and Methyloligillaceae showed a positive correlation with fish growth parameters, these results may serve to know the relation of agavin and microbiota on the growth performance, as well as the metabolic activities of families in tilapia. Furthermore, high-density stress and agavin supplementation modify the gut microbiota in tilapia. At a low-density, supplementation with 20 g kg-1 agavin promoted the growth of the potentially beneficial families Sphingomonadaceae, Oxalobacteriaceae, and Chitinophagaceae; at high densities, reduced the abundance of pathogenic families (Vibrionaceae and Aeromonadaceae). These results suggest that, under stress conditions, agavin can stimulate the growth of potentially beneficial bacteria and reduce the growth of potentially pathogenic bacteria, suggesting its potential use as a prebiotic in aquaculture.

Lake Bacterial Communities in North Patagonian Andes: The Effect of the Nothofagus pumilio Treeline.

One of the most noticeable environmental discontinuities in mountains is the transition that exists in vegetation below and above the treeline. In the North Patagonian Andean lakes (between 900 and 1950 m a.s.l.), we analyzed the bacterial community composition of lakes in relation to surrounding vegetation (erected trees, krummholz belt, and bare rocks), dissolved organic carbon (DOC), and total dissolved nutrients (nitrogen, TDN and phosphorus, TDP). We observed a decrease in DOC, TDP, and TDN concentrations with altitude, reflecting shifts in the source inputs entering the lakes by runoff. Cluster analysis based on bacterial community composition showed a segregation of the lakes below treeline, from those located above. This first cluster was characterized by the cyanobacteria Cyanobium PCC-6307, while in the krummholz belt and bare rocks, bacterial communities were dominated by Actinobacteria hgcl-clade and Proteobacteria (Sandarakinorhabdus and Rhodovarius), with the presence of pigments such as actinorhodopsin, carotenoids, and bacteriochlorophyll a. The net relatedness index (NRI), which considers the community phylogenetic dispersion, showed that lakes located on bare rocks were structured by environmental filtering, while communities of lakes below treeline were structured by species interactions such as competition. Beta-diversity was higher among lakes below than among lakes located above the treeline. The contribution of species turnover was more important than nestedness. Our study brings light on how bacterial communities may respond to changes in the surrounding vegetation, highlighting the importance of evaluating different aspects of community structure to understand metacommunity organization.

Acidophilic sulphate-reducing bacteria: Diversity, ecophysiology, and applications.

Acidophilic sulphate-reducing bacteria (aSRB) are widespread anaerobic microorganisms that perform dissimilatory sulphate reduction and have key adaptations to tolerate acidic environments (pH <5.0), such as proton impermeability and Donnan potential. This diverse prokaryotic group is of interest from physiological, ecological, and applicational viewpoints. In this review, we summarize the interactions between aSRB and other microbial guilds, such as syntrophy, and their roles in the biogeochemical cycling of sulphur, iron, carbon, and other elements. We discuss the biotechnological applications of aSRB in treating acid mine drainage (AMD, pH <3), focusing on their ability to produce biogenic sulphide and precipitate metals, particularly in the context of utilizing microbial consortia instead of pure isolates. Metal sulphide nanoparticles recovered after AMD treatment have multiple potential technological uses, including in electronics and biomedicine, contributing to a cost-effective circular economy. The products of aSRB metabolisms, such as biominerals and isotopes, could also serve as biosignatures to understand ancient and extant microbial life in the universe. Overall, aSRB are active components of the sulphur and carbon cycles under acidic conditions, with potential natural and technological implications for the world around us.

Habitat specificity modulates the bacterial biogeographic patterns in the Southern Ocean.

Conceptual biogeographic frameworks have proposed that the relative contribution of environmental and geographical factors on microbial distribution depends on several characteristics of the habitat (e.g. environmental heterogeneity, species diversity, and proportion of specialist/generalist taxa), all of them defining the degree of habitat specificity, but few experimental demonstrations exist. Here, we aimed to determine the effect of habitat specificity on bacterial biogeographic patterns and assembly processes in benthic coastal ecosystems of the Southern Ocean (Patagonia, Falkland/Malvinas, Kerguelen, South Georgia, and King George Islands), using 16S rRNA gene metabarcoding. The gradient of habitat specificity resulted from a 'natural experimental design' provided by the Abatus sea urchin model, from the sediment (least specific habitat) to the intestinal tissue (most specific habitat). The phylogenetic composition of the bacterial communities showed a clear differentiation by site, driven by a similar contribution of geographic and environmental distances. However, the strength of this biogeographic pattern decreased with increasing habitat specificity: sediment communities showed stronger geographic and environmental divergence compared to gut tissue. The proportion of stochastic and deterministic processes contributing to bacterial assembly varied according to the geographic scale and the habitat specificity level. For instance, an increased contribution of dispersal limitation was observed in gut tissue habitat. Our results underscore the importance of considering different habitats with contrasting levels of specificity to better understand bacterial biogeography and assembly processes over oceanographic scales.

Metagenomic Analysis to Assess the Impact of Plant Growth-Promoting Rhizobacteria on Peanut (Arachis hypogaea L.) Crop Production and Soil Enzymes and Microbial Diversity.

Peanut production could be increased through plant growth-promoting rhizobacteria (PGPR). In this regard, the present field research aimed at elucidating the impact of PGPR on peanut yield, soil enzyme activity, microbial diversity, and structure. Three PGPR strains (Bacillus velezensis, RI3; Bacillus velezensis, SC6; Pseudomonas psychrophila, P10) were evaluated, along with Bradyrhizobium japonicum (BJ), taken as a control. PGPR increased seed yield by 8%, improving the radiation use efficiency (4-14%). PGPR modified soil enzymes (fluorescein diacetate activity by 17% and dehydrogenase activity by 28%) and microbial abundance (12%). However, PGPR did not significantly alter microbial diversity; nonetheless, it modified the relative abundance of key phyla (Actinobacteria > Proteobacteria > Firmicutes) and genera (Bacillus > Arthrobacter > Pseudomonas). PGPRs modified the relative abundance of genes associated with N-fixation and nitrification while increasing genes related to N-assimilation and N-availability. PGPR improved agronomic traits without altering rhizosphere diversity.

The Gut Microbiome of Two Wild Bumble Bee Species Native of South America: Bombus pauloensis and Bombus bellicosus.

South America is populated by a wide range of bumble bee species that represent an important source of biodiversity, supporting pollination services in natural and agricultural ecosystems. These pollinators provide unique specific microbial niches, populated by a wide number of microorganisms such as symbionts, environmental opportunistic bacteria, and pathogens. Recently, it was demonstrated how microbial populations are shaped by trophic resources and environmental conditions but also by anthropogenic pressure, which strongly affects microbes' functionality. This study is focused on the impact of different land uses (natural reserve, agroecosystem, and suburban) on the gut microbiome composition of two South American bumble bees, Bombus pauloensis and Bombus bellicosus. Gut microbial DNA extracted from collected bumble bees was sequenced on the Illumina MiSeq platform and correlated with land use. Nosema ceranae load was analyzed with qPCR and correlated with microbiome data. Significant differences in gut microbiome composition between the two wild bumble bee species were highlighted, with notable variations in α- and ß-diversity across study sites. Bombus bellicosus showed a high abundance of Pseudomonas, a genus that includes environmental saprobes, and was found to be the second major taxa populating the gut microbiome, probably indicating the vulnerability of this host to environmental pollution. Pathogen analysis unveils a high prevalence of N. ceranae, with B. bellicosus showing higher susceptibility. Finally, Gilliamella exhibited a negative correlation with N. ceranae, suggesting a potential protective role of this commensal taxon. Our findings underscore the importance of considering microbial dynamics in pollinator conservation strategies, highlighting potential interactions between gut bacteria and pathogens in shaping bumble bee health.

Diversity of bacterial communities in wetlands of Calakmul Biosphere Reserve: a comparative analysis between conserved and semi-urbanized zones in pre-Mayan Train era.

BACKGROUND: The Calakmul Biosphere Reserve (CBR) is known for its rich animal and plant biodiversity, yet its microbial communities remain largely unknown. The reserve does not possess permanent bodies of water; nevertheless, seasonal depressions associated with fractures create wetlands, known locally as aguadas. Given the recent construction of the Maya train that crosses the CRB, it is essential to assess the biodiversity of its microorganisms and recognize their potential as a valuable source of goods. This evaluation is pivotal in mitigating potential mismanagement of the forest ecosystem. To enhance comprehension of microbial communities, we characterized the microbiota in three different wetlands. Ag-UD1 and Ag-UD2 wetlands are located in a zone without human disturbances, while the third, Ag-SU3, is in a semi-urbanized zone. Sampling was carried out over three years (2017, 2018, and 2019), enabling the monitoring of spatiotemporal variations in bacterial community diversity. The characterization of microbiome composition was conducted using 16S rRNA metabarcoding. Concurrently, the genomic potential of select samples was examined through shotgun metagenomics. RESULTS: Statistical analysis of alpha and beta diversity indices showed significant differences among the bacterial communities found in undisturbed sites Ag-UD1 and Ag-UD2 compared to Ag-SU3. However, no significant differences were observed among sites belonging to the undisturbed area. Furthermore, a comparative analysis at the zone level reveals substantial divergence among the communities, indicating that the geographic location of the samples significantly influences these patterns. The bacterial communities in the CBR wetlands predominantly consist of genera from phyla Actinobacteria, Acidobacteria, and Proteobacteria. CONCLUSION: This characterization has identified the composition of microbial communities and provided the initial overview of the metabolic capacities of the microbiomes inhabiting the aguadas across diverse conservation zones. The three sites exhibit distinct microbial compositions, suggesting that variables such as chemical composition, natural and anthropogenic disturbances, vegetation, and fauna may play a pivotal role in determining the microbial structure of the aguadas. This study establishes a foundational baseline for evaluating the impact of climatic factors and human interventions on critical environments such as wetlands.

Optimization of lung tissue pre-treatment by bead homogenization for subsequent culturomics.

The discovery that the lung harbors a diverse microbiome, as revealed by next-generation sequencing, has significantly altered our understanding of respiratory health and disease. Despite the association between the lung microbiota and disease, the nature of their relationship remains poorly understood, and culture isolation of these microorganisms could help to determine their role in lung physiology. Current procedures for processing samples from the lower respiratory tract have been shown to affect the viability of microorganisms, so it is crucial to develop new methods to improve their survival. This study aimed to improve the isolation and characterization of lung microorganisms using a bead-beating homogenization method in a mouse model. Microsphere diameter and bead-beating time affected the survival of the microorganisms (E. coli, S. aureus and C. albicans). Using 2.3 mm diameter microspheres for 60 s of bead-beating promoted the survival of both bacteria and yeast strains. After intratracheal instillation of these microorganisms in mice, approximately 70% of the cells were recovered after the tissue homogenization. To assess the efficiency of the proposed method, the diversity of bacteria was compared between the homogenate and lung tissue samples. Ninety-one genera were detected in the lung tissue, and 63 in the homogenate. Bacterial genera detected in the homogenate represented 84% of the total abundance of the microbiota identified in the lung tissue. Taken together, these results demonstrate that the tissue homogenization process developed in this study recovered the majority of the microorganisms present in the lung. This study presents a bead-beating homogenization method for effective cultivation of lung tissue microorganisms, which may help to improve the understanding of host-microbe interactions in the lung.

A Proposal for the RNAome at the Dawn of the Last Universal Common Ancestor.

From the most ancient RNAs, which followed an RNY pattern and folded into small hairpins, modern RNA molecules evolved by two different pathways, dubbed Extended Genetic Code 1 and 2, finally conforming to the current standard genetic code. Herein, we describe the evolutionary path of the RNAome based on these evolutionary routes. In general, all the RNA molecules analysed contain portions encoded by both genetic codes, but crucial features seem to be better recovered by Extended 2 triplets. In particular, the whole Peptidyl Transferase Centre, anti-Shine-Dalgarno motif, and a characteristic quadruplet of the RNA moiety of RNAse-P are clearly unveiled. Differences between bacteria and archaea are also detected; in most cases, the biological sequences are more stable than their controls. We then describe an evolutionary trajectory of the RNAome formation, based on two complementary evolutionary routes: one leading to the formation of essentials, while the other complemented the molecules, with the cooperative assembly of their constituents giving rise to modern RNAs.

Microbiota diversity of three Brazilian native fishes during ice and frozen storage.

This study aimed to assess the bacterial microbiota involved in the spoilage of pacu (Piaractus mesopotamics), patinga (female Piaractus mesopotamics x male Piaractus brachypomus), and tambacu (female Colossoma macropomum × male Piaractus mesopotamics) during ice and frozen storage. Changes in the microbiota of three fish species (N = 22) during storage were studied through 16S rRNA amplicon-based sequencing and correlated with volatile organic compounds (VOCs) and metabolites assessed by nuclear magnetic resonance (NMR). Storage conditions (time and temperature) affected the microbiota diversity in all fish samples. Fish microbiota comprised mainly of Pseudomonas sp., Brochothrix sp., Acinetobacter sp., Bacillus sp., Lactiplantibacillus sp., Kocuria sp., and Enterococcus sp. The relative abundance of Kocuria, P. fragi, L. plantarum, Enterococcus, and Acinetobacter was positively correlated with the metabolic pathways of ether lipid metabolism while B. thermosphacta and P. fragi were correlated with metabolic pathways involved in amino acid metabolism. P. fragi was the most prevalent spoilage bacteria in both storage conditions (ice and frozen), followed by B. thermosphacta. Moreover, the relative abundance of identified Bacillus strains in fish samples stored in ice was positively correlated with the production of VOCs (1-hexanol, nonanal, octenol, and 2-ethyl-1-hexanol) associated with off-flavors. 1H NMR analysis confirmed that amino acids, acetic acid, and ATP degradation products increase over (ice) storage, and therefore considered chemical spoilage index of fish fillets.

Antibiotic resistant bacteria and antibiotic resistance genes as contaminants of emerging concern: Occurrences, impacts, mitigations and future guidelines.

Antibiotic resistance, driven by the proliferation of antibiotic resistance genes (ARGs) and antibiotic resistance bacteria (ARBs), has emerged as a pressing global health concern. Antimicrobial resistance is exacerbated by the widespread use of antibiotics in agriculture, aquaculture, and human medicine, leading to their accumulation in various environmental compartments such as soil, water, and sediments. The presence of ARGs in the environment, particularly in municipal water, animal husbandry, and hospital environments, poses significant risks to human health, as they can be transferred to potential human pathogens. Current remediation strategies, including the use of pyroligneous acid, coagulants, advanced oxidation, and bioelectrochemical systems, have shown promising results in reducing ARGs and ARBs from soil and water. However, these methods come with their own set of challenges, such as the need for elevated base levels in UV-activated persulfate and the long residence period required for photocatalysts. The future of combating antibiotic resistance lies in the development of standardized monitoring techniques, global collaboration, and the exploration of innovative remediation methods. Emphasis on combination therapies, advanced oxidation processes, and monitoring horizontal gene transfer can pave the way for a comprehensive approach to mitigate the spread of antibiotic resistance in the environment.

Taxonomic and functional characterization of biofilms from a photovoltaic panel reveals high genetic and metabolic complexity of the communities.

AIMS: Biofilms are complex microbial cell aggregates that attach to different surfaces in nature, industrial environments, or hospital settings. In photovoltaic panels (PVs), biofilms are related to significant energy conversion losses. In this study, our aim was to characterize the communities of microorganisms and the genes involved in biofilm formation. METHODS AND RESULTS: In this study, biofilm samples collected from a PV system installed in southeastern Brazil were analyzed through shotgun metagenomics, and the microbial communities and genes involved in biofilm formation were investigated. A total of 2030 different genera were identified in the samples, many of which were classified as extremophiles or producers of exopolysaccharides. Bacteria prevailed in the samples (89%), mainly the genera Mucilaginibacter, Microbacterium, Pedobacter, Massilia, and Hymenobacter. The functional annotation revealed >12 000 genes related to biofilm formation and stress response. Genes involved in the iron transport and synthesis of c-di-GMP and c-AMP second messengers were abundant in the samples. The pathways related to these components play a crucial role in biofilm formation and could be promising targets for preventing biofilm formation in the PV. In addition, Raman spectroscopy analysis indicated the presence of hematite, goethite, and ferrite, consistent with the mineralogical composition of the regional soil and metal-resistant bacteria. CONCLUSIONS: Taken together, our findings reveal that PV biofilms are a promising source of microorganisms of industrial interest and genes of central importance in regulating biofilm formation and persistence.

Optimizing next-generation sequencing efficiency in clinical settings: analysis of read length impact on cost and performance.

BACKGROUND: The expansion of sequencing technologies as a result of the response to the COVID-19 pandemic enabled pathogen (meta)genomics to be deployed as a routine component of surveillance in many countries. Scaling genomic surveillance, however, comes with associated costs in both equipment and sequencing reagents, which should be optimized. Here, we evaluate the cost efficiency and performance of different read lengths in identifying pathogens in metagenomic samples. We carefully evaluated performance metrics, costs, and time requirements relative to choices of 75, 150 and 300 base pairs (bp) read lengths in pathogen identification. RESULTS: Our findings revealed that moving from 75 bp to 150 bp read length approximately doubles both the cost and sequencing time. Opting for 300 bp reads leads to approximately two- and three-fold increases, respectively, in cost and sequencing time compared to 75 bp reads. For viral pathogen detection, the sensitivity median ranged from 99% with 75 bp reads to 100% with 150-300 bp reads. However, bacterial pathogens detection was less effective with shorter reads: 87% with 75 bp, 95% with 150 bp, and 97% with 300 bp reads. These findings were consistent across different levels of taxa abundance. The precision of pathogen detection using shorter reads was comparable to that of longer reads across most viral and bacterial taxa. CONCLUSIONS: During disease outbreak situations, when swift responses are required for pathogen identification, we suggest prioritizing 75 bp read lengths, especially if detection of viral pathogens is aimed. This practical approach allows better use of resources, enabling the sequencing of more samples using streamlined workflows, while maintaining a reliable response capability.

The piranha gut microbiome provides a selective lens into river water biodiversity.

Advances in omics technologies have enabled the in-depth study of microbial communities and their metabolic profiles from all environments. Here metagenomes were sampled from piranha (Serrasalmus rhombeus) and from river water from the Rio São Benedito (Amazon Basin). Shotgun metagenome sequencing was used to explore diversity and to test whether fish microbiomes are a good proxy for river microbiome studies. The results showed that the fish microbiomes were not significantly different from the river water microbiomes at higher taxonomic ranks. However, at the genus level, fish microbiome alpha diversity decreased, and beta diversity increased. This result repeated for functional gene abundances associated with specific metabolic categories (SEED level 3). A clear delineation between water and fish was seen for beta diversity. The piranha microbiome provides a good and representative subset of its river water microbiome. Variations seen in beta biodiversity were expected and can be explained by temporal variations in the fish microbiome in response to stronger selective forces on its biodiversity. Metagenome assembled genomes construction was better from the fish samples. This study has revealed that the microbiome of a piranha tells us a lot about its river water microbiome and function.

Hyperexpansion of genetic diversity and metabolic capacity of extremophilic bacteria and archaea in ancient Andean lake sediments.

BACKGROUND: The Andean Altiplano hosts a repertoire of high-altitude lakes with harsh conditions for life. These lakes are undergoing a process of desiccation caused by the current climate, leaving terraces exposed to extreme atmospheric conditions and serving as analogs to Martian paleolake basins. Microbiomes in Altiplano lake terraces have been poorly studied, enclosing uncultured lineages and a great opportunity to understand environmental adaptation and the limits of life on Earth. Here we examine the microbial diversity and function in ancient sediments (10.3-11 kyr BP (before present)) from a terrace profile of Laguna Lejía, a sulfur- and metal/metalloid-rich saline lake in the Chilean Altiplano. We also evaluate the physical and chemical changes of the lake over time by studying the mineralogy and geochemistry of the terrace profile. RESULTS: The mineralogy and geochemistry of the terrace profile revealed large water level fluctuations in the lake, scarcity of organic carbon, and high concentration of SO42--S, Na, Cl and Mg. Lipid biomarker analysis indicated the presence of aquatic/terrestrial plant remnants preserved in the ancient sediments, and genome-resolved metagenomics unveiled a diverse prokaryotic community with still active microorganisms based on in silico growth predictions. We reconstructed 591 bacterial and archaeal metagenome-assembled genomes (MAGs), of which 98.8% belonged to previously unreported species. The most abundant and widespread metabolisms among MAGs were the reduction and oxidation of S, N, As, and halogenated compounds, as well as aerobic CO oxidation, possibly as a key metabolic trait in the organic carbon-depleted sediments. The broad redox and CO2 fixation pathways among phylogenetically distant bacteria and archaea extended the knowledge of metabolic capacities to previously unknown taxa. For instance, we identified genomic potential for dissimilatory sulfate reduction in Bacteroidota and α- and γ-Proteobacteria, predicted an enzyme for ammonia oxidation in a novel Actinobacteriota, and predicted enzymes of the Calvin-Benson-Bassham cycle in Planctomycetota, Gemmatimonadota, and Nanoarchaeota. CONCLUSIONS: The high number of novel bacterial and archaeal MAGs in the Laguna Lejía indicates the wide prokaryotic diversity discovered. In addition, the detection of genes in unexpected taxonomic groups has significant implications for the expansion of microorganisms involved in the biogeochemical cycles of carbon, nitrogen, and sulfur. Video Abstract.

In treacherous waters: detection of colistin-resistant bacteria in water and plastic litter from a recreational estuary.

Colistin resistance poses a major therapeutic challenge and resistant strains have now been reported worldwide. However, the occurrence of such bacteria in aquatic environments is considerably less understood. This study aimed to isolate and characterize colistin-resistant strains from water and plastic litter collected in an urban recreational estuary. Altogether, 64 strains with acquired colistin resistance were identified, mainly Acinetobacter spp. and Enterobacter spp. From these, 40.6% were positive for at least one mcr variant (1-9), 26.5% harbored, extended-spectrum beta-lactamases, 23.4% harbored, sulfonamide resistance genes, and 9.3% harbored, quinolone resistance genes. merA, encoding mercury resistance, was detected in 10.5% of these strains, most of which were also strong biofilm producers. The minimum inhibitory concentration toward colistin was determined for the mcr-positive strains and ranged from 2 to ≥512 µg ml-1. Our findings suggest that Gram-negative bacteria highly resistant to a last-resort antimicrobial can be found in recreational waters and plastic litter, thereby evidencing the urgency of the One Health approach to mitigate the antimicrobial resistance crisis.

Potentially pathogenic bacteria in the plastisphere from water, sediments, and commercial fish in a tropical coastal lagoon: An assessment and management proposal.

Microplastics in aquatic ecosystems harbor numerous microorganisms, including pathogenic species. The ingestion of these microplastics by commercial fish poses a threat to the ecosystem and human livelihood. Coastal lagoons are highly vulnerable to microplastic and microbiological pollution, yet limited understanding of the risks complicates management. Here, we present the main bacterial groups, including potentially pathogenic species, identified on microplastics in waters, sediments, and commercial fish from Ciénaga Grande de Santa Marta (CGSM), the largest coastal lagoon in Colombia. DNA metabarcoding allowed identifying 1760 bacterial genera on microplastics, with Aeromonas and Acinetobacter as the most frequent and present in all three matrices. The greatest bacterial richness and diversity were recorded on microplastics from sediments, followed by waters and fish. Biochemical analyses yielded 19 species of potentially pathogenic culturable bacteria on microplastics. Aeromonas caviae was the most frequent and, along with Pantoea sp., was found on microplastics in all three matrices. Enterobacter roggenkampii and Pseudomonas fluorescens were also found on microplastics from waters and fish. We propose management strategies for an Early Warning System against microbiological and microplastic pollution risks in coastal lagoons, illustrated by CGSM. This includes forming inter-institutional alliances for research and monitoring, accompanied by strengthening governance and health infrastructures.

Vertical transfer of gut microbiota from dam to neonate calf in the early of life.

The aim of this study was to investigate the vertical transfer of microbiota from dams to the offspring. We studied a pair of 20 dams and its offspring. Maternal sources (colostrum, feces and vaginal secretion) and newborn fecal samples were analyzed using 16S rDNA amplicon sequencing on days 1, 3, 7, 14 and 28. Overall, newborns were maintained healthy and did not receive antimicrobial therapy. The Source Tracker analysis indicated that the newborn fecal microbiota was similar to colostrum and vaginal secretion from day 1 up to 7. However, an unknown source (probably from the environment) showed a gradual increase in its similarity with fecal samples from calves measured from day 3 to 28. The most abundant bacteria groups on meconium (day 1) and calf fecal samples on day 3 were Escherichia-Shigella and Clostridium, respectively. On day 7, the predominant genus were Bifidobacterium and Lactobacillus, while Fusobacterium was the most abundant genus on day 14, coinciding with the diarrhea peak. Faecalibacterium showed a gradual increase throughout the neonatal period. Maternal sources contribute to the neonatal microbiota, however other unknown sources (probably environment) had a strong influence on development of the gut microbiota later in the neonate period.