Plant growth-promoting bacteria (PGPBs) offer a sustainable alternative for enhancing crop productivity in low-fertility tropical soils. In this study, 30 bacterial isolates were screened in vitro for multiple PGP traits, including phosphate solubilization (from aluminum phosphate—AlPO₄ and thermophosphate), potassium release from phonolite rock, siderophore production, indole-3-acetic acid (IAA) synthesis, ACC deaminase activity, and antagonism against Fusarium spp. Statistical analysis revealed significant differences (p < 0.05) among the isolates. The most efficient isolates demonstrated a solubilization capacity ranging from 24.0 to 45.2 mg L⁻¹ for thermophosphate and 21.7 to 23.5 mg L⁻¹ for potassium from phonolite. Among them, Pseudomonas azotoformans K22 showed the highest AlPO₄ solubilization (16.6 mg L⁻¹). IAA production among the isolates varied widely, from 1.34 to 9.65 µg mL⁻¹. Furthermore, 17 isolates produced carboxylate-type siderophores, and only Pseudomonas aeruginosa SS183 exhibited ACC deaminase activity, coupled with strong antifungal activity (91% inhibition). A composite performance index identified P. azotoformans K22, E. hormaechei SS150, S. sciuri SS120, and B. cereus SS18 and SS17 as the most promising isolates. This study provides a valuable foundation for characterizing plant growth-promoting traits and identifies key candidates for future validation and the development of microbial consortia.

Rivers provide essential water resources for humans. However, appear to be reservoirs of antimicrobial-resistant genes and dispersal routes of resistant pathogens because human activities promptly influence them. Sediments are the most propitious substrates for bacteria survival and can act as an antimicrobial reservoir. Three sediment samples were collected upstream of the water catchment point of the Guandu Water Treatment Plant (ETA Guandu) to evaluate microbial diversity and antimicrobial resistance genes to sulfonamide (sul1, sul2), tetracycline (tetA, tetB) and beta-lactam (blaCTX-M, blaoxa24 and blaoxa58) by PCR. The most abundant phylum in all samples was Proteobacteria, which was also the most dominant in sediments presenting a pattern already reported in the literature for diversity in tropical and temperate climate rivers. Sulfonamide resistance genes were detected in all samples. The blaCTX-M gene was detected only in one sample, and tetA, tetB, blaoxa24 and blaoxa58 genes were not found in any sample. The presence of antimicrobial resistance genes sul1, sul2, and blaCTX-M indicate that sediments can act as a reservoir of resistance. These findings will provide new data about the bacterial community and antimicrobial resistance genes in Brazilians river sediments.

Antimicrobial resistance is a global public health concern that requires an integrated approach including human, animal and environmental health. Agricultural environments, such as soil, animal waste and irrigation water, play crucial roles in the dynamics of antimicrobial resistance, as they act as reservoirs and pathways for disseminating resistance determinants. However, these agricultural environments are still often underestimated or neglected in many studies. This study aimed to address antimicrobial resistance in agricultural environments in Brazil and summarize the current state of knowledge about this issue in the country. Google Scholar, Google, ISI Web of Knowledge and Web of Science databases were searched for Portuguese, English and Spanish articles addressing antimicrobial resistance in agricultural environments in Brazil published through 2023. Different terms were used, and the findings were categorized according to the research questions posed. A total of 36 articles were found, 20 of which focused on antimicrobial resistance in animal waste from livestock production, 13 addressed antimicrobial resistance in agricultural soils, two considered both environments, and only one considered antimicrobial resistance associated with irrigation water in different agricultural environments. In all studies, diverse classes of resistant bacteria and antimicrobial resistance genes and mobile genetic elements were detected. However, the number of articles addressing this topic in Brazilian agricultural environments - in animal waste, followed by soils and, to a lesser degree, irrigation water - is still quite limited, revealing significant gaps to be filled. Therefore, it is essential to conduct more studies on antimicrobial resistance in these environments to elucidate their roles as reservoirs and sources of antimicrobial resistance and assess the risks to public health.

Wastewater treatment plants (WWTPs) are important interfaces for the persistence and dissemination of antimicrobial resistance genes (ARGs) in the environment. This study investigated colistin resistance and the presence of mobile colistin resistance (mcr) genes in Enterobacterales isolated from a poultry slaughterhouse WWTP in Brazil. Samples were collected from raw sewage, an equalization tank, and treated effluent. A total of 27 Enterobacter spp. isolates were identified, of which 70.4% showed resistance to colistin (MIC range: 2 to ≥512 mg/L). PCR screening detected mcr-1 in two isolates and mcr-10 in three isolates distributed across all treatment stages, including the final effluent. Whole-genome sequencing of a representative isolate from treated effluent identified Enterobacter vonholyi ST3343, carrying a plasmid-borne mcr-10 gene on an ~107 kb IncFII(Yp) plasmid, along with additional resistance determinants. Phylogenetic analysis supported the classification of this gene as a novel allele, mcr-10.6. The persistence of a clonal lineage harboring mcr-10.6 throughout the treatment system indicates that conventional wastewater treatment may not effectively eliminate clinically relevant ARGs. These findings highlight treated effluent as a potential route for environmental dissemination of colistin resistance and reinforce the need for improved monitoring and mitigation strategies within a One Health framework.