Adriana Ambrosini

Quality control of drinking water is essential for safeguarding public health, particularly in densely populated urban environments. Environmental microbiological monitoring can complement conventional surveillance by providing deeper insights into the dissemination of pathogens and antimicrobial resistance genes within aquatic systems. In this study, we assessed the quality of wastewater and treated water from two urban water supply systems, representing the southern and northern regions of Porto Alegre, Rio Grande do Sul, Brazil, across four climatic seasons between 2024 and 2025. Fifteen water samples were analyzed, including raw water from Guaíba Lake and treated water collected from public distribution points. The Water Quality Index was calculated, microbiological indicators were quantified, and carbapenem resistance genes were detected using molecular assays. Most treated water samples complied with established bacteriological standards; however, the bla_OXA-48-like gene was recurrently detected in both wastewater and treated water. No resistance genes were identified during the summer, whereas the bla_VIM gene was detected exclusively in spring samples. The presence of carbapenem resistance genes in the absence of cultivable coliforms suggests the persistence of extracellular DNA or viable but non-culturable bacteria, highlighting limitations inherent to conventional microbiological monitoring. Integrating classical microbiological methods with molecular assays enables a more comprehensive assessment of water quality and strengthens evidence-based decision-making within a One Health framework.

Quality control of drinking water is essential for safeguarding public health, particularly in densely populated urban environments. Environmental microbiological monitoring can enhance traditional surveillance by providing deeper insights into the dissemination of pathogens and antimicrobial resistance genes in aquatic systems. In this study, we evaluated the quality of wastewater and treated water from two urban water supply systems, representing the southern and northern regions of Porto Alegre, Rio Grande do Sul, Brazil, across four climatic seasons between 2024 and 2025. Fifteen water samples, comprising raw water from Guaíba Lake and treated water from public distribution points, were analyzed. The Water Quality Index was calculated, microbiological indicators were quantified, and carbapenem resistance genes were detected using molecular assays. Most treated water samples complied with bacteriological standards; however, the blaOXA-48-like gene was recurrently identified in both wastewater and treated water. No resistance genes were detected during the summer, while the blaVIM gene appeared exclusively in spring samples. The detection of carbapenem resistance genes in the absence of cultivable coliforms suggests the persistence of extracellular DNA or viable but non-culturable bacteria, underscoring limitations of conventional microbiological monitoring. Integrating classical microbiological methods with molecular assays provides a more comprehensive evaluation of water quality and supports decision-making within a One Health framework.

Azospirillum sp. strain Sp245^T, originally identified as belonging to Azospirillum brasilense , is recognized as a plant-growth-promoting rhizobacterium due to its ability to fix atmospheric nitrogen and to produce plant-beneficial compounds. Azospirillum sp. Sp245^T and other related strains were isolated from the root surfaces of different plants in Brazil. Cells are Gram-negative, curved or slightly curved rods, and motile with polar and lateral flagella. Their growth temperature varies between 20 to 38 °C and their carbon source utilization is similar to other Azospirillum species. A preliminary 16S rRNA sequence analysis showed that the new species is closely related to A. brasilense Sp7^T and A. formosense CC-Nfb-7^T. Housekeeping genes revealed that Azospirillum sp. Sp245^T, BR 12001 and Vi22 form a separate cluster from strain A. formosense CC-Nfb-7^T, and a group of strains closely related to A. brasilense Sp7^T. Overall genome relatedness index (OGRI) analyses estimated based on average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) between Azospirillum sp. Sp245^T and its close relatives to other Azospirillum species type strains, such as A. brasilense Sp7^T and A. formosense CC-Nfb-7^T , revealed values lower than the limit of species circumscription. Moreover, core-proteome phylogeny including 1079 common shared proteins showed the independent clusterization of A. brasilense Sp7^T, A. formosense CC-Nfb-7^T and Azospirillum sp. Sp245^T, a finding that was corroborated by the genome clustering of OGRI values and housekeeping phylogenies. The DNA G+C content of the cluster of Sp245^T was 68.4–68.6 %. Based on the phylogenetic, genomic, phenotypical and physiological analysis, we propose that strain Sp245^T together with the strains Vi22 and BR12001 represent a novel species of the genus Azospirillum , for which the name Azospirillum baldaniorum sp. nov. is proposed. The type strain is Sp245^T (=BR 11005^T=IBPPM 219^T) (GCF_007827915.1, GCF_000237365.1, and GCF_003119195.2).

Three facultatively anaerobic endospore-forming bacteria were isolated from the rhizosphere of sunflowers grown in fields of Rio Grande do Sul State, Brazil. The designated type strain P26E^T was previously identified as a sunflower growth promoting bacterium and is able to fix nitrogen and to excrete ammonia. According to analyses of 16S rRNA gene sequences, P26E^T presented similarity values above 98.8% in relation to Paenibacillus azotifigens NF2-4-5^T, Paenibacillus graminis RSA19^T, Paenibacillus jilunlii Be17^T, Paenibacillus salinicaeni LAM0A28^T, and Paenibacillus sonchi X19-5^T. Phylogenetic reconstructions based on 16S rRNA gene and core proteome data showed that the strains P26E^T, P3E and P32E form a distinct clade, which did not include any type strain of the currently described Paenibacillus species. Also, genomic comparisons using average nucleotide identity (ANI), Orthologous ANI and in silico DNA–DNA hybridization revealed similarity ranges below the recommended thresholds when the three isolates from sunflower were compared to their close relatives. The DNA G + C content of strain P26E^T was determined to be 49.4 mol%. The major cellular fatty acids are anteiso-C_15:0 and iso-C_15:0, representing about 58 and 14% of the total fatty acids in P26E^T, respectively. Based on different taxonomic genomic metrics, phylogeny, and phenotypic data, we propose that strain P26E^T (= DSM 102269 = BR10509) represents a novel species within the genus Paenibacillus, for which the name Paenibacillus helianthi sp. nov. is proposed.

Paenibacillus riograndensisSBR5^T, a nitrogen-fixing Gram-positive rhizobacterium isolated from a wheat field in the south of Brazil, has a great potential for agricultural applications due to its plant growth promotion effects. Here we present the draft genome sequence ofP. riograndensisSBR5^T. Its 7.37-Mb genome encodes determinants of the diazotrophic lifestyle and plant growth promotion, such as nitrogen fixation, antibiotic resistance, nitrate utilization, and iron uptake.

A 16S rRNA gene PCR-based assay was developed aiming at a fast molecular diagnostic method to differentiate the two phylogenetically closely related species Bradyrhizobium japonicum and B. elkanii, isolated from soybean nodules, in order to identify those more competitive and comprising greater nitrogen fixation ability for use in the formulation of commercial inoculants. The assay used was able to discriminate ten reference strains belonging to these two Bradyrhizobium species, as well as to efficiently identify 37 strains isolated from fields cultivated with soybean.