Microbial influence on blood pressure: unraveling the complex relationship for health insights.

Hypertension, a critical global health concern, is characterized by persistent high blood pressure and is a major cause of cardiovascular events. This perspective explores the multifaceted implications of hypertension, its association with cardiovascular diseases, and the emerging role of the gut microbiota. The gut microbiota, a dynamic community in the gastrointestinal tract, plays a pivotal role in hypertension by influencing blood pressure through the generation of antioxidant, anti-inflammatory, and short-chain fatty acids metabolites, and the conversion of nitrates into nitric oxide. Antihypertensive medications interact with the gut microbiota, impacting drug pharmacokinetics and efficacy. Prebiotics and probiotics present promising avenues for hypertension management, with prebiotics modulating blood pressure through lipid and cholesterol modulation, and probiotics exhibiting a general beneficial effect. Personalized choices based on individual factors are crucial for optimizing prebiotic and probiotic interventions. In conclusion, the gut microbiota's intricate influence on blood pressure regulation offers innovative perspectives in hypertension therapeutics, with targeted strategies proving valuable for holistic blood pressure management and health promotion.

Mobile resistome of microbial communities and antimicrobial residues from drinking water supply systems in Rio de Janeiro, Brazil.

Antibiotic resistance genes (ARGs) are widespread in the environment due to the overuse of antibiotics and other pollutants, posing a threat to human and animal health. In this study, we evaluated antimicrobial residues, bacterial diversity and ARGs in two important watersheds, Guandu and São João, that supply drinking water to Rio de Janeiro city, Brazil. In addition, tap water samples were collected from three different cities in Rio de Janeiro State, including the metropolitan area of Rio de Janeiro city. Clarithromycin, sulfamethoxazole and azithromycin were found in untreated water and drinking water in all samples. A greater abundance of Proteobacteria was observed in Guandu and São João watersheds, with most of the sequences belonging to the Gammaproteobacteria class. A plasmidome-focused metagenomics approach revealed 4881 (Guandu), 3705 (São João) and 3385 (drinking water) ARGs mainly associated with efflux systems. The genes encoding metallo-ß-lactamase enzymes (blaAIM, blaGIM, blaIMP, and blaVIM) were detected in the two watersheds and in drinking water samples. Moreover, we demonstrated the presence of the colistin resistance genes mcr-3 and mcr-4 (both watersheds) and mcr-9 (drinking water and Guandu) for the first time in Brazil. Our data emphasize the importance of introducing measures to reduce the disposal of antibiotics and other pollutants capable of promoting the occurrence and spread of the microbial resistome on aquatic environments and predicting possible negative impacts on human health.

Structure and function of a novel GH8 endoglucanase from the bacterial cellulose synthase complex of Raoultella ornithinolytica.

Cellulose synthesis in bacteria is a complex process involving the concerted action of several enzymes whose genes are often organized in operons. This process influences many fundamental physiological aspects such as bacteria and host interaction, biofilm formation, among others. Although it might sound contradictory, the participation of cellulose-degrading enzymes is critical to this process. The presence of endoglucanases from family 8 of glycosyl hydrolases (GH8) in bacterial cellulose synthase (Bcs) complex has been described in different bacteria, including the model organism Komagataeibacter xylinus; however, their role in this process is not completely understood. In this study, we describe the biochemical characterization and three-dimensional structure of a novel GH8 member from Raoultella ornithinolytica, named AfmE1, which was previously identified by our group from the metagenomic analysis of the giant snail Achatina fulica. Our results demonstrated that AfmE1 is an endo-ß-1,4-glucanase, with maximum activity in acidic to neutral pH over a wide temperature range. This enzyme cleaves cello-oligosaccharides with a degree of polymerization ≥ 5 and presents six glucosyl-binding subsites. The structural comparison of AfmE1 with other GH8 endoglucanases showed significant structural dissimilarities in the catalytic cleft, particularly in the subsite +3, which correlate with different functional mechanisms, such as the recognition of substrate molecules having different arrangements and crystallinities. Together, these findings provide new insights into molecular and structural features of evolutionarily conserved endoglucanases from the bacterial cellulose biosynthetic machinery.

Detection of human fecal contamination by nifH gene quantification of marine waters in the coastal beaches of Rio de Janeiro, Brazil.

The identification of fecal pollution in aquatic ecosystems is one of the requirements to assess the possible risks to human health. In this report, physicochemical parameters, Escherichia coli enumeration and Methanobrevibacter smithii nifH gene quantification were conducted at 13 marine waters in the coastal beaches of Rio de Janeiro, Brazil. The pH, turbidity, dissolved oxygen, temperature, and conductivity, carried out by mobile equipment, revealed varied levels due to specific conditions of the beaches. The bioindicators' enumerations were done by defined substrate method, conventional, and real-time PCR. Six marine beach sites (46 %) presenting E. coli levels in compliance with Brazilian water quality guidelines (<2500 MPN/100 mL) showed nifH gene between 5.7 × 109 to 9.5 × 1011 copies. L-1 revealing poor correlation between the two approaches. To our knowledge, this is the first inquiry in qPCR using nifH gene as a biomarker of human-specific sources of sewage pollution in marine waters in Brazil. In addition, our data suggests that alternative indicator nifH gene could be used, in combination with other markers, for source tracking studies to measure the quality of marine ecosystems thereby contributing to improved microbial risk assessment.

Archaeal and bacterial communities of heavy metal contaminated acidic waters from zinc mine residues in Sepetiba Bay.

Mining of metallic sulfide ore produces acidic water with high metal concentrations that have harmful consequences for aquatic life. To understand the composition and structure of microbial communities in acid mine drainage (AMD) waters associated with Zn mine tailings, molecular diversity of 16S genes was examined using a PCR, cloning, and sequencing approach. A total of 78 operational taxonomic units (OTUs) were obtained from samples collected at five different sites in and around mining residues in Sepetiba Bay, Brazil. We analyzed metal concentration, physical, chemical, and microbiological parameters related to prokaryotic diversity in low metal impacted compared to highly polluted environments with Zn at level of gram per liter and Cd-Pb at level of microgram per liter. Application of molecular methods for community structure analyses showed that Archaea and Bacteria groups present a phylogenetic relationship with uncultured environmental organisms. Phylogenetic analysis revealed that bacteria present at the five sites fell into seven known divisions, alpha-Proteobacteria (13.4%), beta-Proteobacteria (16.3%), gamma-Proteobacteria (4.3%), Sphingobacteriales (4.3%), Actinobacteria (3.2%) Acidobacteria (2.1%), Cyanobacteria (11.9%), and unclassified bacteria (44.5%). Almost all archaeal clones were related to uncultivated Crenarchaeota species, which were shared between high impacted and low impacted waters. Rarefaction curves showed that bacterial groups are more diverse than archaeal groups while the overall prokaryotic biodiversity is lower in high metal impacted environments than in less polluted habitats. Knowledge of this microbial community structure will help in understanding prokaryotic diversity, biogeography, and the role of microorganisms in zinc smelting AMD generation and perhaps it may be exploited for environmental remediation procedures in this area.

RNA-dependent conversion of phosphoserine forms selenocysteine in eukaryotes and archaea.

The trace element selenium is found in proteins as selenocysteine (Sec), the 21st amino acid to participate in ribosome-mediated translation. The substrate for ribosomal protein synthesis is selenocysteinyl-tRNA(Sec). Its biosynthesis from seryl-tRNA(Sec) has been established for bacteria, but the mechanism of conversion from Ser-tRNA(Sec) remained unresolved for archaea and eukarya. Here, we provide evidence for a different route present in these domains of life that requires the tRNA(Sec)-dependent conversion of O-phosphoserine (Sep) to Sec. In this two-step pathway, O-phosphoseryl-tRNA(Sec) kinase (PSTK) converts Ser-tRNA(Sec) to Sep-tRNA(Sec). This misacylated tRNA is the obligatory precursor for a Sep-tRNA:Sec-tRNA synthase (SepSecS); this protein was previously annotated as SLA/LP. The human and archaeal SepSecS genes complement in vivo an Escherichia coli Sec synthase (SelA) deletion strain. Furthermore, purified recombinant SepSecS converts Sep-tRNA(Sec) into Sec-tRNA(Sec) in vitro in the presence of sodium selenite and purified recombinant E. coli selenophosphate synthetase (SelD). Phylogenetic arguments suggest that Sec decoding was present in the last universal common ancestor. SepSecS and PSTK coevolved with the archaeal and eukaryotic lineages, but the history of PSTK is marked by several horizontal gene transfer events, including transfer to non-Sec-decoding Cyanobacteria and fungi.

A non-discriminating aspartyl-tRNA synthetase from Halobacterium salinarum.

The tRNA-dependent transamidation pathway is the essential route for Asn-tRNA(Asn) formation in organisms that lack an asparaginyl-tRNA synthetase. This pathway relies on a nondiscriminating aspartyl-tRNA synthetase (ND-AspRS encoded by aspS), an enzyme with relaxed tRNA specificity, to form Asp-tRNA(Asn). The misacylated tRNA is then converted to Asn-tRNA(Asn) by the action of an Asp-tRNA(Asn) amidotransferase. Here we show that Asn-tRNA(Asn) formation in the extreme halophile Halobacterium salinarum also occurs by this transamidation mechanism, and we explore the property of the haloarchaeal AspRS to aspartylate tRNA(Asn) in vivo and in vitro. Transformation of the E. coli trpA34 strain with the H. salinarum aspS and tRNA(Asn) genes led to restoration of tryptophan prototrophy by missense suppression of the trpA34 mutant with heterologously in vivo formed Asp-tRNA(Asn). The haloarchaeal AspRS works well at low and high (0.1-3 M) salt concentrations but it is unable to use Escherichia coli tRNA as substrate. We show that mutations of two amino acids (H26 and P84) located in the AspRS anticodon binding domain limit the specificity of this nondiscriminating enzyme towards tRNA(Asn). Thus, as was observed in an archaeal discriminating AspRS and a bacterial ND-AspRS, amino acids in these positions influence the enzyme's tRNA selection.

Expression and homology modeling of 2-aminobiphenyl-2,3-diol-1,2-dioxygenase from Pseudomonas stutzeri carbazole degradation pathway.

The enzyme 2'-aminobiphenyl-2,3-diol-1,2-dioxygenase (CarB), encoded by two genes (carBa and carBb), is an alpha(2)beta(2) heterotetramer that presents meta-cleavage activity toward the hydroxylated aromatic ring in the carbazole degradation pathway from petroleum-degrader bacteria Pseudomonas spp. The 1,082-base pair polymerase chain reaction product corresponding to carBaBb genes from Pseudomonas stutzeri ATCC 31258 was cloned by site-specific recombination and expressed in high levels in Escherichia coli BL21-SI with a histidine-tag and in native form. The CarB activity toward 2,3-dihydroxybiphenyl was similar for these two constructions. The alpha(2)beta(2)-heterotetrameric 3D model of CarB dioxygenase was proposed by homology modeling using the protocatechuate 4,5-dioxygenase (LigAB) structure as template. Accordingly, His12, His53, and Glu230 coordinate the Fe(II) in the catalytic site at the subunit CarBb. The model also indicates that His182 is the catalytic base responsible for deprotonating one of the hydroxyl group of the substrate by a hydrogen bond. The hydrophobic residues Trp257 and Phe258 in the CarB structure substituted the LigAB amino acid residues Ser269 and Asn270. These data could explain why the CarB was active for 2,3-dihydroxybiphenyl and not for protocatechuate.