Brazilian Journal of Microbiology最新文献

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the leading causes of infection worldwide due to its antimicrobial resistance. Plant-derived essential oils (EOs) have undergone extensive observational and clinical research to explore their antimicrobial properties. The present study aimed to check mec A positive MRSA isolates using sequencing analysis, determination of chemical composition using gas chromatography-mass spectroscopy (GC-MS), antioxidant, and antimicrobial activity of Anethum graveolens and Piper betle EOs against the infectious agent MRSA. The result demonstrates a significant antibacterial activity of both essential oils against MRSA clinical isolates. GC-MS analysis of Piper betle showed (41.06%) 3-Allyl-6-methoxyphenol (Eugenol) as the major compound, whereas Anethum graveolens exhibited o-cymene (14.01%) abundantly. Piper betle essential oil retained appreciable levels of total phenolic (39.5 ± 10.9 mg/g of gallic acid equivalents) and flavonoid content (216 ± 145 mg quercetin equivalent/g), when compared to Anethum graveolens essential oil. A strong correlation was observed between antioxidant activity (DPPH, FRAP, and ABTS), total phenolic, and total flavonoid content in the Piper betle and displayed using principal component analysis (PCA) and a scatter matrix plot. Parallelly, clear morphological bacterial alterations were visualized by scanning electron microscopy after treating it with essential oils. MRSA showed malformed cell surfaces or broken cells with pore formation and septae. These findings imply that both essential oils are potential natural sources of antimicrobials against the MRSA superbug. They can also be used in combination therapies with other plant EOs or with traditional antibiotics to combat the rise of bacteria resistance.

Proteases are hydrolases that act on peptide bonds, releasing amino acids and/or oligopeptides, and are involved in essential functions in all organisms. They represent an important segment of the global enzyme market, with applications in the food, leather, detergent, and pharmaceutical industries. Depending on their industrial use, proteases should exhibit high activity under extreme conditions, such as low temperatures, e.g. cold-active protease may have potential uses in the detergent industry. Cold-active enzymes show high catalytic constants (k_cat) at low temperatures and thermolability, allowing their inactivation at moderate temperatures. This work aimed to characterize an extracellular proteolytic extract produced by an Antarctic isolate identified as Flavobacterium sp. strain AU13, and to evaluate its biotechnological potential as a detergent additive. By mass spectrometry analysis, we identified a major 50 kDa protease, with high identity with an epralysin from Pseudomonas fluorescens Pf0-1, an alkaline extracellular metalloprotease belonging to the serralysin subfamily. The AU13 proteolytic extract showed metalloprotease activity and, maximal activity over a wide pH range (pH 5 to 8); it also showed maximal activity at 40 °C, suggesting that this extracellular protease is a cold-active enzyme. The AU13 proteolytic extract demonstrated stable and compatible activity with surfactants and oxidants, making it a promising additive for commercial laundry detergents. Its ability to function effectively in cold-water washing conditions offers a significant advantage over conventional enzymes, potentially improving energy efficiency in industrial processes. The biochemical properties and performance of the AU13 proteolytic extract in the presence of laundry detergents, suggest that AU13 produces an extracellular protease with a biotechnological potential.

Adjuvants are crucial for maintaining specific, protective, and long-lasting immunity. Here, we aimed to evaluate the antigenic and immunogenic activity of a recombinant form of the S1 domain of the Spike protein, associated with biogenic silver nanoparticles (bio-AgNP) and Alhydrogel^® as an alternative and conventional adjuvant, respectively, for a SARS-CoV-2 subunit vaccine. We produced and evaluated the antigenicity of the recombinant S1 (rS1) protein by testing its recognition by antibodies present in SARS-CoV-2 positive human serum. The immunogenicity of the rS1 protein was assessed in vivo by its ability to induce antibody production in mice. Furthermore, we sought to establish the types of humoral and cellular immune responses generated through intramuscular immunization in BALB/c mice with the rS1 + bio-AgNP vaccine. The recombinant S1 (rS1) protein was successfully cloned, expressed in Escherichia coli, and confirmed to have strong antigenic potential, being recognized by human antibodies up to a 1:51,200 serum dilution. In vivo assays showed that vaccines using rS1 with either bio-AgNP or Alhydrogel^® as adjuvants induced high and consistent antibody titers (1:51,200) and a range of antibody isotypes in mice. Cellular immune response analysis revealed significant IL-10 expression with rS1 + bio-AgNP and both IL-10 and TNFα expression with rS1 + Alhydrogel^®. These results support rS1 + bio-AgNP as a promising vaccine candidate for future development, highlighting its potential not only as a viable alternative to traditional adjuvants but also as an innovative contribution to advancing more effective and accessible immunological strategies.

The influence of arbuscular mycorrhizal fungi (AMF) inoculation on the growth and physiology of Phaseolus vulgaris L. and Zea mays L. in the Brazilian tropical seasonal dry forest is not well known. We examined the effects of indigenous AMF species inoculation on these two annual crops at phosphorus-deficient soils under glasshouse conditions. The AMF species used as inoculum were collected from the root zone of Mimosa tenuiflora, a native plant of the Caatinga ecoregion. The inoculum was propagated in plastic pots with Trifolium sp. as the host plant. We investigated the effect of four treatments: (1) Control- non-inoculated; (2) Acaulospora inoculum- inoculation with A. tuberculata; (3) Gigaspora inoculum- inoculation with G. gigantea; and (4) Mixed inoculum- inoculation with both Acaulospora and Gigaspora species. We found that inoculation with the indigenous AMF community enhanced plant dry biomass, plant P concentration, root colonization, and physiological responses for both model plants. This study highlighted the importance of exploring the P molecule as an integral element in plant development and presents the AMF inoculation as an efficient alternative to overcome low-P conditions, leading to improved nutrient acquisition in low-fertility soils, better growth conditions through enhanced physiological responses, and ultimately increased plant dry biomass.

Plant parts such as roots, bark, leaves, flowers, and fruits that hold ethnopharmacological significance are naturally prone to microbial contamination, influenced by environmental factors like moisture and humidity. This study focuses on assessing the microbial load in the raw material of Tribulus terrestris (TT). The primary bacterium isolated from the pulverized raw material was identified as Bacillus haynesii through 16S rRNA sequencing. Biochemical assays revealed the organism's ability to utilize lysine and ornithine, produce urease, and generate hydrogen sulfide. The bacterium exhibited resistance to multiple antibiotics and caused 21.5% hemolysis in RBC lysis assays. To reduce microbial contamination, Glutaraldehyde (GA) and polyhexamethylene biguanide (PHMB) were tested, with GA at 1% reducing the microbial load by 99% without affecting the yield (0.5%) or bioactive saponin content. High-Performance Liquid Chromatography (HPLC) confirmed the absence of residual GA, ensuring an eco-friendly and safe process. This highlights the importance of quality control measures, including Hazard Analysis and Critical Control Points (HACCP) regulations, in maintaining the integrity of herbal extracts.

The objective of this work was to investigate the biofilm production capacity of the isolate EB-40 (Bacillus cereus) in a culture medium for the multiplication of microorganisms and in roots of in vitro grown banana explants. It was observed that the isolate was able to produce biofilms in tryptone, soy and agar (TSA) culture medium and in the roots of explants. The format, architecture and location of the biofilms in TSA culture medium presented an exopolymer matrix formed by EB-40 presented coccoid bacillary cells and fibrillar structures. In roots explants was verified the formation of microcolonies adhered to the root hairs. The information obtained in this experiment allowed inferring the ability of the isolate to produce biofilms and the colonization pattern shown when associated with banana tree roots.

Endophytic actinomycetes are potential sources of novel pharmaceutically active metabolites, significantly advancing natural product research. In the present investigation, secondary metabolites from two endophytic actinomycetes, Streptomyces parvulus GloL3, and Streptomyces lienomycini SK5, isolated from medicinal plant taxa, Globba marantina, and Selaginella kraussiana, exhibited broad-spectrum bioactivity. Ethyl Acetate (EA) extract of SK5 showed antimicrobial activity against nine human pathogens, including Methicillin-resistant Staphylococcus aureus (MRSA), Candida tropicalis, and C. albicans, with a minimum microbicidal concentration (MMC) of 50-300 µg mL^-1. It healed the MRSA-mediated wounds in Swiss albino mice in vivo. EA extracts dissociate the pathogenic cell membranes and cause leakage of biomacromolecules-nucleic acid, protein, and potassium ions. Also, critical housekeeping enzymes involved in the cellular respiratory mechanisms of the pathogens were blocked. GloL3 has antioxidative potentialities against DPPH, ABTS, FRAP, and H₂O₂ free radical generators with an IC₅₀ value of 21.18 ± 0.33, 43.58 ± 0.91, 88.24 ± 1.24, and 111.03 ± 6.42 µg mL^-1. It improves the enzymatic antioxidant parameters in treated peritoneal macrophage cells of Swiss albino mice. Constituents of the EA extracts of GloL3 and SK5 are bactobolin, actinobolin, 5-(2-aminoethyl)-1 H imidazole-2-carbaldehyde, isovaleric acid, fulvic acid, phenol, 4-[2-(methylamino) ethyl]-, eicosanoic acid, heptadecanoic acid, etc. The present findings suggest that metabolites from the endophytes of medicinal plants hold potent pharmaceutical utilities.

Slaughterhouses produce huge volumes of effluents throughout the production chain that, when discharged untreated into bodies of water, can become a source of environmental contamination. This is particularly worrisome if these effluents are used for irrigation since they increase contamination levels and spread pathogens and resistance determinants to humans and animals. Therefore, in this study, we assessed antimicrobial resistance in bacteria isolated from inlet water, equalization wastewater tanks, treatment plant wastewater, and treated wastewater in slaughterhouse facilities in Rio de Janeiro, Brazil. Four samples were collected at each of the collection points, between June 2021 and July 2022. Following bacterial isolation and identification, the samples were analyzed for antimicrobial resistance using the disk diffusion method to test aminoglycoside, beta-lactam, and fluoroquinolone antimicrobials. A total of 229 bacteria were isolated, with 74 isolates selected from the genera Citrobacter (12), Enterobacter (14), Klebsiella (35), Serratia (5), and Pseudomonas (8). Inlet water had the lowest number of isolates and was the only point with gentamicin-resistant isolates. Raw effluent from the equalization tank showed the highest number of isolated bacteria and resistance levels, followed by treated wastewater and the treatment plant. Across all samples, a high rate of cefoxitin-resistance was observed among the isolated bacteria. Klebsiella pneumoniae stood out as the species that demonstrated the greatest resistance to a variety of antimicrobials. These results highlight the importance of water quality monitoring in mitigating public health and environmental risks and high antimicrobial resistance levels.

Human Pegivirus Type 1 (HPgV-1), a ubiquitous commensal virus, has been recently suggested as a marker of immunologic function. There is scarce data for the presence, genotypes, and molecular characteristics of HPgV-1 among kidney transplant recipients. Therefore, the objective of this study was to examine the prevalence and the molecular characteristics (cycle threshold, genotypes) of this viral infection among kidney transplant recipients from the Brasília, Federal District of Brazil. HPgV-1 RNA detection in the plasma was assessed by RT-qPCR. Positive samples were submitted to sequencing and phylogenetic analysis of the 5´-UTR portion of the viral genome. The estimated HPgV-1 prevalence among renal-transplant recipients was 20%. The performed phylogenetic inference revealed that the most frequent genotype among these patients was HPgV-1 genotype 2 (78.9%) presented by its two subgenotypes (2 A and 2B), followed by genotypes 1 and 3 (10.5% each). This study presents new data about the HPgV-1 circulation and molecular characteristics among kidney transplant recipients from the Federal District of Brazil. Further work is fundamental to examine the effect of HPgV-1 among patients with immunological suppression, including kidney transplant recipients.

Enterococci are ubiquitous usually commensal bacteria that can act as opportunistic pathogens frequently associated with resistance to multiple antimicrobial classes. A variety of animals may carry potentially harmful enterococci. In the present work, the occurrence and characteristics of enterococci recovered from the fecal microbiota of wild birds belonging to four families (Accipitridae, Cathartidae, Falconidae and Strigidae) were investigated. Enterococci were recovered from 104 (92.0%) fecal samples obtained from 113 birds, and 260 strains were selected for additional characterization. Enterococcus faecalis was the predominant species (63.8%), followed by Enterococcus hirae (16.2%), Enterococcus faecium (11.5%), Enterococcus gallinarum (5.4%), Enterococcus avium (1.5%), Enterococcus casseliflavus (0.8%), and Enterococcus raffinosus and Enterococcus cecorum (0.4% each). Major percentages (11.9% 75.0%) of nonsusceptibility were observed to quinolones (particularly to enrofloxacin), erythromycin, rifampin, nitrofurantoin, tetracycline and streptomycin. Gentamicin and ampicillin resistances (13.3% each) were only detected among E. faecium. A total of 133 (51.2%) strains were MDR, showing a large variety of MDR profiles, composed by simultaneous resistance encompassing 3 to 12 antimicrobials. MDR strains were found in 68.2% of the birds. Antimicrobial resistance was associated with the presence of the aac(6')-aph(2″)-Ia, aph(2″)-Id, ant(6)-Ia, ant(9)-Ia, ant(9)-Ib, tet(M), tet(L), tet(S), erm(B), mef(A/E), msrC, and vat(D) genes. The most common virulence genes were efaA, gelE, ace, eeP, and asa1. PFGE analysis revealed a large genetic diversity among most of the strains. MLST performed for 35 E. faecalis strains revealed 23 different STs, whereas 14 STs were found among 18 E. faecium strains. Hospital-associated lineages ST22, ST25, ST56, ST1274 were identified. The results show that the wild birds investigated can carry a diversity of potentially hazardous enterococcal strains displaying multiple antimicrobial resistance and virulence genes, reinforcing the assumption that these animals provide an important target to monitor the circulation of microorganisms that deserve consideration under the One Health perspective.