Brazilian Journal of Microbiology最新文献

Xylitol is a highly demanded polyol in the food, pharmaceutical, and chemical industries. However, its current production methods are considered energy-intensive, require the use of hazardous chemical catalysts, and depend on complex and costly equipment. The biotechnological route of xylitol production is proposed as a sustainable alternative, but it still requires process improvements, such as enhanced fermentation capabilities, to be economically competitive. This study examined Candida tropicalis yeast to improve xylose-to-xylitol conversion via glucose: xylose ratio and pH modulation. Key parameters evaluated included xylose consumption rate (r_S), xylose-to-xylitol yield (Y_P/S), and xylitol volumetric productivity (Q_P). Conditions with 50 g/L xylose at pH 3.5 exhibited superior xylitol production: 29.81 g/L, Q_P of 0.52 g/L/h, and Y_P/S of 0.54 g/g at 48 h. The statistical model demonstrated that the maximum Y_P/S and Q_P values have not yet been achieved. This could present an opportunity to be explored through yeast genetic engineering approaches. Additionally, the quantitative expression of the xylose transporter genes (XUT1 and STL2) and the xylose reductase gene (XYL1), previously identified in C. tropicalis, was evaluated under all tested conditions. Upregulation of the XUT1 was correlated with higher xylose concentrations, while STL2 was favored at lower xylose concentrations. The expression of XYL1 showed upregulation over time with higher xylose ratios. The high transcription levels and expression profile suggest that Xut1p-mediated xylose transport occurs through a proton symport mechanism. The results indicate that the pH factor indirectly influences XUT1 gene transcription, possibly as a compensatory response to the reduced transporter efficiency under high pH conditions. The present work underscores the influence of glucose ratios and pH in xylitol production, as well as the gene expression of xylose transporters and the key enzyme xylose reductase. Leveraging these insights can significantly enhance xylitol production from hemicellulosic hydrolysates through biotechnological pathways.

Escherichia coli is a zoonotic bacterium, and its resistance to antimicrobials has become an increasing problem in global health. This study aimed to determine the phenotypic and genotypic pooled prevalence of E. coli with antimicrobial resistance profiles in poultry through systematic review and meta-analysis. Articles available in scientific databases from years 2017 to 2024 were evaluated. Overall, 18 studies were included in the meta-analysis and prevalence of E. coli resistance in poultry. Estimated by the random effects model, the pooled prevalence of resistance to at least one antibiotic in E. coli isolated from poultry samples was 76.96% (95% CI = 48.74-92.15%), and multidrug-resistant isolates of 89.44% (95% CI = 75.51-95.88%). The highest prevalence was to nalidixic acid (86.67%; 95% CI = 59.32-96.67%), followed by isolates resistant to tetracycline (79.33%; 95% CI = 62.86-89.69%). Tetracycline resistance genes had the highest prevalence, with 29.78% of isolates (498/1076) positive for at least one of the three genes (tetA, tetB and/or tetC). The levels of phenotypic and genotypic prevalence of E. coli in poultry can provide a scientific basis for the control of antibiotic-resistant strains and contribute to the competent authorities to guide the management interventions that best suit the different geographical regions.

Toxoplasmosis is a parasitic disease caused by infection with Toxoplasma gondii, capable of infecting a wide range of hosts. The parasite exhibits a broad genetic diversity, necessitating genotypic characterization for genotype identification and associations with epidemiological information. Therefore, the Restriction Fragment Length Polymorphism (RFLP) technique is used for characterization. This study aimed to perform genotypic characterization of isolates from pregnant women infected during a human toxoplasmosis outbreak, comparing the RFLP and Sanger Sequencing methodologies. For this purpose, six human isolates were subjected to conventional PCR, Multiplex PCR, Nested PCR, Enzymatic Digestion, and Sanger Sequencing. Additionally, the standard strains GTI (Type I), PTG (Type II), and CTG (Type III) were also subjected to the same techniques described above. Subsequently, the amplified DNA products were compared with the standard strains. As a result, it was observed that Sanger Sequencing provides the same information as RFLP PCR, as well as the possibility of cost reduction for genotypic characterization, and providing greater agility in issuing results. Additionally, Sanger Sequencing of T. gondii isolates allows for detailed evaluation of nucleotide sequences, including the assessment of SNPs and enzymatic restriction sites, which the RFLP technique does not.

It is well-established that the dam and seqA genes act in the biofilm production in Salmonella. However, the molecular basis underlying this activity remains unexplored. This study aims to address this gap in the literature. In this study, comparative Fourier Transform Infrared (FT-IR) Spectroscopy and Raman spectral analyses were conducted to investigate the molecular basis of decreases in swimming, swarming motility, and biofilm characteristics observed in the dam and seqA gene mutants of S. Typhimurium DMC4 wild-type strain. The comparative analysis revealed a pronounced reduction in proteins, lipids, carbohydrates, and nucleic acids within the biofilm structures of mutant strains. These findings confirm that these macromolecules are crucial for the integrity and functionality of biofilm structures. FT-IR analysis showed that while amide-I bands decreased in the biofilm structures of mutant strains, amide-II bands increased compared to the wild-type strain. Similarly, Raman analyses indicated an increase in amide-IV bonds and a decrease in amide-V bonds. The parallelism between FT-IR and Raman spectral analysis results, particularly regarding amide I, amide V, amide II, and amide IV bands, is noteworthy. Additionally, these findings may lead to the development of markers for rapidly diagnosing transitions from planktonic to biofilm form in Salmonella. The substantial decrease in β-glucans and lipids, including cellulose, within the biofilm matrix of mutant strains highlights the critical role these polymers play in swimming and swarming motility. Given the clinical and industrial importance of Salmonella biofilms, it is crucial to develop strategies to prevent biofilm formation and identify target molecules that can inhibit biofilm formation. The results of our study suggest that β-glucans and amides are essential targets in the effort to combat Salmonella biofilms.

In the post-rotavirus (RVA) vaccination era, uncommon and zoonotic strains have emerged as causative agents of acute gastroenteritis in humans, including the equine-like G3P[8] strains. First identified in 2013, this strain has quickly spread worldwide, reaching the position of the most prevalent genotype in many countries, including Brazil. Here, we report full genotype characterization and phylogenetic analysis of two equine-like G3P[8] strains detected in Goiás, a state in the Cerrado biome of the Brazilian Midwestern region, during the year of 2019. The strains were detected in different socioeconomic and demographic contexts: GO-MR from an asymptomatic adult living in a rural traditional community and GO-H5 from a symptomatic child from the state capital, with access to safe drinking water and essential sanitation services. These strains also displayed different backbone constellations considering the NSP2 gene segment (G3-P [8]-I2-R2-C2-M2-A2-N2-T2-E2-H2 for GO-MR and G3-P[8]-I2-R2-C2-M2-A2-N1-T2-E2-H2 for GO-H5). Furthermore, significant mutations in the main epitope sites of the VP7 and VP8* proteins of the detected strains, and other Brazilian G3P[8] viruses, were found with the comparison to RV1 and RV5 vaccine proteins, indicating a potential ability of these viruses to evade vaccine protection, which may contribute to their prevalence both nationally and globally. In summary, this study corroborates the genetic diversity of equine-like G3P[8] DS-1-like strains circulating worldwide, highlights the epidemiological importance of adults as reservoirs of RVA and shows the substantial differences between these emerging strains and the currently used anti-RVA vaccines, which may partially explain their predominance due to potential evasion of vaccine-induced protection.

Candida albicans comprises over 80% of isolates from all forms of human candidiasis. Biofilm formation enhances their capacity to withstand therapeutic treatments. In addition to providing protection, biofilm formation by C. albicans enhances its pathogenicity. Understanding the fundamental mechanisms underlying biofilm formation is crucial to advance our understanding and treatment of invasive Candida infections. An initial screening of 57 Candida spp. isolates using CHROMagar Candida (CHROMagar) media revealed that 46 were C. albicans. Of these, 12 isolates (33.3%) had the capacity to form biofilms. These 12 isolates were subjected to multiple biochemical and physiological tests, as well as 18 S rRNA sequencing, to confirm the presence of C. albicans. Upon analysis of their sensitivity to conventional antifungal agents, the isolates showed varying resistance to terbinafine (91.6%), voriconazole (50%), and fluconazole (42%). Among these, only CD50 showed resistance to all antifungal agents. Isolate CD50 also showed the presence of major biofilm-specific genes such as ALS3, EFG1, and BCR1, as confirmed by PCR. Exposure of CD50 to gentamicin-miconazole, a commonly prescribed drug combination to treat skin infections, resulted in elevated levels of gene expression, with ALS3 showing the highest fold increase. These observations highlight the necessity of understanding the proteins involved in biofilm formation and designing ligands with potential antifungal efficacy.

Widely produced and marketed worldwide, orchids suffers from several diseases that have a negative effect on production. Black rot disease is among the most common and severe disease, characterized by black spots of rot on leaves, pseudobulbs and roots, which usually lead to the plant death. The world literature lists some Phytophthora species as causal agents of the disease, but there is no advanced study on the etiology of this disease in Brazil, which makes it difficult to determine an efficient control method. This work aims to contribute to the study of the etiology of black rot on Cattleya leopoldii in Brazil. Severely diseased C. leopoldii plants with typical symptoms of black rot, collected from a commercial orchid farm in Brazil, were taken to the laboratory and used to isolate the pathogen. Based on morphological characters analysis combined with molecular data, the isolates were identified as belonging to the species Phytophthora heterospora. This is the first worldwide report of P. heterospora causing black rot disease on orchids.

In this study water samples were investigated for the presence of heavy metals and pesticide resistance in Escherichia coli (E. coli) collected from district Jhal Magsi. Identification of E. coli was carried out via Polymerase Chain Reaction (PCR) assays. Heavy metals and pesticide resistance were conducted by the Kirby-Bauer disk diffusion method. E. coli was confirmed by using uidA (623 bp) and usp (515 bp) genes primer. A relatively high resistance rate was observed for Cd and DDT (2, 4 D) with 100% at the concentration of 1600 µl/mL. Samples showed the resistance pattern for Cr with 55% and sensitivity was 45% at 800 µl/mL. Resistance and sensitive percentage of Pb, Co were observed 61, 63, and 39, 37% at 400 µl/mL. Cyanazine resistance and the sensitive percentage were 51 and 49% at 800 µg/mL. For Chlorpyrifos and Carbofuran, 54 and 65% resistance and sensitivity 46 and 35% were measured at a lower range of 400 µl/mL. Excessive use of heavy metals and pesticide pollution in standing water near agriculture fields contributed to accelerating the abundance of multi-pollutant-resistant E. coli in water that could be useful in the bioremediation of pesticides and heavy metals.

Salmonella Heidelberg, a serotype commonly found in Southern Brazil, is characterized by its high resistance and persistence in the poultry production. This study aimed to characterize the antimicrobial resistance of S. Heidelberg strains. In total, 100 strains isolated from poultry between 2020 and 2022 were evaluated. Phenotypic analyses were performed to determine the susceptibility of 16 antimicrobial agents and detect extended-spectrum beta-lactamase (ESBL)-producing strains. Molecular analyses were performed to detect 11 antimicrobial resistance genes (using polymerase chain reaction [PCR]) and integron class 1 genes (using real-time PCR). A total of 98% of isolates was classified as multidrug-resistant. All isolates were resistant to penicillin and lincomycin. High resistance rates (> 85%) were observed for tetracycline, doxycycline, cephalexin, amoxicillin, and ceftiofur. A significant increase (p < 0.05) in antimicrobial resistance is observed for amoxicillin, cephalexin, and ceftiofur between 2020 and 2022. No significant differences (p > 0.05) were observed in antimicrobial resistance with respect to the region of isolation, season, or company. In total, 25% of isolates were ESBL producers. Integron class 1 gene was detected in only one strain, whereas sul2 was detected in 99%, tet(A) in 66%, bla_TEM in 37%, strB in 17%, cmlA in 15%, and tet(B) in 11% of the strains. Other genes were not detected or were detected in < 2% of the strains. The results showed a high overall resistance, which increased over the evaluated period. The high proportions of ESBL-producing and antimicrobial resistant strains represent a risk for highly-resistant S. Heidelberg dissemination across broiler flocks.