Brazilian Journal of Microbiology最新文献

Pseudomonas sp. AU10 is an Antarctic psychrotolerant bacterium that produces a dye-decolorizing peroxidase (DyP-AU10). The recombinant enzyme (rDyP-AU10) is a heme-peroxidase that decolors dyes and modifies kraft lignin. In this work, we report the best activity parameters for lignin modification (at 45 °C and pH 4) and show that the enzyme increases the number of aldehydes, ketones, and phenolic compounds. The analyses of the HPLC profile of samples also support that rDyP-AU10 induces the chemical change of kraft lignin. The enzyme also acts as a biobleaching agent on cellulose pulps, as shown by the reduction in kappa number. We also included experiments with a commercial laccase from Trametes versicolor and performed experiments using single enzymes and, in combination. The results show that rDyP-AU10 and the commercial laccase do not have a synergic activity as a modifying system, on cellulose pulp as substrates. However, results suggest that rDyP-AU10 holds potential as a member of the portfolio of lignin-modifying enzymes.

Developing an effective vaccine for haemorrhagic septicaemia (HS) in cattle and buffaloes is urgently needed. While preferred for their safety, achieving sufficient, cross-protective, and long-lasting immunity is still challenging when administering inactivated vaccines. This study aimed to assess the efficacy of four inactivating components comprising three inactivating agents: (1) Binary ethylenimine (BEI), (2) Formalin, (3) a combination of BEI and Formalin, and (4) Hydrogen peroxide (H₂O₂), in inactivating Pasteurella multocida to enhance HS vaccine potency. H₂O₂ demonstrated the fastest inactivation kinetics, killing Pasteurella multocida within a few minutes. The combination of BEI and Formalin showed relatively rapid inactivation compared to Formalin or BEI alone. BEI, known for targeting nucleic acids with minimal impact on protein integrity, showed promise but required higher concentrations (8 mM) and a longer duration (16 h) for complete inactivation. Based on the inactivation kinetics, 8 mM BEI, 0.1% Formalin, 8 mM BEI + 0.1% Formalin, and 1% H₂O₂ were chosen for the experimental vaccine formulations. The inactivated Pasteurella multocida were adjuvanted with Montanide ISA-201 oil adjuvant and evaluated in mice model. All vaccine formulations elicited protective responses of over 6.5 log₁₀ units, indicating the high potency of the vaccine formulations. Notably, the vaccine prepared with an H₂O₂ inactivating agent elicited protection of > 8 log₁₀ units. Our study concludes that H₂O₂, with its rapid inactivation kinetics and safety profile, presents a promising alternative inactivating agent for HS vaccine development. Future studies should evaluate the protective efficacy of H₂O₂-inactivated vaccines in target animals.

Diabetes is a critical worldwide health problem. Numerous studies have focused on producing recombinant human insulin to address this issue. In this research, the process factors of production of recombinant His-tagged proinsulin in E. coli BL21 (DE3) strain were studied. Bacterial culture factors with significant effects on the amount of produced recombinant proinsulin were screened using a Taguchi L8 orthogonal array. Proinsulin expression was conducted under predicted optimal conditions. The folded impure His-tagged proinsulin was purified using immobilized metal ion affinity chromatography (IMAC). A novel IMAC sequence order combined with the use of non-His-tagged C-peptide cleavage enzymes followed by His- tagged enterokinase enzyme enabled simultaneous protein purification and elimination of C-peptide and His-tag in just one step. Statistical analysis revealed that the amount of produced proinsulin was significantly affected by several factors including the post-induction incubation temperature, Isopropyl ß-D-1-thiogalactopyranoside (IPTG) concentration, pre-induction incubation temperature, the glucose concentration, bacterial cell population at induction step, and the time of harvesting. The optimized model resulted in an empirical maximum proinsulin concentration of 254.5 ± 11.7 µg/ml. The high purity of the purified insulin (> 96% by SDS-PAGE) indicated that applied IMAC sequence order could be considered an efficient technique for on-column cleavage and insulin purification.

Cowpea (Vigna unguiculata) is recognized as a promiscuous legume in its symbiotic relationships with rhizobia, capable of forming associations with a wide range of bacterial species. Our study focused on assessing the diversity of bacterial strains present in cowpea nodules when inoculated with soils from six indigenous lands of Mato Grosso do Sul state, Central-Western Brazil, comprising the Cerrado and the Pantanal biomes, which are known for their rich diversity. The DNA profiles (BOX-PCR) of 89 strains indicated great genetic diversity, with 20 groups and 23 strains occupying single positions, and all strains grouped at a final similarity level of only 25%. Further characterization using 16S rRNA gene sequencing revealed a diverse array of bacterial genera associated with the cowpea nodules. The strains (number in parenthesis) were classified into ten genera: Agrobacterium (47), Ancylobacter (2), Burkholderia (12), Ensifer (1), Enterobacter (1), Mesorhizobium (1), Microbacterium (1), Paraburkholderia (1), Rhizobium (22), and Stenotrophomonas (1), split into four different classes. Notably, only Ensifer, Mesorhizobium, Rhizobium, and Paraburkholderia are classified as rhizobia. Phylogenetic analysis was conducted based on the classes of the identified genera and the type strains of the closest species. Our integrated analyses, combining phenotypic, genotypic, and phylogenetic approaches, highlighted the significant promiscuity of cowpea in associating with a diverse array of bacteria within nodules, showcasing the Brazilian soils as a hotspot of bacterial diversity.

Aeromonas inhabit diverse aquatic habitats and are recognized as both opportunistic and primary pathogens of fish and humans. This study delineates the biochemical and gyrB sequence-based molecular identification of 14 Aeromonas strains isolated from aquatic environments in Kerala, India, identifying them as A. dhakensis (50%), A. hydrophila (28.6%), and A. jandaei (21.4%). These strains exhibit a high prevalence of virulence genes (act, flaA, ser, gcat, lip, and ela) implicated in pathogenesis in both fish and humans. These findings underline the emergence of A. dhakensis, often misidentified as A. hydrophila, as a potential pathogen, highlighting the necessity for comprehensive identification methods. Significantly, all strains demonstrated beta-hemolysis and moderate to strong biofilm formation, enhancing their infectivity potential. Moreover, all isolates exhibited multidrug resistance, with a multiple antimicrobial resistance (MAR) index ranging from 0.39 to 0.56, and a significant presence of class 1 (500-1100 bp) and class 2 (250-700 bp) integrons, indicating their potential risk to both fish and human populations. Our results underscore the role of aquatic environment as a repository for virulent and multidrug-resistant Aeromonas spp., emphasizing the imperative for prudent antimicrobial usage and regular monitoring of antimicrobial resistance (AMR) in these environments.

Pesticides play a major role in the current scenario of Indian agriculture. Agriculture is a backbone of the country's economy contributing to 54% of employment. Being a vastly populated country, food aid dependency rate is very high. To meet the requirements of such a huge supply, high crop yields are necessary to sustain the food security. Thus, an abundance use of pesticides is quite common, ranking among the top producers of pesticide in the world. Organophosphates (OPP) being one of the major pesticides used in India. Known for causing acute toxicity, organophosphate pesticides are needed to be used controllably, and residues released into the environment should be treated to render them harmless. Biological degradation is one of the most effective ways to achieve that. However, exploring potential candidate for the purpose is still not sufficient compared to the necessity to alleviate organophosphates from the environment. This study examines the microbial degradation of dimethoate, an organophosphate pesticide, using Bacillus paramycoides. These bacteria were isolated from the rhizospheric soil of sugarcane fields in Sevur, Tamil Nadu, India, which has been exposed to dimethoate for over 10 years. The strain has been extensively studied to check its prospect for environmental stress, pesticide tolerance, and degradation efficiency. Degradation of dimethoate was detected by Fourier transform infra-red spectroscopy (FTIR) analysis. The isolate was found to degrade dimethoate by 97.6% in 5 days with a tolerance of 1000ppm for the targeted pesticide. Emphasis have also been placed on detecting the secondary metabolites produced by the isolate using gas chromatography-Mass spectrometry(GC-MS) analysis, in which, a compound Phosphorothioic O, O,S-acid, a probable by-product of dimethoate degradation was identified. Significant other biologically important metabolites obtained from B.paramycoides, have also been reported in this study, which are known to have different anticancerous and antibacterial properties.

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.

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.

This study evaluated the stability of novel nutraceuticals containing jabuticaba freeze-dried peel (FJP) and a mix of potential probiotic L. fermentum strains [139, 263 and 296 (LfM)] (JM: FJP + LfM; JFM: FJB + LfM + fructooligosaccharides) through determination of thermal stability, viable cell counts, bacterial physiological status, phenolic compound contents, and antioxidant activity during 90 days of storage (11% relative humidity, 4 and 25 ºC). JM and JFM were thermally stable, with satisfactory stability in temperature variations. JFM had higher L. fermentum viable cell counts than JM during storage. However, the physiological status of L. fermentum cells in JM and JFM indicated maintenance of vitality and functionality rather than death, regardless of the storage temperature. JM and JFM had a high content of phenolic acids and anthocyanins and antioxidant activity during storage. JFM stored under refrigeration had the most outstanding stability and potential functionality regarding the high viable probiotic cell counts, phenolic compound content, and antioxidant activity.

The coronavirus disease-2019 (COVID-19) pandemic has affected different sectors of society, and healthcare workers have been particularly impacted. This study aimed to describe the clinical, epidemiological, and molecular characteristics of SARS-CoV-2 infections among healthcare workers in Evandro Chagas Institute, a research reference center in Brazil, from October 2020 to July 2022. 845 samples were collected from individuals who presented clinical symptoms of respiratory infection. Nasopharyngeal positive samples were submitted through genome sequencing. Clinical, epidemiological, and the SARS-CoV-2 lineages (or variants) were analyzed. SARS-CoV-2 positivity was detected in 31.8% (269/845) of samples with a higher prevalence of females (60.2%). The highest SARS-CoV-2 positivity rates were reported in March 2021 (39%), January 2022 (65%), and July 2022 (56%). On clinical symptoms, arthralgia, chills, and diarrhea were statistically significantly detected in 2020; fever, runny nose, and arthralgia in 2021; runny nose, and cough in 2022. On molecular analysis of SARS-CoV-2, 66 samples (25.3%, 66/269) were sequenced and the most prevalent lineage was the Omicron, representing 57.6%. Studies on the epidemiological and clinical characteristics of HCW are essential to propose control measures and work management since research centers play a major role in surveillance to identify and monitor infectious diseases.