Brazilian Journal of Microbiology最新文献

The phytopathogenic oomycete Phytopythium helicoides, previously known as Pythium helicoides, has emerged as a new threat to the Shatangju citrus cultivar (Citrus reticulata cv. Shatangju; '' in Chinese) in southern China. To enable rapid diagnosis and control of the leaf blight and stem rot caused by P. helicoides, we developed a visualized loop-mediated isothermal amplification (LAMP) assay targeting the β-tubulin gene of the pathogen. Using a carefully selected set of primers and optimized reaction conditions at 60 °C for 60 min, the LAMP assay can specifically detect the pathogen among various citrus-associated phytopathogens. The assay demonstrated high sensitivity, detecting as little as 30 pg of the pathogen DNA, comparable to the sensitivity of quantitative polymerase chain reaction (qPCR). We validated the practical application of this LAMP assay for diagnosing infections in citrus leaves and strawberry crowns. This newly developed LAMP assay offers a specific, sensitive, and rapid detection tool for P. helicoides, aiding in the control of Shatangju citrus leaf blight and stem rot, as well as other related crop diseases like strawberry crown rot.

Some natural products have been found to have a positive effect on the treatment of Type 2 Diabetes Mellitus (T2DM). The effective mechanism by which these natural products work may be attributed to their ability to alter the gut microbiome. In this study, considering the beneficial properties of resveratrol for T2DM, the mechanism of resveratrol in releasing of T2DM, the correlation between the apparent traits of resveratrol in T2DM mice and the changes in intestinal flora structure were explored. The intervention of resveratrol in different dose did effectively improve the apparent T2DM symptoms in mice, including reduced fasting blood glucose, enhance to both the insulin tolerance and glucose tolerance. Simultaneously, resveratrol can effectively ameliorate the pathological condition of the colon and rectum in T2DM mice, leading to a reduction in intestinal villi swelling and fat vacuoles. The intervention of resveratrol led to changes in the gut flora structure of T2DM mice. Erysipelas and Ileibacterium are crucial taxa of resveratrol involved in maintaining the balance of the gut microbiota. The abundance of Erysipelotrichaceae and Ileibacterium was significantly elevated under the treatment of resveratrol, and the compose of the gut microbiota was more inclined to healthy mice. T2DM symptoms could be alleviated by resveratrol through different mechanisms compared to metformin intervention.

Respiratory tract infection (RTI) is the most important cause of visiting both public and private medical care services. During the decade preceding Covid-19, in developing countries, there was a gap in the epidemiology of respiratory viral infections, probably due to the difficulty of detecting viral agents in clinical microbiology laboratories routine, at that time. In this context, the aim of this study was to describe the occurrence of virus, demographic factors associated and the likelihood of coinfections detection by multiplex PCR methods. The target also was to determine the involvement of respiratory viruses other than SARS-CoV-2 as agents of upper respiratory tract infections (URTIs) using rapid respiratory panels by multiplex real time PCR with flow chip methodology. Samples of SARSs patients, 530 in total, were tested between 2022 and 2023, obtained from nasopharyngeal swabs, nasopharyngeal exudates or nasopharyngeal aspirates. Of 530 tests, 30% was human rhinovirus, the most prevalent, followed by respiratory syncytial virus B (21.5%) and human adenovirus (17.4%). Among the total of positive samples, 83.8% belonged to patients aged between 0 and 10 years, 62.6% of whom were aged between 1 and 10 years. Multiple virus detection was found in 50.4% of the samples tested, 93.1% of which were from patients under the age of 18. Viral co-infection was evident in the finding and was higher (88.7%) in patients under the age of 18 yeas.

Culture-dependent and -independent studies have provided access to symbiont genes and the functions they play for host sponges. Thus, this work investigates the diversity, presence of genes of pharmacological interest, biological activities and metabolome of the bacteria isolated from the sponges Aplysina caissara and Aplysina fulva collected on the southwestern Atlantic Coast. The genes for Polyketide Synthases types I and II and Nonribosomal Peptide Synthetases were screened in more than 200 bacterial strains obtained, from which around 40% were putatively novel. Twenty-two were positive for at least one of the genes screened. Among them, 12 exhibited antimicrobial activities and one inhibited the proliferation of cancer cells. The metabolic profiles of the 22 strains were analyzed by liquid chromatography with tandem mass spectrometry and molecular network. The Global Natural Products Social Molecular Networking MolNetEnhancer workflow provided a more comprehensive understanding of the metabolic profiles. The results revealed the existence of a wide range of metabolites, however more than half of the compounds could not be identified. It was further observed that the metabolic diversity among the strains varied primarily due to the cultivation medium used. Together the results obtained here revealed the pharmacological potential of the bacteria isolated from Aplysina species.

Parasitoid wasps act as natural biological control agents for several harmful insect species. However, there is a lack of information regarding the exogenous RNA viruses that infect parasitoids and may contribute to the success of their parasitism strategies. This study aimed to investigate the presence, abundance, and replication of known exogenous viruses in two parasitoid wasp species and their corresponding preys. Utilizing publicly available RNA deep-sequencing data, two previously validated viruses from the parasitoid Tetrastichus brontispae were assessed in the target beetles Brontispa longissima and Octodonta nipae from the same geographic region. This study revealed the presence of the iflavirus TbRV-3 in both T. brontispae and O. nipae-derived samples, suggesting a potential exchange of the virus between the parasitoid and its host. In addition, there is substantial evidence that the Halyomorpha halys virus infects the parasitoid Telenomus podisi. Thus, this study proposes a close evolutionary relationship between the HhV strain identified in the parasitoid Telenomus podisi and the original strain detected in the prey H. halys. The viral association between trophically related species, such as parasitoids and their hosts, is demonstrated using features such as abundance and the presence of double-stranded RNA, which serves as a proxy for virus replication. Therefore, RNA viruses may coexist at both trophic levels, conferring an evolutionary advantage to the parasitism strategy.

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.

The success of biological nitrogen fixation (BNF) in soybean depends on two crucial factors, viz., seed inoculation and soil nutritional balance. The macronutrient sulfur (S) is vital to the formation of ferredoxin, a common source of electrons that controls the proper functioning of the subunits of the enzyme nitrogenase, responsible for the conversion of atmospheric nitrogen (N₂) to ammonia (NH₃⁺). However, as the S dynamics is a complex process in soil, it may cause to the plants to be sulfur limited. This study aims at assessing the relationship between S fertilization through the use of elemental-S, and bacterial inoculation (Bradyrhizobium spp.) and co-inoculation (Bradyrhizobium spp. and Azospirillum brasilense) on nodulation, production and quality of soybean. The study was performed on the 2017/2018 and 2018/2019 crop seasons, involving four experiments where two were carried out in Santa Maria and two in Augusto Pestana, Rio Grande do Sul, Brazil. Adopting the randomized experimental block design, the treatments included a 3 × 4 factorial design, with three inoculations (Non-inoculated control, Inoculation and Co-inoculation) together with four doses of S (0, 20, 40 and 60 kg ha^- 1). Evaluations were done of the plant nodulation, accumulation of shoot dry matter, yield constituents, and quality of the soybean grain. S fertilization and co-inoculation promote an increase in plant nodulation, proving to be an important strategy to support nitrogen supply to soybean crops. The application of elemental sulfur in doses between 20 and 40 kg ha^- 1 promotes nodulation, the accumulation of dry mass of plants, the productivity and quality of soybeans, in addition to benefiting nodulation when combined with co-inoculation of Bradyrhizobium ssp. and Azospirillum brasilense.

Carbon dots in biosensing have advanced significantly, adding improvements to different detection techniques. In this study, an amperometric immunosensor for Salmonella Thyphimurium was designed using antibodies labeled with carbon dots (Cdots) from pequi almond (Caryocar brasiliensis). Cdots were synthesized by pyrolysis and characterized by FTIR, UV/fluorescence, electrochemistry, zeta potential, and transmission electron microscopy (TEM). A particle size of 6.80 ± 2.13 nm was estimated, and the zeta potential was - 47.4 mV, indicating the preponderant presence of acidic groups, as confirmed by FTIR. The impedance evaluation of the response of biosensors assembled for live (Rct = 13.4 kΩ) and dead (Rct = 499.7 Ω) Salmonella showed a significant difference in their values, in agreement with chronoamperometric analyses, which had their current values drastically reduced from - 2.2 mA (live) to 0 mA (dead). An analytical curve for Salmonella was established with the limit of detection lower than 1 CFU/mL. This electrochemical biosensor using pequi carbon dots for antibody labeling showed promising results for detecting the pathogen. Thus, carbon dots can be used as substitutes for enzymes in labeling antibodies used in the design and production of sensors.

The objective of this study was to investigate the early diagnostic value of nanopore sequencing in alveolar lavage smear-negative pulmonary tuberculosis (PTB). A prospective study was conducted on patients hospitalized at Zhuzhou Central Hospital from October 2021 to June 2022 and suspected to have PTB. Alveolar lavage fluid specimens were collected from these patients and simultaneously subjected to centrifugal bacterial collection smear method in a sandwich cup, bifidobacteria solid culture (referred to as culture), Mycobacterium tuberculosis-DNA (TB-DNA), and nanopore sequencing for detection of Mycobacterium tuberculosis. These patients were ultimately diagnosed with smear-negative PTB. The final clinical diagnosis was used as a reference to compare the diagnostic efficacy of Nanopore sequencing, culture, and TB-DNA for PTB. The results showed that the positive rates detected by nanopore sequencing, culture, and TB-DNA in the 103 suspected tuberculosis patients were 73.8%, 13.6%, and 33.0%, respectively. The sensitivity of nanopore sequencing was significantly higher than culture (P < 0.001) and TB-DNA (P < 0.001) for the identification of smear-negative PTB. Similarly, the positive rate of TB-DNA was also significantly higher than that of culture (P = 0.001). In conclusion, nanopore sequencing exhibited the highest sensitivity for the rapid diagnosis of Mycobacterium tuberculosis in alveolar lavage fluid specimens, using clinical diagnosis as a reference standard, and it could improve the PTB clinical diagnosis.