Brazilian Journal of Microbiology最新文献

Soil cyanobacteria are considered pioneer microorganisms in the formation of biocrusts, which, in turn, are recognized as ecosystem engineers in edaphic environments due to their influence on erosion control, nutrient cycling, and water dynamics in the soil. Thus, cyanobacteria have considerable potential for use in the recovery of degraded soil. However, greater knowledge on the ecophysiological characteristics of biocrust-forming cyanobacteria is needed. Therefore, the aim of the present study was to assess the development of Scytonema hyalinum and Leptolyngbya sp. (cyanobacteria) under different conditions of water availability and investigate the improvement in soil quality. The strains were inoculated in Petri dishes containing soil collected from a desertification-prone region. Water availability (with and without water limitation) was controlled over 78 days of the experiment. Cyanobacterial development (measured by chlorophyll-a concentration) was better in treatments without water limitation. Higher water availability favored the formation of biocrusts by Leptolyngbya sp., which increased soil resistance, and the vigorous growth of S. hyalinum, whose trichomes aggregated on the soil surface and also contributed to greater soil stability. The results confirmed that water is an important factor in the development of both strains. More importantly, the results demonstrated that, due to their distinct eco-physiological characteristics, the species have the potential to be used complementarily in restoration projects for degraded areas, as Leptolyngbya exhibited a greater capacity for soil stabilization, while S. hyalinum exhibited greater growth.

Fungal diseases associated with wild animals have been described, showing increased frequency and mortality or change in populations at risk. The new animal host in fungal infection is an important epidemiologic issue to understand the transmission and spread of fungus in the environment and the threat to public health. Histoplasmosis is a mycosis widely distributed throughout the world with a respiratory and systemic presentation reported in domestic and wild mammals, and is potentially fatal in immunosuppressed and immunocompetent individuals humans and not humans. Candidiasis is an opportunistic fungal disease reported in numerous species of birds and wild mammals, such as parakeets, dolphins, beavers, guanacos, and porcupines. To our knowledge, the first case of simultaneous co-infection of Histoplasma capsulatum and Candidia tropicalis in Coendou longicaudatus boliviensis (neotropical porcupine) is described through clinical, microbiological, and pathological diagnosis and confirmation with DNA sequencing. Both these fungi pose risks to public health associated with environment dissemination and antifungal resistance, and it is important to develop preventive diagnostics to adopt risk reduction measures.

Dengue virus (DENV) is an RNA virus belonging to the Flaviviridae family, comprising four antigenically distinct serotypes. Dengue is the primary arthropod-transmitted virus globally, posing a significant public health challenge, especially in Brazil, where the largest outbreak of Zika virus (ZIKV) was also recorded in 2016. ZIKV shares genomic and structural similarities with DENV, and their co-circulation in Brazil provides evidence of co-infection. The innate immune response against DENV and ZIKV is mediated by pattern recognition receptors that initiate intracellular signaling, leading to antiviral or inflammatory responses. This study aims to better understand the innate immune response to ZIKV in macrophages previously infected with DENV. To achieve this, bone marrow cells from C57BL/6 mice were differentiated into macrophages (BMDMs) and independently infected with each of the four DENV serotypes for 12 h, followed by ZIKV infection for an additional 12 h. Twenty-four hours post-infection, macrophage activation markers CD86 were assessed using flow cytometry and fluorescence microscopy. Pro-inflammatory and antiviral gene expressions were evaluated by qPCR. IFN-β was found to be down-regulated in all analyzed groups. No differences in CD86 expression were observed in ZIKV-infected BMDMs previously infected with DENV, except for serotype 4, which showed an increase in both activation markers. Conversely, TNF-α and IL-1β were down-regulated compared to non-infected or only DENV4-infected cells, correlating with increased cell viability and decreased production of the cytokine TNF-α. Bioinformatic analysis suggested that the expression of both cytokines might be regulated by miRNAs, including miR-181a-5p, which is also up-regulated in the innate immune response. Taken together, the results indicated that co-infection with DENV serotype 4 and ZIKV in mice BMDMs increases the expression of CD86, promoting macrophage activation, but reduces the expression of pro-inflammatory genes TNF-α and IL-1β, indicating enhanced cell viability what can be modulated by miRNAs.

Antibiotic resistance is a major clinical and public health problem. Non-steroidal anti-inflammatory drugs (NSAIDs) could increase the susceptibility of bacteria to antibiotics and have shown broad antimicrobial activity. In this work, the effect of Diclofenac sodium alone and in combination with Gentamicin on the expression of efflux pump genes and some virulence traits in clinical isolates of P. aeruginosa was investigated. The checkerboard titration assay was used to evaluate the synergistic effect of Diclofenac sodium and Gentamicin. The relative expression of MexAB-OprM and MexXY-OprM efflux pump genes was determined using qPCR. The impact of drugs on the activity of the efflux pump and some virulence traits, including biofilm formation, swarming, swimming and twitching, and bacterial proteolytic and hemolytic activities were assessed. The minimum inhibitory concentration (MIC) of Diclofenac sodium and Gentamicin for clinical P. aeruginosa strains was 5120 and 128 µg/mL and the drugs showed synergic antibacterial activity. Diclofenac sodium reduced the expression of the mexB, mexX, and mexY genes, and increased the expression of the mexA and oprM genes. In addition, Diclofenac sodium alone and in combination with Gentamicin inhibited the activity of the bacterial efflux pump and the simultaneous treatment of P. aeruginosa with Diclofenac sodium and Gentamicin significantly reduced biofilm formation, bacterial motility, proteolytic (40.78%) and hemolytic (85%) activities compared with untreated group. This study addresses clinically relevant questions about the efficacy and potential synergistic effects of diclofenac sodium and gentamicin in treating P. aeruginosa infections that can be applicable to clinical practice.

Escherichia coli strains are naturally susceptible to polymyxins. The frequency of polymyxin resistance in E. coli associated with chromosomal mutations is usually low (0.2-0.6%). Here, we report polymyxin-resistant E. coli strains isolated from flies (Diptera: Muscomorpha) and animals (bovine, equine, canine, and sheep) cohabitants on two dairy farms, A and B (Botucatu, State of Sao Paulo, Brazil), in 2015. We isolated 877 E. coli from the external surface of flies and healthy animal feces. The screening of polymyxin-resistant E. coli was performed using MacConkey agar with polymyxin B (2 µg/mL). We detected a high percentage of polymyxin-resistant isolates from flies (33.33%; 66/198) and farm animals (46.09%; 313/679). Fisher's exact test revealed no associations between polymyxin resistant and multidrug resistant strains. We investigated mcr genes (mcr-1, mcr-2, mcr-3, mcr-4, and mcr-5) using PCR, and five E. coli from calves (farm B) present the mcr-1 gene. Sanger sequencing and conjugation assays were performed for gene confirmation. All five mcr-1-positive E. coli showed fingerprints more than 80% similar assayed by pulsed-field gel electrophoresis. The minimum inhibitory concentrations (MICs) for polymyxin B against mcr-1-positive E. coli were 4 µg/mL (two strains), and 8 µg/mL (three strains). Whole-genome sequencing showed mcr-1.1 gene in the IncX4 plasmid and a class 1 integron unusual harboring sul3 and qacL as a non-variable structure. In Brazil, the therapeutic use of polymyxin is allowed, but stewardship in dairy cattle is uncommon; thus, our data indicate a probable selection of polymyxin-resistant strains related to environmental pressure.

Bats play an important role in global microbial ecology, as they are the host of various microbes. Carollia perspicillata is one of the most popular bat species in zoos. The influence of the captive environment on the gut microbiota of this species is underinvestigated. In this study, we compared gut microbiota composition, diversity, and the potential functional activity of wild and captive C. perspicillata from Panama and Russia (Moscow Zoo), respectively, based on high-throughput 16S rRNA sequencing data. The abundance of 13 bacterial phyla and 35 bacterial genera significantly differed. Environment- and farm animal health-related bacteria (Mannheimia, unclassified Pasteurellaceae, Staphylococcus, and Mycoplasma) dominated wild bats, while bacteria important for public health (Bacteroides, Clostridium sensu stricto 1, and Acinetobacter) were higher in zoo bats. We also observed significantly greater alpha diversity in zoo bats, while there were no significant differences in beta diversity. These findings were accompanied by significant differences in the abundance of 32 functional pathways of gut bacteria, which are probably associated with the different diets of wild and zoo bats. This study shows that the rearing environment significantly affects the gut microbiota of C. perspicillata and highlights that the outcomes of microbiome research of captive bats need to be interpreted with care. Such differences in gut bacterial communities should be the basis for the development of new handling and veterinary care protocols, and also be the justification for further studies of the impact of microbiota of wild and zoo bats on One Health.

The objective of this study was to optimize the culture medium for enhanced production of Bacillus velezensis AP-3 endospores using both liquid and solid-state fermentation techniques. Additionally, the study aimed to assess the stability of endospores in powder formulations containing talc and potato starch, and to evaluate the growth-promoting effects of these formulations on bean plants. Further, we evaluated the inhibition of mycelial growth of Sclerotinia sclerotiorum and Fusarium oxysporum f. sp. lycopercisi by metabolites produced by this bacterial strain. The plant growth promotion assay evaluated these formulations across various application methods: seed treatment, sowing furrow application, and a combination of both. Adjustments to culture medium significantly influenced the endospore yield of B. velezensis. Solid-state fermentation in rice flour and potato starch yielded up to 2.06 × 10⁸ and 1.82 × 10⁸ CFU g^- 1 after 7 days in a 60% moisture medium, respectively. Conversely, submerged fermentation in molasses + cottonseed flour medium produced 1.7 × 10⁹ CFU mL^- 1 (viable endospores) in 3 days. The powder formulations showed high stability, maintaining viability for up to 226 days at room temperature. This bacterial strain effectively inhibited the mycelial growth of target fungal pathogens and promoted bean plant growth, particularly by enhancing root development. These findings highlight the versatility of B. velezensis AP-3 in producing endospores through two fermentation methods, its extended shelf-life as a wettable powder formulation, and its efficacy both as biocontrol agent and plant growth promoter, contributing to a sustainable agriculture.

Hemotropic Mycoplasma spp., also known as Hemoplasmas, infect several species of domestic and wild animals, including humans. Although infections in wild animals are mostly asymptomatic and chronic, there is a risk of spreading the patogen to other susceptible animals. They can cause death in immunosuppressed mammals, and have implications for the conservation of already threatened wild mammals. The objective of this study was to report on the molecular detection of Mycoplasma spp. hemotropic. in wild mammals run over in the Southern Brazil, describing new findings of hemoplasmas in this region. Carcasses of 24 road-killed wild animals were collected on the highways of cities belonging to the Pelotas microregion, in the south of RS, Brazil, and were necropsied. Ectoparasites were removed and classified according to morphological taxonomic keys. Blood samples from all animals were collected and genomic DNA was extracted. Polymerase chain reaction (PCR) amplification targeting the 16S rDNA and 23S rRNA genes revealed the presence of Mycoplasma spp. DNA in blood samples from 87.5% of animals. This study reports the first molecular finding of hemotropic mycoplasma in Brazilian guinea pig (Cavia aperea) and pampas fox (Lycalopex gymnocercus). The detection of hemoplasma in different host species demonstrates the spread of the agent among wild mammals in southern Brazil.

Fusarium oxysporum is a widely distributed phytopathogen that affects agricultural crops and has demonstrated relevance in human and veterinary medicine. The virulence of this fungus involves factors such as mycotoxins, immunomodulatory proteins, and the ability to form biofilm. We assessed the pathogenicity of F. oxysporum in its planktonic form, as well as the influence of the extracellular matrix (ECM) from its biofilm on T. molitor larvae and cell culture. F. oxysporum inoculum was injected into larvae at different concentrations, and the survival curve was observed over 10 days. To evaluate the effects of ECM components, biofilms of 24, 72, 96, and 168 h of maturation were used. After extracting the ECM from these biofilms, it was injected into the larvae to assess the hosts response. For the cytotoxicity test of the ECM, were used on Vero cells. The increase in fungal inoculum concentrations was directly proportional to the larval mortality rate. When larvae were infected with the ECM, there was a 40% mortality rate and signs of weakness in the surviving larvae. Furthermore, biofilm metabolites showed cytotoxic effects, with reductions in cellular activity ranging from 20 to 49%. This alternative host model proved effective in investigating the fungal pathogenicity. Additionally, ECM components negatively affected cell viability, suggesting their importance in the damage caused by the fungus in host tissues. This study provides insights for the first time into F. oxysporum virulence and highlights the importance of considering the biofilm ECM in the context of fungal infections.

The aim of this study was to evaluate the antifungal activity of Thymus vulgaris essential oil (TEO) against fungal isolates from cheese and its potential as an active component in cellulose acetate films for application on cheese, and to perform the characterization of the films. The cheese rind isolates were identified as Penicillium crustosum QCP1 and Aspergillus flavus QCA2. TEO exhibited significant in vitro inhibitory activity against all isolates, with inhibition zones exceeding 40.0 mm and minimum inhibitory concentrations (MICs) of 1.0 µL mL⁻¹ and 0.8 µL mL⁻¹ for P. crustosum QCP1 and A. flavus QCA2, respectively. Incorporating TEO into cellulose acetate films altered the film's physical properties, particularly morphology and elongation. The control film, composed solely of acetate, showed the lowest values for most properties evaluated, except for tensile strength (MPa) (38.89 ± 5.29). For water permeability and water vapor permeability, no significant differences were observed between the control film and the active film containing TEO at tenfold MFC concentrations for each isolate. In in vitro tests with the active film, P. crustosum QCP1 demonstrated higher sensitivity; however, the active film effectively inhibited the growth of both fungal isolates on cheese slices for 30 days. It was concluded that TEO has antifungal potential against isolates in more than one type of methodology and, when added to cellulose acetate film, was effective in controlling fungal mycelial growth, both in vitro and in situ, extending shelf life by up to 2 times, indicating a promising application as active packaging in cheeses.