Brazilian Journal of Microbiology最新文献

The bioremediation potential of the Acinetobacter venetianus AMO1502 strain, a microorganism isolated from the oil collected from the spill off the Brazilian coast in 2019, was investigated using diesel oil as a hydrocarbon source. A. venetianus AMO1502 was able to grow in a medium containing only non-sterile diesel oil as a carbon source. In the bioprocesses using 0.5% and 1.0% (v/v) diesel oil, all compounds were completely degraded after 168 h, while the biodegradation percentage decreased with increasing diesel oil concentration. The surfactant compounds produced formed stable emulsions with diesel oil and kerosene as hydrophobic substrate, reaching emulsification indexes of 50-65%. A reduction in the surface tension of the medium was observed, decreasing by up to 65.9% (from 68.5 mN/m to 23.4 mN/m). These results demonstrate that the isolated strain, A. venetianus AMO1502, efficiently metabolizes hydrocarbons and produces surface-active compounds, highlighting its potential application in the bioremediation of petroleum-derived compounds.

Animal-derived foods (ADF) are carriers of toxin-producing multidrug-resistant (MDR) S. aureus strains, posing a global food safety risk. We evaluated the toxin and biofilm production capabilities of S. aureus isolates from ADF marketed in Assam, India. Of the 138 staphylococcal isolates, 29 (21.01%) were identified as S. aureus, mostly isolated from raw milk. Resistance to chloramphenicol (13.79%), erythromycin (68.96%), penicillin (93.10%), enrofloxacin (20.68%), tetracycline (55.17%), trimethoprim-sulfamethoxazole (20.68%), linezolid (6.89%), cefoxitin (55.17%), and oxacillin (48.27%) was noted. Approximately 82.75% isolates were MDR, whereas 27.58% carried mecA gene, indicating methicillin-resistant S. aureus. PCR toxinotyping revealed pvl (20.69%), sea (37.93%), and sed (17%) genes. Additionally, 6.89% isolates harbored seb, sei, and tst genes; all lacked eta, etb, see, seg genes. A significant difference (P < 0.05) was observed in sea and sei genes across food sources. Biofilm-forming genes were detected as icaA (65.51%), icaB (34%), icaC (48.27%), icaD (27.58%), clfA (51.72%), clfB and fnbA (44.82%). At least one biofilm-associated gene was found in 72.41% of isolates, while two or more genes were present in 80.95%. Approximately 87.5% of mecA-positive isolates contained at least one biofilm-associated gene. A significant difference (P < 0.05) was noted in icaA, icaD, clfB, and fnbA across the different ADF sources.

This study characterized the biology of Bovine Papillomavirus (BPV) in cattle from Pernambuco, Brazil, comparing viral load and gene expression between papillomas (warts) and blood. A total of 89 samples (46 for viral load, 43 for gene expression) were analyzed, all previously positive for BPV-1, -2, or -6. After simultaneous DNA/RNA extraction and cDNA synthesis, viral load was quantified via qPCR targeting the L1 gene, while expression of regulatory (E5/E7) and structural (L1) genes was assessed by RT-PCR. BPV-2 exhibited significantly higher viral load in warts (15.20 ± 45.50 log₁₀ copies/µL) versus blood (3.45 ± 6.20; p < 0.01), with greater presence in adult cows (p = 0.02) and symptomatic animals (p = 0.03). Expression of the structural gene L1 (BPV-2) was more frequent in lesions (47.8%) than in blood (25%), and a strong correlation existed between BPV-1 presence and E5 expression (φ = 0.65; p < 0.001). Warts showed higher genetic diversity (Shannon index H = 1.25 vs. 0.78 in blood) and a 4.3-fold higher probability of coinfection by multiple viral types (OR = 4.3; 95% CI 1.2-15.8), with clonal predominance of BPV-2 (84.6% of samples). The absence of negative correlations suggests viral coexistence without mutual inhibition. It is concluded that papillomas are the primary site of active BPV replication and expression, especially for type 2. Viral coexistence may promote infection persistence and lesion chronicity.

Dental caries is a highly prevalent multifactorial oral disease that can cause both local and systemic lesions. The aim of this study was to evaluate the in vitro antiseptic effect of a topical solution containing polyhexamethylene guanidine hydrochloride (PHMGH) and its possible toxic effects in vivo. PHMGH was tested (0.31-625.0 ppm) against Streptococcus mutans, Streptococcus sanguinis, Streptococcus salivarius, Streptococcus mitis, Streptococcus sobrinus, Lactobacillus casei, and Enterococcus faecalis by determining the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), minimum biofilm inhibitory concentration (MBIC₇₅), fractional inhibitory concentration index (FICI), and bactericidal kinetics. The polymer was effective against all microorganisms, with MIC and MBC ranging from 0.31 to 1.24 ppm; lower values were observed especially against S. mitis and E. faecalis when compared to commercial chlorhexidine digluconate. PHMGH inhibited 75% of the microbial biofilms, including S. mutans, with the MBIC₇₅ of PHMGH and CLX being similar for this microorganism. The combination of the polymer with CLX exerted indifferent effects against the cariogenic microorganisms. Regarding bactericidal kinetics, the polymer caused higher percent reductions in the microorganisms than CLX; at concentrations of 3.000 and 1.000 ppm, with 2 and 4 min of exposure, respectively, inducing 100% bacterial death. Given the promising results, rats received daily oral instillations of four drops of PHMGH at a concentration of 625 ppm for 90 days, mimicking a mouthwash. None exhibited alterations in mucosae or tongue, as well as no body weight and histological changes were observed in the oral mucosa, tongue, esophagus, stomach, and intestine. The toxicological evaluation showed that the treated animals did not present significant alterations in the parameters of hepatotoxicity and nephrotoxicity and DNA damage. Regarding the histopathological analyses of the digestive organs, there were no statistics differences, except for the mononuclear inflammatory infiltrate in the intestinal mucosa, which was significantly higher in treated animals. Under the present experimental conditions, PHMGH exerted in vitro antimicrobial activity against dental caries microorganisms, with no evidence of in vivo toxicity; thus, it becomes a promising and less costly option for the development of oral antiseptic products.

Aquitalea has mainly been identified from freshwater environments, including lakes, springs, waterfalls, and wetland-associated habitats. Notwithstanding the importance of wetland bacteria in mineral processes, knowledge about this genus from cave aquatic ecosystems is limited. Here, we investigated the presence of Aquitalea spp. in freshwaters from Roraima Sur Cave (Guayana Highlands), the world's longest and deepest quartzite karst system, using culture, microscopy and 16S rRNA gene sequencing. Although initially we attempted Helicobacter isolation using HP selective medium, this approach unexpectedly revealed four clones with nearly complete 16S rRNA sequences showing 99.34-99.49% identity to Aquitalea aquatica strain HSC-21Su07. Phylogenetic analysis positioned these clones within the Aquitalea genus, forming a clade with A. aquatica, A. aquatilis, and A. palustris. Furthermore, fluorescent in situ hybridization (FISH) with a eubacterial probe detected coccoid red-fluorescent cells in HP enrichments. Such morphology suggests the typical size and volume reduction experienced by rod gram-negative bacteria in the viable but non culturable state, not previously described in this genus. Given the limited microbial exploration in subterranean silica ecosystems, targeted cultivation of Aquitalea spp. is crucial to uncover novel species and elucidate their physiological adaptations to oligotrophic conditions. Our findings represent the first report of these bacteria within a quartzite cave, extending their known habitats and laying the groundwork for investigating their possible ecological role, as well as putative associations with geochemical processes within silica-rich, energy-deprived environments of evolutionary importance on Earth.

The present study examines the role of specific abiotic factors, including nitrogen source, pH, and iron concentration in regulation of siderophore production in five local cyanobacterial isolates (Anabaena sp., Synechococcus sp., Phormidium sp., Neowestiellopsis sp., and Cyanobium sp.) from Meghalaya, Northeast India. To quantify siderophore production, Chrome Azurol S (CAS) liquid assay was used. Maximum siderophore production in tested cyanobacteria occurred during the late exponential phase under iron-limiting conditions, with Synechococcus sp. peaking at 53.62% and Anabaena sp. at 47.32%. Production peaked at 30 µM iron and decreased with higher concentrations. Optimal synthesis occurred at pH 7.0, with reduced activity in more acidic or alkaline conditions. Nitrogen sources also influenced production, with nitrate supplementation yielding the highest levels. Synechococcus sp. and Anabaena sp. produced both hydroxamate and catecholate siderophores, while Phormidium sp., Neowestiellopsis sp., and Cyanobium sp. predominantly produced hydroxamate siderophores. The study demonstrates that several abiotic factors, including pH, iron availability, and nitrogen source, had significant impact on siderophore production. Of the five isolates, Anabaena sp. and Synechococcus sp. are promising candidates for use as biofertilizers due to their high hydroxamate and catecholate siderophore synthesis under all tested abiotic factors.

Previously, five strains of Lactiplantibacillus plantarum (L. plantarum) isolated from various algerian fruits: white mulberries (Morus alba L.), prickly pears (Opuntia ficus-indica), dates (Phoenix dactylifera L.) and figs (Ficus carica) have been shown to possess probiotic potential. In this study, we demonstrate their capacity to produce exopolysaccharides (EPS). Initially, physicochemical properties (moisture, ash, fat, carbohydrate and protein) of EPS were determined. Then, monosaccharide composition of this EPS was determined by Thin-Layer Chromatography (TLC) and High-Performance Liquid Chromatography (HPLC). Results showed that the EPS was a polymer of glucose. Characterization of the structure and functional groups of the EPS was conducted via Fourier Transform Infrared Spectroscopy (FT-IR). Results revealed the presence of characteristic absorption peaks of most of the polysaccharides. The UV-absorption also showed a lack of any absorption in the range of 250 and 280 nm. The antioxidant activities were also studied. The 2,2-Diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity of EPS was found to be 87.285 ± 2.815% at 10 mg/ml for EPS-FB23. While the maximum scavenging percentage of EPS-F8 was about 77.43 ± 2.07% at 10 mg/ml for the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS). For the reducing power analysis, EPS-F8 reached a maximum absorbance of 0.903 ± 0.074 at 20 mg/ml. Our findings proved that EPS from L. plantarum F8 and L. plantarum FB23 strains exhibit strong antioxidant activities, suggesting their potential use as natural antioxidants in health-promoting applications. The entire methodology is summarized in a graphical abstract.

Bacterial resistance, oxidative stress, inflammation, and cancer pose significant global health concerns. Current treatment protocols prove inadequate owing to adverse reactions and the emergence of resistant strains. In this context, this study explores the biomedicinal properties of an underexplored marine actinobacterium Streptomyces kunmingensis. Antibacterial activity inferred that the ethyl acetate extract of S. kunmingensis strenuously inhibited the growth of bacterial pathogens and violacein production by Chromobacterium violaceum. The extract effectively neutralized DPPH radicals (18.7%-85.5%) and affirmed its strong antioxidant properties. Anti-inflammatory activity (19.4%-80.6%) showed dose-dependent inhibition of hemolysis in red blood cells, and anti-arthritis activity (14.2%-74.5%) was confirmed by protein denaturation assay. Anticancer potential against A549 recorded an IC₅₀ value of 27.5 µg/mL. Toxicity assessment using Artemia salina recorded LC₅₀ values of 92.41 and 16.6 µg/mL after 24 h and 48 h. Spectroscopic (HPLC, FT-IR and GC-MS) characterization of the extract indicated fatty acids (28.125%) and iodinated hydrocarbons (28.125%) as the predominant categories of bioactive compounds. Metabolomic profiling by heatmap was used to elucidate the relationships among bioactive compounds. Molecular docking of the identified compounds against lung cancer (EGFR), inflammatory (TNF) and Staphylococcal protein A (SpA) virulence proteins revealed variation in binding affinity and further bolstered that Glutaric acid, (2-methylcyclohex-1-enyl) methyl tridec-2-yn-1-yl ester and N-benzoyl-1-ethoxymethanimidothioate are the promising bioactive molecules. To the best of our knowledge, this is the first report identifying these compounds as lead molecules with potent antibacterial and anti-inflammatory properties.