Brazilian Journal of Microbiology最新文献

Macrobrachium rosenbergii is a commercially important freshwater prawn cultured on a large scale mostly in south and south east Asian countries. Diseases are one of the bottlenecks for the successful culture and production of this important species. Lactococcus garvieae is a Gram-positive coccus commonly found in aquatic environments causing fish and shellfish diseases. In the present investigation, we have isolated and characterized L. garvieae, as etiological agent of white muscle disease in freshwater prawn juveniles. The infected prawn samples showing clinical signs of opaque and whitish muscles, sluggishness and mortality were collected and processed. The isolated bacterium was identified using biochemical methods and 16s rDNA sequencing and species-specific PCR. The sequence obtained revealed > 99% identity with L. garvieae reported elsewhere. Koch's postulate was experimentally established through intramuscular challenge and the infected prawn muscle revealed massive coagulative necrosis with the presence of cocci. The isolate was found to be resistant to antibiotics namely clindamycin, cefoxitin, amoxicillin and co-trimoxazole. The heavy metal tolerance assay revealed the isolate to be tolerant to Cu²⁺ and Cr⁶⁺ and less tolerant to Hg²⁺. Class I integron was also identified in L. garvieae isolate. Further, the isolate was screened for several virulence genes and found to have hemolysins 1, 2, and 3, adhesin PsaA, adhesin Pav, enolase, LPxTG 1, 3, and 4, adhesin clusters 1 and 2, and adhesin in the PCR assay. It is the first report of L. garvieae infection in freshwater prawns in India and will pave the way for developing suitable preventive measures for future sustainable culture and production of this important aquaculture species.

The aim of the present work was to screen bacterial and actinomycetes strains from the sediments of river Ganga (India) as a promising source of anti-microbial and anti-cancer agents along with spectroscopic and chromatographic identification of bio-active compounds. The strain GRS9 exhibited broad-spectrum bio-activity against all the 15-test organisms incorporated in our study with minimum inhibitory concentrations (MICs) ranging from 16 µg/ml against Staphylococcus aureus MTCC3160 to 500 μg/ml for Escherichia coli (MTCC118). The cytotoxic profile of ethyl acetate extract was also evaluated against Human Colon Cancer Cell Line (HCT116) by Neutral Red Uptake (NRU) assay, followed by in silico study to determine its pre-qualification for drug suitability. The results indicated that Streptomyces werraensis GRS9 extract possessed anti-cancer properties (IC₅₀ = 22.95 µg/ml) and found suitable for further drug development as reflected in Absorption, Distribution, Metabolism and Excretion (ADME) prediction having no violation of Lipinski's rule of five. Bioactive compounds associated with GRS9 were identified by Gas Chromatography Mass Spectroscopy (GC-MS) and Fourier Transform Infrared Spectroscopy (FTIR), revealing 29 compounds along with 10 major compounds identified via National Institute of Standards and Technology (NIST) /Wiley library. These compounds include N-(4-methyl-1-Piperzinyl)-1-Napthamide (a compound of immense pharmacological potential especially in oncology) along with anti-microbials i.e. Dodecanamide and 1,2-Benzenedicarboxylic acid, Diethyl ester. The findings revealed our sediment isolate Streptomyces werraensis GRS9 to be a suitable candidate for the isolation and purification of bio-active compounds that may act as a source of anti-microbial and anti-cancer agents.

Although less studied than its bacterial counterpart, the fungal component of the vaginal microbiota plays a critical role in maintaining vaginal homeostasis. Most research on the composition of the vaginal mycobiota has focused on pathological conditions, with relatively few studies involving healthy women. To gain comprehensive insights into the vaginal mycobiota of Algerian women in two different age groups, we performed a targeted metagenomic analysis using ITS2 region sequencing data from 14 vaginal samples collected from healthy women in reproductive and postmenopausal stages. A single dominant fungal species per individual was observed in both young and postmenopausal women, with differences in fungal community composition between the two groups being related to hormone levels. Our results show that Candida and Saccharomyces were the dominant genera in both young and postmenopausal women. Notably, the postmenopausal group had twice as many species, along with the presence of uncommon taxa such as Dipodascus and Fusarium, indicating greater taxonomic diversity. These findings suggest that menopause is associated with increased microbial variability, likely due to hormonal changes that disrupt the vaginal environment. This study paves the way for more extensive analyses involving diverse age groups and ethnic backgrounds.

Stem rot disease (Agroathelia rolfsii) biocontrol is an environmentally safe alternative that could potentially decrease disease severity and limit plant and yield losses. In the present investigation, 11 actinomycetes isolates, recovered from disease-suppressive composts, were tested as whole cell suspensions and cell-free culture filtrates for their ability to suppress tomato stem rot and to stimulate plant growth. Five isolates (namely A5-3, A2-4, A3-4, A4-4 and A5-4), applied as cell suspensions, were found to be the most effective in suppressing disease severity by 37.5-56.2% compared to the untreated control and 25-56.2% using their cell-free culture filtrates. The in vitro antifungal activity of isolates tested and their filtrates were estimated at 58.8-88% and 59-91.3% decrease in fungus mycelial growth, respectively. As for their growth-promoting ability, tomato plants treated with A5-3, A2-4, A3-4, A4-4 and A5-4 isolates were 20-89.1% and 10.3-79% higher than A. rolfsii-inoculated and pathogen-free controls, respectively. Inoculated and uninoculated plants treated with filtrates showed significant increments in their growth parameters by 18.2-91.9% and 15.3-93.4% over control, respectively. The most bioactive isolates against target pathogen were affiliated, based on 16 S rDNA gene sequencing, to Streptomyces, Saccharomonospora and Micromonospora genera. All these isolates were shown able to produce indole-3-acetic acid. Streptomyces sp. (A5-3) and Streptomyces sp. (A5-4) displayed chitinase, protease and lipase activities together with phosphate solubilization and nitrogen-fixing abilities. Streptomyces sp. (A5-3) displayed the greatest amylolytic activity and ability to solubilize zinc and to produce siderophores and hydrogen cyanide. This investigation demonstrated that actinomycetes recovered from disease-suppressive composts can be explored as potential sources of bio-active compounds with antifungal and bio-fertilizing abilities useful for the improvement of tomato growth and health.

The present study aimed to isolate, identify and characterize the yeasts of fermented must from grapes in the São Francisco Valley region, Brazil. The grapes were collected from four vineyards in the region and taken to the laboratory for must production and strain isolation. The yeasts were identified by sequencing the D1/D2 variable domains of the largest subunit of the rRNA gene. The Saccharomyces cerevisiae strains were differentiated using the mitochondrial DNA restriction technique (RFLP-mtDNA), and compared with the commercial strains used in the region for wine production. A total of 368 yeasts were isolated, 109 of which were non-Saccharomyces and 259 S. cerevisiae. Of these, 184 were indigenous and 75 commercial varieties. Among the indigenous strains, 22 RFLP-mtDNA and two commercial profiles were characterized. The must of the samples collected was appropriate substrate for identifying and isolating the non-Saccharomyces and S. cerevisiae strains and commercial yeasts. Given that the indigenous strains were more numerous than their commercial counterparts, which were selected in countries with a temperate climate, new studies should be conducted, testing the capacity of indigenous yeasts in producing quality wines, with typicality and regional identity, some of which may become commercially viable.

Newcastle disease (ND) is an important disease and a significant concern in the poultry industry. The ND virus (NDV) is oncolytic and considered as a potential treatment for cancer treatment. Carvacrol (CVC) is a plant monoterpene known for its antimicrobial and anti-cancer properties. The effects of CVC on embryos and NDV have not been investigated yet. Chicken embryonated eggs were treated with different doses of CVC. Some were sampled on hatching day, while others were bred and immunized with ND vaccine. In another experiment, NDV was pretreated with 100, 1000 and 10,000 ppm CVC before being inoculated in ovo. Additionally, some embryonated eggs were treated with 10,000 ppm CVC and then inoculated with 100 EID50 NDV. The most damages were observed in the brain, tissue at 1000 and 10,000 ppm. LC3 staining in the brain showed autophagy at both doses, while TUNEL staining confirmed the occurrence of apoptosis at 10,000 ppm. Furthermore, in heart and renal tissues pathological alterations were detected at high dose administration. The virus yield increased in embryos pretreated with 10,000 ppm CVC. However, in the experiment where NDV was pretreated with CVC, only 10,000 ppm was virucidal, with other doses leading to an increase in virus yield. Treatment of embryos with CVC had no significant effect on the HI antibody response to the ND vaccine in the breeding period. Based on our findings, the enhancing effects of CVC on NDV proliferation and its impact on apoptosis and autophagy at high doses could be a new area of research for potential cancer treatment in resistant cancer cells.

The gut microbiome, consisting of a diverse community of beneficial bacteria, supports broiler health and performance. This study aimed to assess the impact of probiotic lactic acid bacteria supplementation on growth performance, blood parameters, and antibody response in broiler chickens. The experiment involved 108 Cobb 500 breed chicks, which were allocated into three groups: T1 (received basal diets + L. reuteri at 1 × 10⁸ CFU/mL), T2 (received basal diets + P. pentosaceus at 1 × 10⁸ CFU/mL), and T3 (control group receiving only basal diets). The chicks were assigned to these groups randomly, following a completely randomized design. The results showed that the broiler groups supplemented with either L. reuteri or P. pentosaceus probiotics exhibited significant improvements (p < 0.05) in body weight, weight gain, and feed conversion ratio throughout the study. There were no significant differences (p > 0.05) in total protein and albumin levels. At the same time, cholesterol levels were lower in the L. reuteri and P. pentosaceus-treated groups compared to the control group. Furthermore, the hemagglutination inhibition titer of Newcastle disease was significantly (p < 0.05) higher in the groups supplemented with L. reuteri and P. pentosaceus. The study also found that the lymphoid organ weight/body weight ratio was significantly higher in the L. reuteri and P. pentosaceus groups. In conclusion, the oral administration of the probiotic strains L. reuteri DSM 20016T and P. pentosaceus DSM 20206 to broiler chickens improved growth performance, reduced blood cholesterol levels, and enhanced immune function. These findings indicate that these lactic acid bacteria could be beneficial as both immunomodulators and growth promoters in broiler production.

Equine rhodococcosis is caused by Rhodococcus equi, an intracellular coccobacillus whose main virulence factor is a plasmid that harbors genes encoding proteins from the Vap family, with the vapA gene being the most important in equine isolates. Furthermore, other factors observed in R. equi strains, such as antimicrobial resistance and biofilm production, may represent significant challenges in the treatment of affected animals. The objective of this study was to characterize four isolates of R. equi from foals in the state of Pernambuco, Brazil. All isolates were identified as R. equi through biochemical tests, amplification of the choE gene, and sequencing of 16 S rRNA. PCR analysis revealed that three isolates were positive for the plasmid virulence genes (vapA, -C, -D, -E, -F, -H and traA), although vapD was absent in one of the three isolates. One isolate did not present any virulence genes, possibly due to the loss of the plasmid after repeated passages at 37ºC. In the antimicrobial susceptibility test, all isolates were susceptible to erythromycin, clarithromycin, azithromycin, rifampicin, gentamicin, and doxycycline. However, all isolates were capable of forming biofilms, with moderate biofilm formation in isolates Rhodo1 and Rhodo2, and weak biofilm formation in isolates Rhodo3 and Rhodo4, which may be associated with increased antimicrobial tolerance. This molecular characterization demonstrated, for the first time, the presence of the virulence plasmid in R. equi isolates from foals in Northeast Brazil, as well as their capacity for biofilm formation.

In the quest for sustainable fuel sources, chitin-based biorefineries are gaining recognition as chitin is the second most abundant bioresource after cellulose. This approach not only provides an effective method for converting shell waste from seafood processing into valuable bioethanol but also helps in waste management. In this study, Bacillus haynesii, a marine isolate, was investigated and this is the first report on optimisation of process parameters for chitinase production from Bacillus haynesii. The One Factor at a Time (OFAT) method was used to optimize process parameters including inoculum age, inoculum size, temperature, pH, and filling volume, with colloidal chitin identified as the best carbon source for the growth of Bacillus haynesii. The Plackett-Burman Design (PBD) was employed to screen media components, followed by optimization using the Taguchi Orthogonal Array method. The media components investigated included glycerol, yeast extract, MnCl₂·4H₂O, MgSO₄·7H2O, NH₄Cl, and colloidal chitin. As a result, the optimized media-comprising 7.5 g/L yeast extract, 7.5% (w/v) glycerol, 0.6% (w/v) colloidal chitin, 1.44 g/L MnCl₂·4H₂O, and 1.2 g/L MgSO₄·7H₂O-yielded an enzyme activity of 6.85 U/mL with a specific activity of 28.87 U/mg. Furthermore, ethanol production from chitin oligosaccharides by Saccharomyces cerevisiae was quantified using the potassium dichromate oxidation method, achieving a bioethanol concentration of 2.48% v/v from 33.18 g/L of chitin oligosaccharides. These results demonstrate the potential of Bacillus haynesii-derived chitin oligosaccharides as a promising substrate for bioethanol production.

Desmodus rotundus bats are the main reservoir for Lyssavirus rabies (RABV) in the Americas, however, knowledge of virus-host interactions in this species is very limited due to challenges associated with establishing in vivo experimental infections. In this context, cell culture becomes a valuable tool for expanding knowledge on the dynamics of RABV infection in its natural host in the Americas. This study aimed to develop and characterize a cell line from D. rotundus bat and to evaluate its susceptibility to RABV. Primary cultures of D. rotundus fetal kidney cells were immortalized using the plasmid pSV1 containing the Large T and Small T antigen gene sequences of Simian Virus 40 (SV40). The obtained clones were selected by limiting dilution and transfection was confirmed by PCR for Large T SV40 gene. The resulting cell line was named FKDR (Fetal Kidney Desmodus Rotundus). The growth curve, senescence assay, and karyotype analysis of the primary and FKDR cell cultures were performed. The susceptibility of FKDR cells to RABV was determined through direct fluorescent antibody test (dFAT), and compared with that of BHK-21, Tb1Lu, and CaroPe cells. Once immortalized, the cell adopted a fusiform appearance and showed the absence of senescence markers, chromosomal anomalies, and accelerated cell growth, compared to the primary fetal cell. The FKDR and the other cell lines used for RABV infections exhibited positive staining by immunofluorescence but no cytopathic effect. The cell line described here holds potential for studies of RABV infections in D. rotundus bats.