Brazilian Journal of Microbiology最新文献

The study report the antifungal effectiveness of Melaleuca alternifolia essential oil (MAEO) and its nanoencapsulated form (Ne-MAEO) against the selected fungal species Aspergillus flavus, A. niger, Fusarium oxysporium, and Penicillium glaucum and explored its mode of action. The chemical components of MAEO (γ-terpinene (13.69%), and terpinen-4-ol (33.94%) were explored by Gas chromatography-mass spectrometry. The Ne-MAEO was fabricated using chitosan-cinnamic acid gel and characterisation was done for size and functional group interaction and crystallinity by FTIR, DLS and XRD. The minimum inhibitory concentration was ranged between (2.0 to 4.0 µl/ml) against the growth test fungal species, while the aflatoxin B₁ inhibitory potential was reported at 3.0 µl/ml. Furthermore, Ne-MAEO compromised the membrane integrity of cells leading to a decrease in ergosterol content, leakage of cellular content (cation leakage and 260/280 absorbing materials), decrease inmethylglyoxal level, distortion of spore and hyphae, elevated MDA contents, and antioxidant defence system. Further, Ne-MAEO extend the shelf-life of maize seeds against the fungal deterioration without any significant effects on seed germination, hence, it could be used as an eco-friendly alternative to commercial fungicides to protect post-harvest fungal deterioration of food product.

This study investigated the prevalence of upper respiratory tract disease (URTD) pathogens in domestic cats during the SARS-CoV-2 pandemic in southern Brazil, focusing on the detection of feline herpesvirus-1 (FHV-1), feline calicivirus (FCV), Mycoplasma felis, Chlamydia felis, and SARS-CoV-2. A total of 120 cats presenting URTD symptoms and with recent contact (within 15 days) with SARS-CoV-2-positive tutors were analyzed. The detection rates were 38.3% for FHV-1, 34.1% for FCV, 43.3% for M. felis, 19.16% for C. felis, and 1.2% for SARS-CoV-2. Co-infections were common, affecting 64.45% of cases, with M. felis as the most frequent mono-infection and FHV-1 and M. felis as the predominant co-infection. Significant associations were observed between specific host factors and pathogen presence; non-neutered cats and those with outdoor access had higher odds of infection. Retroviral infections (FIV and FeLV) were found to increase susceptibility to URTD agents, particularly C. felis and FCV. Clinically, sneezing and nasal discharge were prevalent in over 90% of cases, and conjunctivitis was strongly linked to C. felis and FHV-1. Despite concerns surrounding the zoonotic potential of SARS-CoV-2 during the COVID-19 pandemic, the virus played a limited role, as only one cat tested positive for SARS-CoV-2 RNA. These findings emphasize the importance of focusing on established URTD pathogens for feline health management, even amid global health events.

Background: As global animal husbandry begins to reduce the use of antibiotics, finding safe and effective alternatives to antibiotics has become the key to ensuring the healthy and sustainable development of the industry. Probiotics are regarded as one of the most potential alternative strategies because of their functions of regulating intestinal microecological balance and inhibiting pathogenic bacteria.

Objective: This study was performed to determine the potential probiotic Enterococcus faecalis strains from the feces of healthy lambs.

Methods: One hundred and fifty-one rectal swabs were collected. BHI (brain heart infusion) medium was used to isolate target E. faecalis strains, and 16 S rRNA was used to identify the type of bacteria. The potential probiotic strain (L118) with high acid resistance and negative for hemolytic and gelatinase activitys was selected and its characteristics including amino acid decarboxylase activity, virulence and antibiotic resistance, bacterial adhesion to solvents, aggregation capability and cellulase and amylase activitys were determined. In addition, animal feeding experiments were conducted about the candidate bacteria in goats.

Results: A non-hemolytic and gelatinase-negative strain (L118), with a high survival rate in simulated gastric fluid (pH 3.0) and simulated intestinal fluid, was screened from 151 strains of E. faecalis. At the same time, arginine decarboxylase activity and susceptibility to antibiotics such as penicillin, amikacin, vancomycin were observed. Also, L118 displayed high hydrophobicity, low auto-aggregation ability, and strong co-aggregation capacity with pathogenic bacteria (Salmonella typhimurium, Staphylococcus aureus). It also has cellulase and amylase activities. Meanwhile, E. faecalis L118 increased the red blood cells and hemoglobin content in the blood, serum glutathione peroxidase activity and intestinal lactobacillus (P < 0.05).

Conclusion: An E. faecalis strain with high acid resistance was confirmed to possess safety and probiotic properties and provides an application and development of a new feed probiotic additive.

Providencia, as an opportunistic pathogen, can cause serious infections and increasingly poses a life-threatening risk to public health. Carbapenems were initially considered effective agents conquering such infectious; however, the emergence of carbapenem-resistant Providencia strains has been attributed to the rapid spread of carbapenemase genes. In this study, we first reported a uniquely bla_NDM-1 genetic structure that can evolve 'circular DNA'. Among 901 carbapenem-resistant Enterobacteriaceae strains examined, only one P. huaxiensis strain was identified using VITEK MS, 16S rRNA sequencing, average nucleotide identity (ANI) and the DNA-DNA hybridization (DDH). Susceptibility testing using the broth microdilution method revealed that the P. huaxiensis strain was highly resistant to carbapenems, cephalosporin, quinolone and aminoglycosides. By whole-genome sequencing (WGS) and large fragment PCRs, we characterized more than 7 resistance genes including bla_NDM-1, bla_OXA-10, qnrB, aadB, sul1, tetA and aadA1 in the P. huaxiensis strain PH1503, in which 2 copies of each the bla_NDM-1 and bla_OXA-10 genes were identified to be integrated into 3 plasmids. The bla_NDM-1 gene was integrated into a novel structure of ISCR1-trpF-bleMBL-bla_NDM-1-CatB3-Arr-3-DfrA27-AadA16-qacEdelta1-Sul1, which was present in both pPH1503-1-NDM and pPH1503-5-NDM. Moreover, the DNA sequences of the novel structure and pPH1503-5-NDM was 100% identical to each other, indicating that the novel structure may cyclize into a 'circular DNA'. To the best of our knowledge, this is the first description of a circular DNA carrying the bla_NDM-1 gene, which was identified in clinically isolated P. huaxiensis strains and appears to be stably maintained.