Antioxidant and antimicrobial activity of red propolis embedded mesoporous silica nanoparticles.

This work brings the promise of MCM-41 mesoporous silica as a vehicle for red propolis for the development of controlled release drugs and delivery to a specific target site. The synthesis of MCM-41 by the sol-gel method with a pore size of approximately 3.6 nm and the incorporation of red propolis extract by the physical adsorption method in ethanolic medium were easily accomplished with around 15% encapsulation. MCM-41 and MCM-41 with red propolis (MCM-41/Pr) were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermal analysis, N2 adsorption-desorption, scanning electron microscopy, and an ultra-high-performance liquid chromatography-diode array detection (UPLC-DAD). In vitro release of encapsulated red propolis was analyzed in phosphate buffer at pH 7.2, 7.4, and 7.6. An in vitro test for MCM-41/Pr antioxidant activity was performed using 2,2-diphenyl-1-picrylhydrazyl as well as analysis of antibacterial activity against Staphylococcus aureus by the well diffusion method. UPLC-DAD analysis showed that the integrity of the red propolis constituents was maintained after the embed process, and the antioxidant and antibacterial activities were preserved.

Molecular mechanisms of membrane impermeability in clinical isolates of Enterobacteriaceae exposed to imipenem selective pressure.

Intrinsic mechanisms leading to carbapenem-induced membrane impermeability and multidrug resistance are poorly understood in clinical isolates of Enterobacteriaceae. In this study, molecular behaviours during the establishment of membrane impermeability in members of the Enterobacteriaceae family under imipenem selective pressure were investigated. Clinical isolates (n = 22) exhibiting susceptibility to multiple antibiotics or characterised as extended-spectrum ß-lactamase (ESBL)- or AmpC-producers were submitted to progressive passages on Mueller-Hinton agar plates containing subclinical concentrations of imipenem [0.5 × the minimum inhibitory concentration (MIC)]. Changes in outer membrane permeability were evaluated by determination of antimicrobial MICs, sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), and gene expression analysis related to membrane permeability (i.e. omp35-like, omp36-like and acrA) and regulatory mechanisms (i.e. marA and ompR) by quantitative reverse transcription PCR. Following imipenem induction, 73% of isolates showed increased carbapenem MICs by ≥2 doubling dilutions. At an early stage of treatment, imipenem modulated the expression of porins and efflux pump genes, represented by a reduction of 78% in omp36-like and a two-fold increase in acrA expression. Transcriptional factors marA and ompR were also affected by imipenem induction, increasing mRNA expression by 14- and 4-fold, respectively. High marA expression levels were associated with higher values of acrA expression. These results suggest that imipenem is an important factor in the development of an adaptive response to carbapenems by regulating key genes involved in the control of efflux pumps and porins, which could lead to a multidrug-resistant profile in clinical isolates, contributing to possible treatment failure.

Complete Genome Sequence of Lactococcus lactis Strain AI06, an Endophyte of the Amazonian Açaí Palm.

We report the genome, in a single chromosome, of Lactococcus lactis strain AI06, isolated from the mesocarp of the açaí fruit (Euterpe oleracea) in eastern Amazonia, Brazil. This strain is an endophyte of the açaí palm and also a component of the microbiota of the edible food product.