A Review on Enterocin DD14, the Leaderless Two-Peptide Bacteriocin with Multiple Biological Functions and Unusual Transport Pathway.

Enterocin DD14 (EntDD14) is a two-peptide leaderless bacteriocin (LLB) produced by Enterococcus faecalis 14, a human strain isolated from meconium. Studies performed on EntDD14 enabled it to show its activity against Gram-positive bacteria such as Listeria monocytogenes, Clostridium perfringens, Enterococcus faecalis, and Staphylococcus aureus. EntDD14 was also shown to potentiate the activity of different antibiotics such as erythromycin, kanamycin, and methicillin when assessed against methicillin-resistant Staphylococcus aureus (MRSA) in vitro and in vivo in the NMRI-F holoxenic mouse model. Additionally, EntDD14 has an antiviral activity and decreased the secretion of pro-inflammatory IL-6 and IL-8 in inflamed human intestinal Caco-2 cells. The genome of E. faecalis 14 was sequenced and annotated. Molecular tools such as Bagel4 software enabled us to locate a 6.7kb-EntDD14 cluster. Transport of EntDD14 outside of the cytoplasm was shown to be performed synergistically by a channel composed of two pleckstrin-homology-domain-containing proteins, namely DdE/DdF and the ABC transporter DdGHIJ. This latter could also protect the bacteriocinogenic strain against extracellular EntDD14. Here, we focus on academic data and potential therapeutic issues of EntDD14, as a model of two-peptide LLB.

Cytotoxicity and Identification of Antibacterial Compounds from Baillonella toxisperma Bark Using a LC-MS/MS and Molecular Networking Approach.

Baillonella toxisperma is a medicinal plant used in northern Gabon to treat microbial diseases. It is a plant well-known by local populations, but very few studies have focused on the molecules responsible for the antibacterial activities of B. toxisperma. This study proposes a dereplication strategy based on molecular networking generated from HPLC-ESI-Q/TOF data, allowing investigation of the molecules responsible for the antibacterial activity of B. toxisperma. From this strategy, eighteen compounds were putatively identified. All of these compounds belonged mainly to five families of natural compounds, including phenylpropanolamines, stilbenes, flavonoids, lignans and phenolic glycosides. The chemical study carried out from the bark of B. toxisperma allowed us to identify, for the first time, compounds such as resveratrol and derivatives, epicatechin, epigallocatechin and epigallocatechin gallate. In addition, antibacterial activity (diffusion method and microdilution) and cytotoxicity (Cell Counting Kit-8 (CCK-8 Assay)) in vitro were evaluated. The crude ethanolic extract, as well as the fractions of B. toxisperma, showed significant antibacterial activity. However, the ethanolic fractions F2 and F4 presented high antibacterial activity compared to the crude extract. Cytotoxicity studies on colon-cancer cells (Caco-2) and human keratinocyte cells (HaCaT) showed moderate cytotoxicity in both cell types. This study clearly shows the therapeutic potential of the ethanolic extract of the bark of B. toxisperma and provides information on the phytochemical composition and bioactive compounds of the plant.

Synthetic Flavonoid BrCl-Flav-An Alternative Solution to Combat ESKAPE Pathogens.

ESKAPE pathogens are considered as global threats to human health. The discovery of new molecules for which these pathogens have not yet developed resistance is a high medical priority. Synthetic flavonoids are good candidates for developing new antimicrobials. Therefore, we report here the potent in vitro antibacterial activity of BrCl-flav, a representative of a new class of synthetic tricyclic flavonoids. Minimum inhibitory/bactericidal concentration, time kill and biofilm formation assays were employed to evaluate the antibacterial potential of BrCl-flav. The mechanism of action was investigated using fluorescence and scanning electron microscopy. A checkerboard assay was used to study the effect of the tested compound in combination with antibiotics. Our results showed that BrCl-flav displayed important inhibitory activity against all tested clinical isolates, with MICs ranging between 0.24 and 125 µg/mL. A total kill effect was recorded after only 1 h of exposing Enterococcus faecium cells to BrCl-flav. Additionally, BrCl-flav displayed important biofilm disruption potential against Acinetobacter baumannii. Those effects were induced by membrane integrity damage. BrCl-flav expressed synergistic activity in combination with penicillin against a MRSA strain. Based on the potent antibacterial activity, low cytotoxicity and pro-inflammatory effect, BrCl-flav has good potential for developing new effective drugs against ESKAPE pathogens.

Evaluation of Antiradical and Antioxidant Activities of Lipopeptides Produced by Bacillus subtilis Strains.

This study investigated the antiradical and antioxidant potential of the three families of lipopeptides (i.e., surfactin, mycosubtilin, and plipastatin/fengycin) produced by Bacillus subtilis strains. The antiradical/antioxidant activities of highly purified lipopeptides were studied in acellular models using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, superoxide anion ( O 2 . - ), hydrogen peroxide, (H2O2) and hydroxyl radical (HO.). At a lipopeptide concentration of 500 mg.L-1, the maximum inhibition of DPPH reached 22.88% (obtained for plipastatin). Moreover, the scavenging effects of O 2 . - , H2O2, and HO. at the highest concentration tested (250 mg.L-1) were found to be 6, 21, and 3% for surfactin, 19, 9, and 15% for mycosubtilin, 21, 18, and 59% for plipastatin, 21, 31, and 61% for the mixture of surfactin/plipastatin, and 13, 16, and 15% for the mixture of surfactin/mycosubtilin, respectively. These results showed that plipastatin was the best candidate due to its antioxidant activities.

Dataset on phenotypic characterization, on protein and genome analysis of three fluorescent Pseudomonas strains from mid-mountain water.

The identification of non-fermentative Gram negative bacilli from run-off and spring water, including fluorescent Pseudomonas is very complex and investigations are needed to contribute to the systematic of these bacteria. In this dataset, the phenotypical profiles of three strains isolated from Vosges mountains first identified as Pseudomonas fluorescens were determined using APIⓇ 50 CH galleries. Then, the identification of their proteins released directly into water was carried out using tandem/mass spectrometry after separating proteins on native two-dimensional polyacrylamide gels. Finally, genotypic analysis data is presented, that illustrates biodiversity in this fluorescent bacterial group. This data is referred by a research article entitled "Fluorescent Pseudomonas strains from mid-mountain water able to release antioxidant proteins directly into water".

Fluorescent Pseudomonas strains from mid-mountain water able to release antioxidant proteins directly into water.

Little is known about fluorescent Pseudomonas and investigations are needed to help us better understand how their species work. The aim was here to mimic what naturally occurs in environmental water containing strains isolated from mid-mountain water samples and identified as Pseudomonas fluorescens by conventional biochemical techniques. Three strains were cultured before being directly inoculated into distilled water. Surprisingly, the three cell-less extracts obtained after spinning the bacterial suspensions showed strong in vitro anti-oxidative effects against superoxide anion and hydroxyl radical but with discrepancies. The extracts obtained were found to contain antioxidant proteins among other stress proteins that were released by viable bacteria. They were identified using tandem/mass spectrometry and showed different profiles in sodium-dodecyl sulfate polyacrylamide gel electrophoresis. Bacterial identification was deepened using 16S ribonucleic acid and genome sequencing analyses to explain the differences observed between strains.

The Genotyping Resistance Profile of the Pol Gene Detected in Blood of Newly Diagnosed HIV-Positive Men Is Durably Archived in the Gut Whatever the Time of Initiation of cART.

OBJECTIVE: To evaluate the mutational patterns on the pol gene of the main HIV-1 strain archived in cell genome of 10 chronically infected men according to their clinical and therapeutic history. The genotyping resistance profiles were compared between the first blood plasma available at the time of HIV diagnosis and rectal biopsies and PBMC sampled 1-5 years after the initiation of combined antiretroviral therapy (cART). METHODS: HIV-1 RNA and cell-associated HIV-1 DNA were quantified by Abbott Real-Time HIV-1 and Generic HIV® DNA cell (Biocentric) assays. The mutations in protease and reverse transcriptase genes were assessed by the Trugene® assay (Siemens). The C2V3 region was amplified to determine the viral tropism. RESULTS: In 9 patients, slight or no differences were observed between the 3 resistance profiles. Those mostly detected were related to the resistance to nucleos(t)ide (D67N, L210W, T215A, T69D) and nonnucleoside (K103N, V106I, V179I) inhibitors. In 1 rilpivirine-treated patient, the M230I mutation was detected in PBMC. No change of viral tropism was observed between samples. CONCLUSION: These data suggest that resistance mutations harbored by the main HIV strain in plasma at the time of diagnosis are durably archived in DNA cells whatever the delay between infection and initiation of therapy in patients well controlled by cART.