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Polymers Jan 2022Plant-derived essential oils (EOs) represent a green alternative to conventional antimicrobial agents in food preservation. Due to their volatility and instability,...
Plant-derived essential oils (EOs) represent a green alternative to conventional antimicrobial agents in food preservation. Due to their volatility and instability, their application is dependent on the development of efficient encapsulation strategies allowing their protection and release control. Encapsulation in Polyhydroxyalkanoate (PHA)-based nanoparticles (NPs) addresses this challenge, providing a biodegradable and biobased material whose delivery properties can be tuned by varying polymer composition. In this work, EO from Mexican oregano was efficiently encapsulated in Polyhydroxybutyrate (PHB) and Poly-3-hydroxybutyrate-co-hydroxyhexanoate (PHB-HHx)-based NPs by solvent evaporation technique achieving high encapsulation efficiency, (>60%) and loading capacity, (about 50%). The obtained NPs displayed a regular distribution with a size range of 150-210 nm. In vitro release studies in food simulant media were fitted with the Korsmeyer-Peppas model, indicating diffusion as the main factor controlling the release. The cumulative release was affected by the polymer composition, possibly related to the more amorphous nature of the copolymer, as confirmed by WAXS and DSC analyses. Both the EO-loaded nanosystems displayed antimicrobial activity against Micrococcus luteus, with PHB-HHx-based NPs being even more effective than the pure EO. The results open the way to the effective exploitation of the developed nanosystems in active packaging.
PubMed: 35012189
DOI: 10.3390/polym14010166 -
Antibiotics (Basel, Switzerland) Feb 2023Ruthenium -heterocyclic carbene (NHC) complexes have unique physico-chemical properties as catalysts and a huge potential in medicinal chemistry and pharmacology,... (Review)
Review
Ruthenium -heterocyclic carbene (NHC) complexes have unique physico-chemical properties as catalysts and a huge potential in medicinal chemistry and pharmacology, exhibiting a variety of notable biological activities. In this review, the most recent studies on ruthenium NHC complexes are summarized, focusing specifically on antimicrobial and antiproliferative activities. Ruthenium NHC complexes are generally active against Gram-positive bacteria, such as , , and are seldom active against Gram-negative bacteria, including , and and fungal strains of The antiproliferative activity was tested against cancer cell lines of human colon, breast, cervix, epidermis, liver and rat glioblastoma cell lines. Ruthenium NHC complexes generally demonstrated cytotoxicity higher than standard anticancer drugs. Further studies are needed to explore the mechanism of action of these interesting compounds.
PubMed: 36830276
DOI: 10.3390/antibiotics12020365 -
Chemical Science Nov 2023Lasso peptides are a class of ribosomally synthesized and post-translationally modified peptides (RiPPs) that feature an isopeptide bond and a distinct lariat fold. A...
Lasso peptides are a class of ribosomally synthesized and post-translationally modified peptides (RiPPs) that feature an isopeptide bond and a distinct lariat fold. A growing number of secondary modifications have been described that further decorate lasso peptide scaffolds. Using genome mining, we have discovered a pair of lasso peptide biosynthetic gene clusters (BGCs) that include cytochrome P450 genes. Using mass spectrometry, stable isotope incorporation, and extensive 2D-NMR spectrometry, we report the structural characterization of two unique examples of (C-N) biaryl-linked lasso peptides. Nocapeptin A, from , is tailored with a Trp-Tyr crosslink, while longipepetin A, from , features a Trp-Trp linkage. Besides the unusual bicyclic frame, a Met of longipepetin A undergoes -methylation to yield a trivalent sulfonium, a heretofore unprecedented RiPP modification. A bioinformatic survey revealed additional lasso peptide BGCs containing P450 enzymes which await future characterization. Lastly, nocapeptin A bioactivity was assessed against a panel of human and bacterial cell lines with modest growth-suppression activity detected towards .
PubMed: 38023510
DOI: 10.1039/d3sc02380j -
Orphanet Journal of Rare Diseases Nov 2022Individuals with familial adenomatous polyposis (FAP) harbor numerous polyps with inevitable early progression to colon cancer. Complex microbiotic-tumor...
BACKGROUND
Individuals with familial adenomatous polyposis (FAP) harbor numerous polyps with inevitable early progression to colon cancer. Complex microbiotic-tumor microenvironment perturbations suggest a dysbiotic relationship between polyp and microbiome. In this study, we performed comprehensive analyses of stool and tissue microbiome of pediatric FAP subjects and compared with unaffected cohabiting relatives through 16S V4 region amplicon sequencing and machine learning platforms.
RESULTS
Within our FAP and control patient population, Firmicutes and Bacteroidetes were the predominant phyla in the tissue and stool samples, while Proteobacteria dominated the polyp/non-polyp mucosa. A decline in Faecalibacterium in polyps contrasted with a decline in Bacteroides in the FAP stool. The alpha- and beta-diversity indices differed significantly within the polyp/non-polyp groups, with a concurrent shift towards lower diversity in polyps. In a limited 3-year longitudinal study, the relative abundance of Proteobacteria and Fusobacteria was higher in polyps compared to non-polyp and stool specimens over time. Through machine learning, we discovered that Archaeon_enrichment_culture_clone_A13, Micrococcus_luteus, and Eubacterium_hallii in stool and PL-11B10, S1-80, and Blastocatellaceae in tissues were significantly different between patients with and without polyps.
CONCLUSIONS
Detection of certain bacterial concentrations within stool or biopsied polyps could serve as adjuncts to current screening modalities to help identify higher-risk patients.
Topics: Humans; Child; Longitudinal Studies; Adenomatous Polyposis Coli; Biopsy; Microbiota; Tumor Microenvironment
PubMed: 36376984
DOI: 10.1186/s13023-022-02569-2 -
International Journal of Molecular... Oct 2019The main phospholipid (MPL) of DSM 1728 was isolated, purified and physico-chemically characterized by differential scanning calorimetry (DSC)/differential thermal... (Review)
Review
The main phospholipid (MPL) of DSM 1728 was isolated, purified and physico-chemically characterized by differential scanning calorimetry (DSC)/differential thermal analysis (DTA) for its thermotropic behavior, alone and in mixtures with other lipids, cholesterol, hydrophobic peptides and pore-forming ionophores. Model membranes from MPL were investigated; black lipid membrane, Langmuir-Blodgett monolayer, and liposomes. Laboratory results were compared to computer simulation. MPL forms stable and resistant liposomes with highly proton-impermeable membrane and mixes at certain degree with common bilayer-forming lipids. Monomeric bacteriorhodopsin and ATP synthase from were co-reconstituted and light-driven ATP synthesis measured. This review reports about almost four decades of research on membrane and its MPL as well as transfer of this research to species recently isolated from Indonesian volcanoes.
Topics: Archaeal Proteins; Calorimetry, Differential Scanning; Computer Simulation; Differential Thermal Analysis; Glycosylation; Liposomes; Phospholipids; Thermoplasma
PubMed: 31640225
DOI: 10.3390/ijms20205217 -
Frontiers in Pediatrics 2023To explore the clinical characteristics of bloodstream infection in an infant and characterize the phenotype and genotype of the isolated strains, as well as seek...
PURPOSE
To explore the clinical characteristics of bloodstream infection in an infant and characterize the phenotype and genotype of the isolated strains, as well as seek suitable infection models for assessing virulence.
METHODS
Clinical data was collected from an infant patient diagnosed with bloodstream infection. Metagenomic sequencing was performed on the isolated blood sample. The strain was isolated and underwent mass spectrometry, biochemical tests, antibiotic susceptibility assays, and whole-genome sequencing. The infection model was used to assess virulence.
RESULTS
Patient responded poorly to cephalosporins, but recovered after Linezolid treatment. Metagenomic sequencing identified as the predominant species in the sample, confirming infection. They were identified as with a high confidence level of 98.99% using mass spectrometry. The strain showed positive results for Catalase, Oxidase, and Urea tests, and negative results for Mannose, Xylose, Lactose, Mannitol, Arginine, and Galactose tests, consistent with the biochemical profile of reference standards. susceptibility to 15 antibiotics was demonstrated and no resistance genes were detected. Predicted virulence genes, including , were associated with metabolic pathways and the type VI secretion system. The infection model demonstrated dose-dependent survival rates.
CONCLUSION
The infant likely developed a bloodstream infection with due to compromised immunity. Although the isolated strain is sensitive to cephalosporin antibiotics and has low pathogenicity in infection models, clinical treatment with cephalosporins was ineffective. Linezolid proved to be effective, providing valuable guidance for future clinical management of such rare infections.
PubMed: 38188910
DOI: 10.3389/fped.2023.1303040 -
Biochimica Et Biophysica Acta.... Apr 2023The effects of naringenin and the biflavonoids amentoflavone and tetrahydroamentoflavone on select bacterial lipids (carotenoids, fatty acids, and menaquinones) and...
The effects of naringenin and the biflavonoids amentoflavone and tetrahydroamentoflavone on select bacterial lipids (carotenoids, fatty acids, and menaquinones) and membrane fluidity based on Laurdan generalized polarization were investigated. For this purpose, the pigment-forming food-associated microorganisms Staphylococcus xylosus (DSM 20266 and J70), Staphylococcus carnosus DSM 20501, and Micrococcus luteus (ATCC 9341 and J3) were studied. The results suggest an envelope stress response by microorganisms due to flavonoids and an employment of adaptive mechanisms using carotenoids, fatty acids, and menaquinones. The flavonoid monomer naringenin impacted carotenoids, fatty acids, menaquinones, and membrane fluidity. Naringenin significantly influenced the carotenoid profile, particularly by an increase in the relative proportion of 4,4'-diaponeurosporenoic acid in Staphylococcus xylosus. Amentoflavone caused changes mainly in the membrane of Micrococcus luteus and decreased the menaquinone content. Tetrahydroamentoflavone mainly affected the carotenoids in the investigated strains. The noticeably different CCS value of tetrahydroamentoflavone compared to naringenin and amentoflavone revealed further insights into the structure-dependent effects of flavonoids. This study provides valuable insights into the response of pigment-forming food-associated microorganisms to naringenin, amentoflavone, and tetrahydroamentoflavone, which is important for the targeted and safe application of the latter as natural preservatives and useful for further research on the mechanisms of action.
Topics: Flavonoids; Vitamin K 2; Carotenoids; Fatty Acids
PubMed: 36746312
DOI: 10.1016/j.bbamem.2023.184137 -
Life (Basel, Switzerland) Oct 2022An aerobic bacterium, designated as strain KD337-16T, was isolated from the fecal samples of a black pig. It exhibited spherical, non-motile and non−spore-forming,...
An aerobic bacterium, designated as strain KD337-16T, was isolated from the fecal samples of a black pig. It exhibited spherical, non-motile and non−spore-forming, Gram-positive cells. KD337-16T was identified as a member of the genus Micrococcus through 16S rRNA gene sequencing, and its closest relatives were found to be Micrococcus endophyticus YIM 56238T (99.5% similarity), Micrococcus luteus NCTC 2665T (99.1%), Micrococcus yunnanensis YIM 65004T (99.1%), Micrococcus aloeverae AE-6T (99.1%), Micrococcus antarcticus T2T (98.9%), and Micrococcus flavus LW4T (98.7%). Phylogenomic trees were constructed, and strain KD337-16T was found to form its own cluster as an independent lineage of M. flavus LW4T. Between KD337-16T and its close relatives, the average nucleotide identity, average amino acid identity, and digital DNA−DNA hybridization were below the respective species delineation thresholds at 82.1−86.6%, 78.1−86.1%, and 24.4−34.9%. The major cellular fatty acids and polar lipids were anteiso-C15:0 and iso-C15:0, and DPG and PG, respectively. The predominant menaquinone was MK-8(H2). Taken together, the results indicate that strain KD337-16T is a novel species of the genus Micrococcus, for which the name Micrococcus porci sp. nov. is proposed. The type strain is KD337-16T (=BCRC 81318T = NBRC 115578T).
PubMed: 36362904
DOI: 10.3390/life12111749 -
Scientific Reports Nov 2022This study investigated the mechanism of membrane damage by protocatechualdehyde (PCA) against Micrococcus luteus and assessed effects of PCA on the sensory and...
This study investigated the mechanism of membrane damage by protocatechualdehyde (PCA) against Micrococcus luteus and assessed effects of PCA on the sensory and physicochemical properties of pork. The mechanism of PCA inhibition on M. luteus was studied by determining the minimum inhibitory concentration (MIC) based on membrane potential, intracellular ATP concentration, intracellular pH, confocal laser scanning microscopy (CLSM), and field emission gun scanning electron microscopy (FEG-SEM). The results showed that the MIC of PCA against M. luteus was 1.25 mg/mL. Hyperpolarization of the bacterial cell membrane, a decrease in the intracellular ATP concentration, and intracellular pH indicated that PCA damaged the cell membrane of M. luteus. FEG-SEM observation revealed that PCA could cause surface collapse, cell membrane rupture, and content outflow of M. luteus. Additionally, PCA was found to inhibit increases in the total number of colonies, the thiobarbituric acid reactive substances (TBARS) value growth rate, and moisture mobility in raw pork. Additionally, it improved the color and texture of raw pork, all of which effectively prolonged its shelf life. This study will encourage the application of PCA as a natural antibacterial agent in the food industry.
Topics: Animals; Swine; Micrococcus luteus; Pork Meat; Red Meat; Adenosine Triphosphate
PubMed: 36344587
DOI: 10.1038/s41598-022-23309-3 -
Current Research in Microbial Sciences Dec 2021The proteomics and transcriptomic analysis of strain AS2 was carried out through 2D gel electrophoresis and RT-PCR. Seven protein spots were selected randomly from the...
The proteomics and transcriptomic analysis of strain AS2 was carried out through 2D gel electrophoresis and RT-PCR. Seven protein spots were selected randomly from the gel and identified through mass spectrometry. Four proteins including putative metal-dependent hydrolase TatD, thioredoxin reductase, DNA-directed RNA polymerase subunit alpha and chaperone protein DnaK were upregulated while superoxide dismutase [Mn], 3-oxoacyl-[acyl-carrier-protein] reductase FabG, and putative alkyl/aryl-sulfatase YjcS were down-regulated under arsenite stress. No significant difference was observed in gene expression analysis in the presence and absence of arsenite. The optimum arsenite processing ability was determined at 37°C (90%) and at pH 7 (92%). The maximum metal processing ability was determined at 250 mM arsenite/L (90%) while the minimum was estimated at 1250 mM arsenite/L (42%). The maximum arsenite removal ability of strain AS2 determined after 8 days was 68 and 82% from wastewater and distilled water, and the organism can be a good bioresource for green chemistry to eradicate environmental arsenite.
PubMed: 34841312
DOI: 10.1016/j.crmicr.2021.100020