Schiff-base ligands containing phenanthroline terminals: Synthesis, characterization, biological activities and molecular docking study.

Three new phenanthroline-derived ligands were synthesized by the Schiff base condensation method. The first ligand was the result of 1,10-phenanthroline-2-carboxyaldehyde reaction with 1,4-diaminobutane (L1). The other ligands were obtained 1,6-diaminohexane (L2) and 1,8-diaminooctane (L3) with the phenanthroline aldehyde in separate reactions. The structures of all ligands were elucidated using spectral techniques such as FT-IR, 13C NMR, 1H NMR and LC ESI/MS. The geometric properties of ligands such as bond lengths, bond angles, dihedral angles, electronic properties, HOMO and LUMO energies were calculated by using the Gaussian 09w programme. Ligands were optimized with B3LYP and 6-311++G(2d,p) basis set and NMR and FT-IR spectra were calculated. Experimental and theoretical spectrum data were compared. All of the ligands showed antibacterial activity against Staphylococcus aureus ATCC 25923 and Bacillus cereus ATCC 11778. The anticancer activities of the ligands were also determined against human breast cancer (MCF7) and prostate cancer (DU145) cell lines. In addition, which conformation of the ligands was determined by the theoretical calculations. Docking studies of ligands with bovine serum albumin (BSA) were performed using Autock Tools 1.5.6 programme.

Antibiotic resistance and virulence genes in Enterococcus species isolated from raw and processed seafood.

This study evaluated the antibiotic resistance characteristics and virulence genes of enterococci isolated from raw and processed seafood sold in the Marmara Region, Turkey. In this context, the enterococcal load was determined as between 1.0 and 2.5 log CFU/g in 39 of a total of 397 samples. It was determined that 117 strains isolated from the samples belonged to Enterococcus gallinarum, E. casseliflavus, E. durans, E. faecium, and E. faecalis species. Erythromycin, tetracycline, streptomycin, and gentamicin resistance was observed, whereas the tetM, ermB, aac(6')-aph(2'')-la genes were found in a majority of the isolates. It was also determined that the isolates carried the agg2 and gelE virulence genes. When all these results are evaluated, the presence of these isolates in aquatic products may pose a risk in terms of food safety and public health.

Probiotic characteristics of bacteriocin-producing Enterococcus faecium strains isolated from human milk and colostrum.

As potential probiotic traits of human milk-isolated bacteria have increasingly been recognized, this study aimed to evaluate the probiotic properties of bacteriocin-producing Enterococcus faecium strains isolated from human milk and colostrum. Among 118 human milk- and colostrum-isolated lactic cocci, only 29 were identified as Enterococcus. Of these, only four Enterococcus faecium isolates exhibited bacteriocigenic activity against several pathogenic Gram-positive bacteria, including Listeria monocytogenes. These isolates exhibited high acid (up to pH 3.0) and bile tolerance (0.5% oxgall) in simulated gastrointestinal conditions, demonstrating their ability to survive through the upper gastrointestinal tract. All of the E. faecium strains were shown to be sensitive to most of the antibiotics including vancomycin, tetracycline, rifampicin, and erythromycin, while they were resistant to kanamycin and chloramphenicol. None of the strains showed any virulence (gelE, agg2, clyA, clyB, clyM) and antibiotic resistance genes (vanA, vanB, ermB, tetM, and aac(6')-le-aph(2″)-la). In addition, all the strains were able to assimilate cholesterol, ranging between 25.2-64.1% and they exhibited variable adherence (19-36%) to Caco-2 cells. Based on the overall results of this in vitro study, four of the E. faecium strains isolated from human milk and colostrum can be considered as promising probiotic candidates; however, further in vivo evaluations are required.

Microbiological quality of fresh-squeezed orange juice and efficacy of fruit surface decontamination methods in microbiological quality.

The aims of this study were to evaluate the microbiological quality of fresh-squeezed orange juice and to reduce the microbial population by using various chemical and physical fruit surface decontamination methods. In the first step of the study, polyethylene-bottled fresh-squeezed orange juice samples purchased in Ankara, Turkey, were examined. The average aerobic plate count (APC) and coliform count (CC) varied within the ranges of 3 to 5 log CFU/ml and 1 to 4 log MPN/ml, respectively. Ten of 60 samples contained various levels of Escherichia coli, while Salmonella spp. and E. coli O157:H7 were not detected in any of the samples. Comparing the efficacy of various fruit surface decontamination methods on microbial population of oranges, the best results were obtained following two applications of submersion in boiling water and 5% H(2)O(2) solution for both the uninoculated and inoculated samples. Orange juice samples obtained from surface-inoculated and decontaminated oranges were also examined. We showed that about 17.4% of the E. coli population was transferred to orange juice after extraction, indicating the separation of microbial contaminants from fruit peel during extraction. Finally, the levels of microbial contamination occurred throughout the extraction process on the inner surfaces of a commercial juice extractor at one of the sale points investigated. Significant (P < 0.05) increases in the APC and CC were determined in surface samples of the extractor after the extraction. Surface decontamination and extraction are critical steps in fresh juice production for preventing microbial contamination. Immersion in boiling water for 0.5 min, without using any chemicals, can be offered as an effective method to reduce microbial population on orange surfaces.