Objective: The increase of multidrug resistance in bacteria has increased the efforts in search of alternative methods. The aim of the present study was to isolate and characterize the lytic phages and assess their lytic activity against a number of gram-negative bacteria. Materials and Methods: The phages and their respective hosts were isolated from wastewater collected from the municipal sewer system of Trabzon, Turkey. The lytic activities of phage were determined using the agar spot test. The identification and antibiotic susceptibility of host bacteria were determined using matrix-assisted laser desorption ionization time-of-flight mass spectrometry and Phoenix 100, respectively. The phages were characterized morphologically using transmission electron microscopy. One of the phages, Enteroc21, which has a broad-host-range, was further characterized by genome restriction endonuclease analysis and burst size. Results: Two phages infected strains of four different species, nine phages were able to infect 2-4 strains belonging to one or two species, and three phages showed lytic activity against only the hosts from which they were isolated. All phages belonged to the Siphoviridae, Myoviridae, and Podoviridae family based on trans- mission electron microscopy morphology. The Enteroc21 had more than 100 kb genome size and a burst size of 180 per infected cell. Most of the host strains were resistant to ampicillin, amoxicillin–clavulanic acid, and in particular, Achromobacter xylosoxidans TRAX 13 was multidrug-resistant showing resistance to cefepime, aztreonam, gentamicin, netilmicin, and ciprofloxacin. Conclusion: This study showed that the isolated phages have the potential to be used in phage therapy against various bacterial infections, including multidrug-resistant bacteria. Cite this article as: Khorshidtalab M, Durukan İ, Tufekci EF, Nas SS, Abdurrahman MA, Kiliç AO. Isolation and characterization of lytic bacteriophages from wastewater with phage therapy potentials against gram-negative bacteria. Eurasian J Med. 2022;54(2):157-164.

This study aimed to apply chitosan (CS) coating films enriched with Borago officinalis extract to preserve fresh rainbow trout fillets. Extracts of B. officinalis were prepared using ethyl acetate, ethanol, water, and an ethanol-water mixture. These extracts were incorporated into chitosan coating films at 0.5% and 1% (v/v) concentrations, and their antimicrobial activity and antioxidant abilities were investigated. CS films with borage extract in ethanol-water combination showed the highest antibacterial zone diameter (9.5 ± 2.1 mm) against Staphylococcus aureus. Based on its superior antimicrobial and antioxidant activity, the ethanol-water extract was selected for further film characterization, including moisture content, swelling degree, solubility, and color. The films were then tested for their effectiveness in preserving rainbow trout fillets stored at 7 ± 1 °C. The fish samples were divided into four groups: control, chitosan coating film, chitosan coating film with 0.5% B. officinalis extract, and chitosan coating film with 1% B. officinalis extract. Physicochemical, chemical, and microbiological analyses were conducted until fillet spoilage was observed (12 days). Results demonstrated that chitosan coating films enriched with 1% extract of B. officinalis prolonged the expiration date of the fish by six days, had significant antioxidant properties, and protected fish from discoloration. While the coating films demonstrated promising antioxidant properties and the shelf life extension of the fish samples by six days, further optimization will be required to enhance their antimicrobial effectiveness.

The genus Daphne presents great interest as a valuable source of natural agents in traditional medicine of various countries, including Turkey. In the current work, we investigated the phytochemical composition and biological properties of Daphne pontica L. extracts. Methanol extracts of roots, stems and leaves were prepared. The chemical characterization was performed by HPLC-ESI-MSⁿ, observing that flavonoids and phenolic acids were the main compounds. Biological properties were studied in terms of antimicrobial, DNA protection, anticancer, and enzyme inhibitory properties (cholinesterases, tyrosinase, amylase and glucosidase). Methanol extracts of roots, leaves, and stems of D. pontica had antimicrobial effects against a broad range of bacteria. In addition, methanol extract of roots of D. pontica exhibited a promising anticancer activity that was shown to be dose- and time-dependent for HeLa cells with an IC₅₀ value of 203.9 μg/mL. Generally, the leaf extracts exhibited the best enzyme inhibitory properties on the tested enzymes. According to our results, D. pontica might be regarded as a valuable source of natural agents to combat cancer, infectious diseases, and metabolic diseases. Graphical Abstract