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    Evaluation of the Antimicrobial Effects of Olive Mill Wastewater Extract Against Food Spoiling/Poisoning, Fish-Pathogenic and Non-Pathogenic Microorganisms
    (Mdpi, 2024) Yilmaz, Dilek Kahraman; Kesbic, Fevziye Isil; Celik, Ekrem Sanver; Odabasi, Deniz Anil; Yılmaz, Sevdan; Abdel-Latif, Hany M. R.
    Although antibiotics are the main therapy for bacterial infections, the reports showed that the overuse (or misuse) of antibiotics will results in several problems such as the development of antibiotic-resistant strains, persistence of drug residues, and numerous environmental concerns. Therefore, finding antibiotic alternatives is considered of vital importance. Investigation of the antimicrobial properties of several plant substances and extracts is of great value to replace antibiotics. With this objective, this study aimed to evaluate the antimicrobial activities of an ethanolic extract prepared from olive mill wastewater (OMWW), which is a by-product of olive oil production with considerable environmental burden, against 38 bacterial strains, including fish-associated pathogens, non-pathogenic isolates, collection strains, and one yeast strain, Candida albicans. Disk diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal/fungicidal concentration (MBC/MFC) tests were used to determine the antimicrobial activity of the OMWWE. According to the results, OMWWE provoked strong inhibitory effects against Shewanella baltica strain SY-S145. It also showed a moderate inhibitory effect on Plesiomonas shigelloides strain SY-PS16 and Vibrio anguillarum strain SY-L24. The MIC and MBC of OMWWE on Shewanella baltica SY-S145, Vibrio gigantis strain C24, and V. anguillarum strain SY-L24 were 500 mu g/mL. The MIC and MBC on V. parahaemolyticus ATCC 17802 were 1000 mu g/mL, whereas the values for Aeromonas salmonicida ATCC 33658 were 500 mu g/mL and 1000 mu g/mL, respectively. To put it briefly, the OMWW extract showed high antimicrobial activity and can act as an environmentally friendly additive for the control and prevention of diseases caused by A. veronii, A. hydrophila, P. shigelloides, S. baltica, V. anguillarum, and V. parahaemolyticus. Its active agents also prevented infections of both fish-associated pathogens and food spoiling bacteria, which means it can not only help in the disease control mechanism but also in improving the safety of food by reduction of the microbial contamination.
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    Isolation, Identification, and Pathogenicity of Vibrio gigantis Retrieved from European Seabass (Dicentrarchus labrax) Farmed in Türkiye
    (Mdpi, 2023) Yılmaz, Sevdan; Karatas, Sueheyla; Steinum, Terje Marken; Guerkan, Mert; Yilmaz, Dilek Kahraman; Abdel-Latif, Hany M. R.
    In this study, V. gigantis strain C24 was isolated from cases of winter mortalities of hatchery-reared European seabass (Dicentrarchus labrax) broodstock in T & uuml;rkiye. The first mortalities were reported in September 2016 and occurred annually in early autumn/late winter until the end of February 2019, when 15% of accumulated mortality was recorded. Diseased moribund fish exhibited general septicemic signs, including dermal ulcerations with hemorrhagic margins, distended abdomens, and hemorrhages below the pectorals, pelvic fins, and at the operculum. Postmortem findings showed congestion in several internal organs, hemorrhagic ascitic fluid, and congested prolapsed anal openings. The representative bacterial isolate V. gigantis strain C24 was characterized as Gram-negative, motile, nitrite-producing, and as vibrio static agent O/129-sensitive. The full-length 16S rRNA sequence (Accession No. ON778781) and gyrB gene sequence (Accession No. ON792326) of the C24 strain showed high similarity to V. gigantis strains. Moreover, the whole-genome average nucleotide identity (ANI) values (ANI > 97.7%) against four V. gigantis strains above the species demarcation limit unambiguously identified the C24 isolate as a member of this species. A preliminary virulence-gene analysis showed that the V. gigantis isolate C24 encoded at least three exotoxins, including two aerolysins and a thermolabile hemolysin. The experimental infection showed that the C24 isolate exhibited low to moderate virulence in experimentally infected European seabass juveniles. Interestingly, antimicrobial susceptibility testing revealed that the C24 isolate was susceptible to nalidixic acid, ciprofloxacin, and several other antibiotics but resistant to tilmicosin, kanamycin, streptomycin, and ampicillin. To our knowledge, this study is the first to report that V. gigantis could be considered an emerging bacterial pathogen in T & uuml;rkiye, and it may threaten the international European seabass production.
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    Phenotypic and Genotypic Antibiotic Resistance of Staphylococcus warneri and Staphylococcus pasteuri Isolated from Stuffed Mussels
    (Istanbul Univ Press, Fac Aquatic Sciences, 2024) Yilmaz, Dilek Kahraman; Berik, Nermin
    This study aimed to assess the presence of Staphylococcus species in stuffed mussel samples sold in & Ccedil;anakkale province and to determine the antibiotic resistance of the isolates. A total of 246 stuffed mussel samples were examined, and two different Staphylococcus (S. warneri and S. pasteuri) were isolated from 12.19% of the samples. Among the Staphylococcus isolates, S. warneri was detected at a rate of 73.33% and S. pasteuri at 26.67%. Bacterial isolates (N=30) were examined for their resistance to amoxicillin/clavulanic acid (30 pg), ampicillin (10 mu g), erythromycin (15 pg), clindamycin (10 pg), vancomycin (30 pg), oxacillin (5 pg), tetracycline (30 pg), doxycycline hydrochloride (30 pg), chloramphenicol (30 pg), streptomycin (10 pg), gentamicin (10 pg), kanamycin (30 pg), nalidixic acid (30 pg), ciprofloxacin (5 pg), meropenem (10 pg), imipenem (10 pg), sulfamethox/ trimethoprim (25 pg), cefotaxime (30 pg), cephalothin (30 pg), ceftriaxone (30 pg), and levofloxacin (5 pg) antibiotics. Resistance to amoxicillin/clavulanic acid and erythromycin was found in all S. warneri isolates. In addition, all S. pasteuri isolates were found to be resistant to amoxicillin/ clavulanic acid. In S. warneri isolates, at least three resistance genes (BlaTEM, tetB-6, tetK-8) and up to eight resistance genes (BlaTEM, tetB-6, tetK-8, strA-strB, aphAI-IAB, ermC) were identified. All S. pasteuri isolates exhibited blaTEM, strA-strB, and aphAI-IAB resistance genes. In conclusion, it was determined that antibiotic-resistant S. warneri and/or S. pasteuri contaminates stuffed mussel samples. This study will serve as a valuable resource for enhancing monitoring strategies in stuffed mussel production. Further studies should be conducted to determine whether the products are suitable for food safety. Therefore, it is necessary to clarify the disease effects and mechanisms of the pathogens identified in stuffed mussels.
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    Sensory, Chemical and Microbiological Properties of Trout Sausage (Fermented Sucuk)
    (Istanbul Univ Press, Fac Aquatic Sciences, 2022) Yilmaz, Dilek Kahraman; Berik, Nermin
    This study aimed to produce fish sucuk using rainbow trout (Oncorhynchus mykiss) fillet and investigate its suitability for consumption. Sensory, nutrient composition, fatty acid and amino acid composition analyses were carried out in the sucuk prepared with a commercial spice mix. Total aerobic mesophilic bacteria, total coliform, total Enterobacteriaceae, Lactic acid bacteria, yeast and mould counts were found to be smaller than 1 log cfu g-1. It was found that the ratio of water, protein, fat, ash, total saturated FA, total mono-unsaturated FA and total poly-unsaturated FA were 48.63%, 17.27%, 22.00%, 2.52%, 50.17%, 43.23% and 6.6%, respectively. Glutamic acid (19.1 g 100 g(-1)), aspartic acid (17.17 g 100g(-1)), leucine (9.45 g 100 g(-1)) and lysine (8.05 g 100 g(-1)) were the main amino acids in fish sucuk. In addition, the sensory analysis results of the sucuk produced entirely from trout meat showed that it was acceptable. This study concluded that a sucuk product suitable for consumption could be produced using trout meat entirely, with the appropriate spice mixture, heat treatment and air conditions.