Effects of sage (Salvia officinalis) essential oil on growth, health and antioxidant capacity of common carp (Cyprinus carpio).

In the study, effects of S. officinalis essential oil on growth performance, health and antioxidant activity in C. carpio were investigated. The fish (13 ± 0.21 g) were fed with diet containing 1 and 3 ml kg- 1 of sage oil for 60 days. At the end of study, growth performance was not affected in fish fed with sage essential oil (p > 0.05). Superoxide dismutase (SOD) activity in hepatopancreas increased with addition of 1ml kg- 1 sage oil to the diet. However, Catalase (CAT) activity and malondialdehyde (MDA) values were not significantly altered in common carp. Total protein, albumin, glucose and hepatopancreas enzymes (aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP)) in blood serum were not affected by sage essential oil supplementation. At the histological examinations, no pathological findings were observed in hepatopancreas and intestine of carp. Goblet cells number and villi length in intestine increased with sage supplementation (p < 0.001). In addition, fertility, granulation and number of follicles increased in common carp fed with sage essential oil. Mortality after challenged with A. hydrophila was not observed in carp fed with 1ml kg- 1 concentration of sage essential oil. As a result, use of sage oil can be recommended in carp farming to improve gut health, provide disease resistance against A. hydrophila infection, and increase of fertility.

Identification of four autochthonous yeasts from the intestines of goldfish, Carassius auratus with potential probiotic properties and their effects on the most common fish bacterial pathogens.

In aquaculture, probiotic yeasts have gained particular interest because of their numerous health benefits for farmed fish. Many autochthonous yeasts have been isolated and identified from fish species with potential probiotic characteristics. In the present study, four autochthonous yeast strains were identified and characterized from the intestinal tracts of 16 healthy goldfish, Carassius auratus. Their in vitro probiotic properties were examined in terms of cell surface hydrophobicity, co-aggregation, and tolerability to different pH values and bile salt concentrations. These strains were identified by culture characters and sequence analysis of ITS (Internal Transcribed Spacer) gene regions. Four strains, namely Cutaneotrichosporon jirovecii isolate jpn01, Debaryomyces nepalensis isolate jpn02, Blastobotrys proliferans isolate jpn05, and Diutina catenulata isolate jpn06, were identified and added to the NCBI GenBank with accession numbers defined as MT584874.1, MT584873.1, MT649918.1, and MT501155.1, respectively. Results demonstrated the capability of these strains to co-aggregate with several fish-associated bacterial pathogens such as Lactococcus garvieae, Vagococcus salmoninarum, Vibrio anguillarum, Yersinia ruckeri, and Aeromonas hydrophila. Only the jpn05 strain did not co-aggregate with A. hydrophila. All identified yeast isolates could grow and tolerate low pH conditions (pH 2.0) and bile salt concentrations (up to 1.5%). Of interest, the hydrophobicity (%) of the yeast isolates was 80%, 94.0%, 80.6%, and 66.4% for jpn01, jpn02, jpn05, and jpn06 isolates, respectively. In this context, our data provide important in vitro evidence for the potential probiotic features of the yeast isolates. These strains could be considered candidate probiotic yeasts; however, their application in aquaculture nutrition necessitates further in vivo assays.

Ichthyobodo spp. Infection in Meagre (Argyrosomus regius) from Turkey: Parasitological and Pathological Findings.

OBJECTIVE: The aim of this study is to describe the first report of Ichthyobodo spp. infection in meagre (Argyrosomus regius) fry in a marine aquaculture facility in Turkey. METHODS: The material of the study was composed of 30 meagre A. regius in 2-3 g weight taken from the fry adaptation unit of a fish farm in the Aegean Sea. In this study, parasitological and pathological examinations were performed on the meagre. Ichthyobodo spp. was determined on the body surfaces and gills. RESULTS: Pathological examination revealed grayish mucous and erosions between the pin head and lentin over the skin of the examined specimens. Microscopic examinations revealed significant spongiosis, vacuolar degeneration, and hyperplasia in epidermal malpighian cells and hyperplasia in goblet cells. CONCLUSION: In the present study, Ichthyobodo spp. infection was for the first time determined in an alternative cultured meagre in Turkey.

[Detection of the first QnrS gene positivity in aquatic Aeromonas spp. isolates in Turkey]. / Türkiye'de su kaynakli Aeromonas spp. izolatlarinda saptanan ilk QnrS gen pozitifligi.

Aeromonas spp. are oxidase positive, gram-negative, facultative anaerobic bacilli that are widely distributed in aquatic environments. A.hydrophila, A.sobria and A.bestiarum may cause severe infections in both human and cold-blooded animals. Environmental persistance of quinolones that are widely used in both human and veterinary medicine plays an important role in the selection of resistant mutants. Plasmid-mediated resistance is one of the main mechanisms involved in quinolone resistance, and qnr, qepA, aac(6')-Ib-cr, oqxAB genes are identified as resistance determinants. Determination of various types of qnr gene in different bacteria mainly in Enterobacteriaceae, suggests that they are widely distributed in nature. Recently, plasmid-mediated quinolone resistance was defined among Aeromonas species isolated from water. The aim of this study was to investigate the presence of qnr genes among aquatic Aeromonas spp. in Turkey. A total of 45 Aeromonas strains isolated from water and fishes collected from three different geographical regions (Aegean, Mediterranean and Blacksea) in Turkey, were included in the study. The isolates were identified at species level by the use of 16S rDNA-RFLP (Restriction fragment length polymorphism) analysis and multiplex polymerase chain reaction (M-PCR). Among the isolates, 20 were identified as A.sobria, 10 as A.hydrophila, nine as A.salmonicida, four as A.bestiarum and two as A.veronii. The plasmid-mediated quinolone resistance determinants, qnrA, qnrB, qnrC and qnrS genes, were investigated by M-PCR, and sequence analysis was performed for nine qnr-positive isolates. According to the sequence analysis of the genes, qnr genes were characterized in six A.sobria, in two A.bestiarum and in one A.hydrophila isolate (9/45; 20%). When the sequence was compared with GenBank database, this gene was found as qnrS2. All qnrS-positive Aeromonas spp. isolates were ciprofloxacin-susceptible, while five of them were resistant to nalidixic acid. This study is the first research about the plasmid-mediated quinolone resistance and the presence of qnrS2 genes among Aeromonas spp. isolated from fishes and water in Turkey. In conclusion, various resistance genes of aquatic bacteria may constitute a potential risk for the transmission of those genes to other bacteria as well as clinical isolates.

Effect of ß-Mannanase and α-Galactosidase Supplementation to Soybean Meal Based Diets on Growth, Feed Efficiency and Nutrient Digestibility of Rainbow Trout, Oncorhynchus mykiss (Walbaum).

A 12-week feeding trial was conducted with 87 g rainbow trout to evaluate the effects on growth performances, feed efficiency and nutrient digestibility of adding ß-mannanase and α-galactosidase enzymes, solely or in combination. Seven diets were prepared by adding ß-mannanase, α-galactosidase and mixed enzyme at two different levels (1 g/kg and 2 g/kg) to control diet (without enzyme) including soybean meal. Mixed enzymes (1 g/kg, 2 g/kg) were prepared by adding ß-mannanase and α-galactosidase at the same doses (0.5+0.5 g/kg and 1+1 g/kg). At the end of the experiment, addition of ß-mannanase, α-galactosidase and mixed enzyme to diet containing 44% soybean meal had no significant effects on growth performance and gain:feed (p>0.05). In addition, adding ß-mannanase, α-galactosidase and mixed enzyme in different rations to trout diets had no affect on nutrient digestibility and body composition (p>0.05).