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In this study, chemical compositions and in vitro antibacterial activities the components of essential oils and extracts of sage (Salvia officinalis L.), rosemary oil (Rosmarinus officinalis L.), lavandin (Lavandula x intermedia var. Super), and hyssop (Hyssopus officinalis L.) against fish pathogens: Gram-negative bacteria (Aeromonas caviae, Aeromonas hydrophila, Vibrio anguillarum, Yersinia ruckeri, Edwardsiella tarda, Pseudomonas aeruginosa) and Gram-positive bacteria (Lactococcus garvieae, Staphylococcus warneri, Vagacoccus salmoninarum) were investigated with Well Diffusion Agar assay. The composition of the essential oils and extracts were analyzed with GC/MS and HPLC, respectively. A total of 42 components in sage, 39 in rosemary, 44 in lavender, and 46 in hyssop were detected. As a result of this study, the sage and rosemary oils exhibited a broad-spectrum inhibitory effect (a strong antibacterial effect against Gram (+) and Gram (-) pathogens). Lavandin oil also showed a strong antibacterial effect against a majority of pathogens. The spectrum of inhibitory activity of hyssop oil was found narrower than other plant oils. In further studies, in vivo antibacterial effects of sage, rosemary and lavandin essential oils should be investigated.

WOS: 000390600600002 In this study, we isolated Chryseobacterium sp. from koi in Turkey. The disease outbreak occurred in fish weighing 10-300g (water temperature 9-10 degrees C) in November 2011-February 2012. The cumulative mortality rate was approximately 55% over 4 months. Infected koi exhibited anorexia, weakness, emaciation, damage to dorsal and caudal fins, grey-white skin discoloration (1-1.5cm) in the head area, large open wounds in skin with disease progression, necropsy findings, paleness of the liver, enlarged spleen and kidney, acidic fluid in the body cavity. Samples for bacteriological examinations were collected from the kidney, liver, and spleen using sterile swabs; these samples were streaked onto Anacker ordal Agar and incubated at 18 degrees C for 48 h. Five bacterial isolates were obtained from diseased fish. Phenotypic characteristics of the isolates were determined by conventional methods and rapid identification kits, API 20NE, and API ZYM. Comparative 16S rRNA gene sequence analysis demonstrated that isolate Sin57 belonged to the genus Chryseobacterium, with highest sequence similarity (98.5%) to C. aahli T68(T) and C. limigenitum SUR2.

The effectiveness of vaccine mixtures against lactococcosis was tested in rainbow trout (Oncorhynchus mykiss). The M1 strain of Lactococcus garvieae, isolated from a recent outbreak of lactococcosis at a rainbow trout farm in Turkey, was used in a trial comparing five immuniza- tion treatments: (a) formalin inactivated bacterin (vaccine), (b) the above bacterin together with Freund’s Incomplete Adjuvant (FIA), (c) the bacterin combined with β-glucan, (d) β-glucan only, and (e) phosphate buffered saline-PBS (control). Fish were given intrapritoneal injections and challenged by exposure to the bacteria 30, 75, or 125 days after vaccination. In fish exposed to the bacteria 30 days after injection, the relative percent survival (RPS) was 88.89% in the group that received only bacterin and 100% in the group that received the bacterin combined with FIA. Immunity remained high in the bacterin+FIA group, as the RPS in this group remained 100% in fish challenged at 75 days, significantly higher than in all other groups. In fish exposed to the bacteria 125 days after vaccination, the RPS was 54.55% in fish vaccinated with the bacterin only and 84.84% in fish vaccinated with bacterin+FIA. In the group that received only β-glucan, immunity did not improve after vaccination. Micro-agglutination tests of serums showed that immunized fish produced antibodies at high titers within 30 days. In short, the formalin-inacti- vated M1 strain provided longer lasting protection against Lactococcus garvieae in rainbow trout when combined with FIA than when administered alone or with β-glucan.

Aerobic bacterial flora in the intestines of seabream (Sparus aurata) larvae and juveniles, in diets they were fed (rotifers, brine shrimp, artificial diet), and in their rearing water were analyzed. Fish fed live feeds had a higher bacterial count than the fish fed the artificial diet. In rotifers, the total bacteria count was 8.7 x 106 and Pseudomonas dominated the flora (60.2%). In larvae fed rotifers, the bacteria count was 9.8 x 102, with Pseudomonas (48.4%) and Vibrio (28.3%) domi- nating. In brine shrimp, the bacterial count was 1.7-3.5 x 107 cfu/g and Vibrio (73.7-81.3%) was more prevalent than Pseudomonas (10.2-15.5%). In larvae fed brine shrimp, the bacterial count was 5.3 x 104-1.8 x 105 and Vibrio (61.2-70.1%) dominated. The count for the artificial feed was 1.2 x 104 with Pseudomonas slightly dominating while for juveniles fed artificial feed the count was 2.3 x 104, with Vibrio slightly dominating. Bacterial microflora in the rearing water ranged from 1.3 x 102 to 3.2 x 103 cfu/ml. The study showed that the microflora of fish feeds quantita- tively and qualitatively affect the intestinal microflora of seabream larvae and juveniles.