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Aims: We performed in silico analysis of CRISPRcas loci from Tenacibaculum maritimum, evaluated spoligotyping as a subtyping method and genotyped uncharacterized Turkish isolates from European sea bass by multilocus sequence typing (MLST). Methods and Results: Spoligotyping was performed with primers designed to allow amplification and sequencing of whole CRISPR‐arrays from 23 T. maritimum isolates. Twenty‐three completed/draft genomes were also downloaded from the NCBI database and analysed. MLST of Turkish isolates was achieved with a well‐established 7‐gene scheme. Tenacibaculum maritimum genomes carry a structurally complete but partially defective class II CRISPRcas locus due to known amino acid substitutions in encoded Cas9 proteins. Our spacer identification suggests that the host range of bacteriophage P2559Y and Vibrio phage nt‐1 include T. maritimum and that the most recurrent infection recorded by isolates has been with Tenacibaculum phage PTm5. Thirty‐eight isolates with this CRISPRcas locus belonged to 25 spoligotypes and to 24 sequence types by MLST, respectively. According to MLST, T. maritimum isolates from Turkey are most related to previously defined sequence types ST3, ST40 and ST41 isolates from Spain, Malta and France. Conclusions: The evaluated spoligotyping offers discriminatory power comparable to MLST. Significance and Impact of the Study: Spoligotyping has potential as a quick, easy and cheap tool for subtyping of T. maritimum isolates. [ABSTRACT FROM AUTHOR]

About 100 moribund rainbow trout fry (2-3 g) were brought to the laboratory for examination after an epizootic of citrobacteriosis on a farm in Bursa Province, northwest Turkey, in late March 2012. The dominant bacterium was identified by biochemical, API 20E, and VITEK II rapid tests. Colonies grown on xylose lysine deoxycholate (XLD) agar were yellow with an intensive yellow center and a surrounding zone of yellow precipitation. The fish displayed hyperemia of the mouth, dark color, bilateral exophthalmia, pale liver, and necrotic kidney symptoms. The possible etiologic agent was identified by 16S rRNA gene sequencing as Citrobacter braakii (GenBank accession number JX518488). Histopathological examination of the diseased fish revealed vacuolar degeneration in the liver epithelium, round and limited focal necrotic areas in the liver, desquamation in the intestine epithelium and glands that settled in the propria mucosa, and vacuolar degeneration of the intestinal epithelium. According to ATB VET and antibiogram disc diffusion, the isolated C. braakii strain was sensitive to apramycin, cefoperazone, chloramphenicol, colistin, gentamicin, nitrofurantoin, spectinomycin, and streptomycin but resistant to amoxicillin, amoxicillin/clavulanic acid, cefalotine, cotrimoxazole, enrofloxacin, erythromycin, florfenicol, flumequine, fusidic acid, kanamycin, lincomycin, metronidazole, neomycin, oxacilline, oxolinic acid, oxytetracycline, penicillin, pristinamycin, rifampicin, sulfamethizole, sulfamethoxazoletrimethoprim, tetracycline, and tylosin. We found the bacteria sensitive to 4 mg/l doxycycline in the ATB VET test strip but resistant to 30 μg/l doxycycline in the antibiogram disc diffusion test. [ABSTRACT FROM AUTHOR]

Purpose: Pinna nobilis (fan mussel) is one of the most important endemic bivalve molluscs in the Mediterranean and mass mortality events were observed in these mussels in recent years. In this study, we report mass mortalities caused by Haplosporidium pinnae , which has been spreading in the Mediterranean for 3 years, and reached the Çanakkale Strait, which is the entrance of the Marmara and the Black Sea., Material and Methods: Field observations during sampling and subsequent histopathological, biochemical, genetic, and microbiological analyses were carried out., Results: These analyses showed that H. pinnae infection spread among the natural beds of P. nobilis , causing severe tissue damage and oxidative stress. Our phylogenetic analyses suggested that the parasite spread through the Mediterranean much faster than thought. The results showed that vibriosis originating from Vibrio coralliilyticus , Vibrio tubiashii , Vibrio mediterranei , and Vibrio hispanicus , acted together with H. pinnae in infected individuals and caused death., Conclusion: It is highly probable that the spread of H. pinnae to the Sea of Marmara and the Black Sea may occur earlier than expected, and it was concluded that mass deaths were caused by co-infection with H. pinnae and a geographically specific marine pathogen that can infect P. nobilis populations.

Live-feed is indispensable to commercial fish larviculture. However, high bacterial loads in rotifers could pose a biosecurity risk. While this may be true, live-feed associated bacteria could also be beneficial to fish larvae through improved feed utilization or pathogen inhibition following host microbiota modification. The study objective was to elucidate the largely unexplored microbiota of rotifers propagated on five different diets through bacterial community profiling by 16S rRNA gene amplicon sequencing. Investigated rotifer samples had a median observed alpha-diversity of 338 ± 87 bacterial species. Alpha- and Gamma-Proteobacteria dominated the rotifer microbiota followed by members of classes Flavobacteriia, Cytophagia, Mollicutes, Phycisphaerae and Bacteroidia. Different diets significantly altered the bacterial communities associated with rotifers according to PERMANOVA test results and beta dispersion calculations. A common core rotifer microbiome included 31 bacterial species present in relative abundances over 0.01%. We discuss the functional role of some microbiome members. Our data suggested the presence of several known fish pathogens in stock rotifers. However, we found no evidence for increased loads of these presumptive taxa in propagated live-feed rotifers during this field trial., (© FEMS 2020.)

A new elastography method is presented that images the mechanical properties of soft tissue. The tissue is externally vibrated over a range of frequencies simultaneously and the resulting displacement is recorded at multiple locations and time instants with a sequence of ultrasound images. Two methods are proposed for estimating the mechanical properties from the recorded data. In the first method, equations of motion are written for a tissue model of masses, springs and dampers. The equations are solved to identify the model parameters and construct an image. The second method performs a transfer function analysis of the tissue motion. The tissue properties are identified from the shape the of transfer function. Simulations show good performance of the new method compared with static elastography. Initial experimental results from homogeneous and layered tissue phantoms also demonstrate the ability quantitatively to image tissue stiffness. Preliminary results are obtained for viscosity and density estimation. Further work is needed to extend the formulation to 3-D and improve robustness of the viscosity and density estimates.