The presence of (NRPS) and (PKS) genes at the deepsea hydrothermal field in the Aegean Sea

Deep-sea hydrothermal vents are characterized by extremely high concentrations of microorganisms in stark contrast to the surrounding sea bottom. Nevertheless, deepsea consumers do not rapidly remove the high biomass of prey from these communities maybe due to vent microbes’ chemical defenses which still remain largely unknown. Meanwhile, the detection of genes responsible for antimicrobial and cytotoxic activity such as non-ribosomal peptide synthases (NRPS) and polyketide (PKS) of deep-sea vent bacteria has not so far been attempted

PCR-based detection of mobile genetic elements in total community DNA

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The Kolumbo submarine volcano of Santorini island is a large pool of bacterial strains with antimicrobial activity

Microbes in hydrothermal vents with their unique secondary metabolism may represent an untapped potential source of new natural products. In this study, samples were collected from the hydrothermal field of Kolumbo submarine volcano in the Aegean Sea, in order to isolate bacteria with antimicrobial activity. Eight hundred and thirty-two aerobic heterotrophic bacteria were isolated and then differentiated through BOX-PCR analysis at the strain level into 230 genomic fingerprints, which were screened against 13 different type strains (pathogenic and nonpathogenic) of Gram-positive, Gram-negative bacteria and fungi. Forty-two out of 176 bioactive-producing genotypes (76 %) exhibited antimicrobial activity against at least four different type strains and were selected for 16S rDNA sequencing and screening for nonribosomal peptide (NRPS) and polyketide (PKS) synthases genes. The isolates were assigned to genus Bacillus and Proteobacteria, and 20 strains harbored either NRPS, PKS type I or both genes. This is the first report on the diversity of culturable mesophilic bacteria associated with antimicrobial activity from Kolumbo area; the extremely high proportion of antimicrobial-producing strains suggested that this unique environment may represent a potential reservoir of novel bioactive compounds

Efficacy and toxicity of orally administrated anti-coccidial drug treatment on Enteromyxum leei infections in sharpsnout seabream (Diplodus puntazzo C.)

Three drugs effective against myxosporeans and commonly used to treat spore-forming para- sites were tested in sharpsnout sea bream (Diplodus puntazzo) infected by Enteromyxum leei. Two medicated diets were applied, one containing salinomycin and amprolium and the second containing fumagillin. Compared to untreated fish, both treatments resulted in significant reduc- tions in prevalence, intensity of all developmental myxosporean stages, and mortality. The effect was more prominent with the salinomycin and amprolium combination, where the significant reductions in intensity, prevalence, and mortality were unaccompanied by any histopathological evidence of toxic side effects or growth reduction. Sporoblasts and mature spores with distorted structures were observed in both drug treatments, but were more prevalent in the salinomycin and amprolium treatment than in the fumagillin treatment, indicating direct effectiveness on the parasite. Salinomycin with amprolium is a promising treatment for myxosporean infections in intensively cultured warmwater fish, leading to parasite elimination

Rickettsia-like organisms (R.L.O.) infections of fin-fish [Ρικέχσιες και μικροοργανισμοί προσομοιάζονχες με ρικέχσιες (R.L.O.) οε εκχρεφόμενα ψάρια]

Rickettsia-like organisms (R.L.O.) infections of finfish have been reported in several salmonid and non-salmonid species in both fresh and seawater since 1939. This organism was not considered of economical importance to the global fin-fish aquaculture industry until Piscirickettsia salmonis was confirmed as the etiology agent of mass mortalities in the Chile during the 1990's. All cultured salmonid species can be infected by this intracellular bacteria and in diseased fish it may provoke a systemic response affecting most internal organs, but preferentially targeting the liver. For other R.L.O's the pathology may vary depending on both the imunogenicity of the R.L.O. and the species offish affected; eg, R.L.O. infections of the Hawaiian tilapia result in a systemic granulomatous inflammatory response. Initial published reports on R.L.O's affecting cultured juvenile sea bass (Dicentrarchus labrax) were described from sea-cages, at rearing temperatures ranging from 12-15°C, in the Mediterranean off the coast of France. In this outbreak the reported pathology was restricted to the mesencephalic regions of the brain. Subsequendy, the organism was identified from cultured sea bass of the coast of Greece, with moribund fish showing similar pathology; i.e brain, olfactory nerve and internal organs inflammation. These samples were preliminarily screened by immunohistochemistry and found to cross react with antisera to P. salmonis. This finding was also confirmed by demonstrating antigenic similarities between P. salmonis and European sea bass R.L.O. isolates from Greece. Recendy, a systemic type of the disease was demonstrated by histopathology in juvenile cultured juvenile sea bass. The meningitis, as well as other internal lesions affecting sea bass, is nearly identical to that seen in for R.L.O. infected Adantic salmon from British Columbia, Canada. Similar lesions have been noted for piscirickettsiosis in both Chilean and Eastern Canadian outbreaks: i.e liver, pancreas, retina, brain stem, meninges and the lamina propria of intestine © 2017. Journal of the Hellenic Veterinary Medical Society.All Rights Reserve

The Effect of Seasonality on the Health and Growth of a Newly Recorded Myxobolus Species Infecting Cultured Sharp Snout Seabream (Diplodus puntazzo C.)

The prevalence, intensity, and pathology of a Myxobolus sp. affecting the kidneys of cultured Diplodus puntazzo C. during the period 2003-2005 are described. The study included data collected from the largest farm in southern Greece where a high rate of mortality due to myxosporean infection occurred. Sharp snout seabream reared in sea cages in southern Greece underwent microbiological, parasitological, and histological examinations, while measurement and identification of parasites was performed immediately after sampling. Samplings were made daily from winter 2003 to autumn 2005. Prevalence was estimated for each season (autumn, winter, spring, and summer) each year (2003, 2004, and 2005). The Myxobolus sp. was detected in high numbers and with a high prevalence of infection in the renal interstitial tissue, especially during the summer months. The growth rate of infected D. puntazzo was very slow during the study period in comparison to cultured Sparus aurata L. and uninfected D. puntazzo