Marine aggregates in North Atlantic coast: Microbial characteristics and potential interactions with farmed Atlantic salmon (Salmo salar)

Microbial contamination of aggregates collected near an Atlantic salmon farm, in the Cherbourg roadstead, was followed monthly over one year to study the dynamics of Vibrio spp. and explore their impact on farmed fish. Salmon state of health was followed through blood and histopathological analyses. Vibrio were systematically found in aggregates with particularly high concentration in August. The Splendidus clade was strongly dominant in aggregates as well as in gills, and an increase in Vibrio diversity was observed in summer and autumn. Results did not demonstrate that aggregates directly impact the bacterial community of gills, but they suggested an aggregates-gills interaction. Gill contamination was correlated with water temperature and probably impacted by amoebae. Vibrio renipiscarius and Vibrio toranzoniae were isolated in North Atlantic for the first time. A better understanding of the interaction between marine aggregates, Vibrio spp. and fish is essential to improve salmon cage farming.

The occurrence of hemotropic Mycoplasma ovis-like species in horses

Hemotropic mycoplasmas (haemoplasmas) are wall-less bacteria, which may lead to anemia and, even, mortality in mammals. The present study was aimed to characterize the causative agent(s) of haemoplasma infection in blood samples taken from horses (n = 133) in south of Iran. Microscopic examination of blood smears and PCR assay were performed for the detection of hemotropic Mycoplasma and equine piroplasma (Babesia caballi and Theileria equi). For the purpose of molecular characterization, 16S rDNA and 18S rDNA markers were used for hemotropic Mycoplasma and piroplasma pathogens, respectively. The PCR-positive samples were sequenced for haemoplasma and further phylogenetic analysis was performed for the obtained haemoplasma sequences. Nine out of 133 (6.77 %, 95 % CI: 2.5-11.04 %) horses were positive for Mycoplasma sp. by PCR. Furthermore, three of these animals were co-infected with T. equi. Interestingly, the phylogenetic and molecular analysis of the haemoplasma sequences derived from the PCR amplicons in the equine positive cases showed 100 % identity with 16S rDNA in Mycoplasma ovis, an HM member mainly found in sheep and goats. In addition, the hematological analysis showed that PCR positive horses for M. ovis-like species had a lower hematocrit (Hct), hemoglobin (Hb) concentration, and red blood cell (RBC) count compared to the PCR negative ones (P ≤ 0.05). Mild anemia was also developed in the haemoplasma-positive horses. These findings represent the first molecular evidence of M. ovis-like species in horses. Further experimental studies are needed to examine the importance of this nonspecific host infection and evaluate its pathogenicity in equine and other species.