Microbiota composition and intestinal integrity remain unaltered after the inclusion of hydrolysed Nannochloropsis gaditana in Sparus aurata diet

The use of lysed microalgae in the diet of carnivorous fish can increase the bioavailability of proteins and bioactive compounds, such as unsaturated fatty acids or vitamins in the digestive tract. These are essential molecules for the proper physiological development of fish in aquaculture. However, some antinutritional components and other undesirable molecules can be released from an excess of microalgae supplied, compromising the integrity of the intestine. The inclusion of small amounts of hydrolized microalgae in the fish diet can be a good strategy to avoid negative effects, improving the availability of beneficial compounds. Nannochloropsis gaditana is an interesting microalgae as it contains nutraceuticals. Previous studies reported beneficial effects after its inclusion in the diet of Sparus aurata, a widely cultured species in Europe and in all Mediterranean countries. However, administration of raw microalgae can produce intestinal inflammation, increased intestinal permeability, bacterial translocation and disturbance of digestion and absorption processes. The aim of this study was to evaluate changes in the intestinal microbiota and barrier stability of S. aurata fed with low inclusion (5%) hydrolysed N. gaditana. Intestinal microbiota was analyzed using Illumina MiSeq technology and libraries were constructed using variable regions V3-V4 of 16S rDNA molecules. Analysis were based in the identification, quantification and comparison of sequences. The predictive intestinal microbial functionality was analyzed with PICRUSt software. The results determined that the intestinal microbiota bacterial composition and the predictive intestinal microbiota functionality did not change statistically after the inclusion of N. gaditana on the diet. The study of gene expression showed that genes involved in intestinal permeability and integrity were not altered in fish treated with the experimental diet. The potential functionality and bacterial taxonomic composition of the intestinal microbiota, and the expression of integrity and permeability genes in the intestine of the carnivorous fish S. aurata were not affected by the inclusion of hydrolysed 5% N. gaditana microalgae

Probiotic supplementation influences the diversity of the intestinal microbiota during early stages of farmed Senegalese sole (Solea senegalensis, Kaup, 1858)

Ingestion of bacteria at early stages results in establishment of a primary intestinal microbiota which likely undergoes several stages along fish life. The role of this intestinal microbiota regulating body functions is crucial for larval development. Probiotics have been proved to modulate this microbiota and exert antagonistic effects against fish pathogens. In the present study, we aimed to determine bacterial diversity along different developmental stages of farmed Senegalese sole (Solea senegalensis) after feeding probiotic (Shewanella putrefaciens Pdp11) supplemented diet for a short period (10–30 days after hatching, DAH). Intestinal lumen contents of sole larvae fed control and probiotic diets were collected at 23, 56, 87, and 119 DAH and DNA was amplified using 16S rDNA bacterial domain-specific primers. Amplicons obtained were separated by denaturing gradient gel electrophoresis (DGGE), cloned, and resulting sequences compared to sequences in GenBank. Results suggest that Shewanella putrefaciens Pdp11 induces a modulation of the dominant bacterial taxa of the intestinal microbiota from 23 DAH. DGGE patterns of larvae fed the probiotic diet showed a core of bands related to Lactobacillus helveticus, Pseudomonas acephalitica, Vibrio parahaemolyticus,and Shewanella genus, together with increased Vibri o genus presence. In addition, decreased number of clones related to Photobacterium damselae subsp piscicida at 23 and 56 DAH was observed in probiotic-fed larvae. A band corresponding to Shewanella putrefaciens Pdp11 was sequenced as predominant from 23 to 119 DAH samples, confirming the colonization by the probiotics. Microbiota modulation obtained via probiotics addition emerges as an effective tool to improve Solea senegalensis larviculture.En prens

Intraspecific characterization of Vibrio alginolyticus isolates recovered from cultured fish in Spain

Aims: Intraspecific differentiation and characterization of Vibrio alginolyticus strains isolated from cultured fish in Spain. Materials and Results: Thirty-four Vibrio alginolyticus strains isolated from cultured fish were intraspecifically characterized on the basis of biochemical and exoenzymatic patterns, outer membrane protein (OMP) profiles, ribotyping and plasmid analyses. The typing methods used did not allow to group V. alginolyticus isolates on the basis of their sources of collection. A higher homogeneity was observed in OMP profiles. A high percentage of isolates were plasmidless. Ribotyping was the highest discriminatory typing method, as all the isolates tested presented 23 profiles using the HindIII restriction enzyme. On the basis of the ribotyping pattern, a similarity matrix and a dendrogram were constructed. Conclusions: The results obtained indicate that V. alginolyticus strains isolated from southwestern Spain belong to different clonal lineages. Significance and impact of the study: This study has shown differences with other similar studies carried out in other areas of Europe with strains of V. alginolyticus with respect to the clonal lineages of the strains isolated in southwestern Spain

Probiotic Shewanella putrefaciens (SpPdp11) as a fish health modulator: A review

©. This manuscript version is made available under the CC-BY 4.0 license http://creativecommons.org/licenses/by/4.0/ This document is the Published Manuscript version of a Published Work that appeared in final form in [mICROORGANISMS]. To access the final edited and published work see [10.3390/microorganisms8121990

JFD157 1..9999

The first description of pasteurellosis affecting sole, Solea senegalensis (Kaup), cultured in the South-west of Spain is reported. Diseased fish showed no apparent lesions except for a dark skin pigmentation and swelling in the abdominal cavity. Internally, affected specimens showed paleness of liver and kidney and typical white tubercles of 1±2 mm in diameter in the spleen. Microbiological analysis of these fish revealed the presence, in pure culture from all the organs examined, of one type of bacterial colony which was biochemically and serologically characterized as Photobacterium damsela ssp. piscicida. The sensitivity pattern to antimicrobials and the enzymatic activities of the bacterial extracellular products are described

Modified most-probable-number technique for the specific determination of Escherichia coli from environmental samples using a fluorogenic method

A specific and senstive modification of the most-probable-number (MPN) technique by addition of 4-methylumbelliferyl-β-D-glucuronide (MUG) to both presumptive and confirmatory media was performed. The use of this modification allows the precise determination of Escherichia coli from marine samples (seawater, sediment and shellfish) within 7 days compared to 10–12 days required by using of the standard methodology. No false-positive isolates for fluorescence reaction have been observed, although one E. coli strain fluorescent-positive on agar was isolated from nonfluorescent tubes. Klebsiella pneumoniae was the species most frequently detected from tubes with gas and fluorescence production and typical morphology on mFC agar, but failed on nutrient-MUG agar. Using a unifactorial variance analysis of the mean, fluorescence in tube and on agar has been determined as the factor which allows the detection of E. coli presence in the three sample types with high accuracy. The incorporation of MUG to the selective broth in the confirmatory test has been shown to avoid false-positive results due to shellfish tissue β-glucuronidase activity