Use of water soluble extracts from ulva sp. by probiotics and fish bacterial pathogens

BACKGROUNDS The potential of seaweeds as dietary components is considered for a wide range of cultured fish species. In this context, Ulva is investigated as a good source of protein, minerals and vitamins. In addition, of probiotics are used to improve fish growth and modulate immune system and intestinal microbiota. To promote probiotics colonization and maintenance in the intestine, prebiotics are included in fish diets. Prebiotics are indigestible substrates used as energy sources for gastrointestinal microbiota, with a positive effect on the nutrition and health status of the host. In the present work, ability of selected probiotic and fish pathogen strains to use water soluble extracts from Ulva as nutrient source has been evaluated. MATERIALS AND METHODS Water-soluble extracts from Ulva sp. prepared by sonication of dehydrated samples were used to supplement minimum medium (M9). Probiotics and pathogens growth was evaluated based on the optical densities measured with a microplate reader. RESULTS AND CONCLUSIONS Probiotics were able to grow in minimum medium using water soluble extracts as nutrient source. On the other hand, P. damselae subsp. piscicida and V. harveyistrains were also able to grow with Ulvaextracts as nutrient source. However, incubation time to reach maximum growth was longer. Although Ulva extract may support growth of both probiotics and pathogen bacteria, faster growth of probiotics may help for the establishment of probiotic populations in the intestinal environment. In addition, beneficial effects on growth performance, gut microbiota, immunity and disease resistance of Ulva for Solea senegalensisare being studied. This work was funded by INIA, Ministerio de Economía y Competitividad and FEDER (RTA201400023 C0202).This work was funded by INIA, Ministerio de Economía y Competitividad and FEDER (RTA201400023 C0202).Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Use of in-vivo induced antigen technology to identify bacterial genes expressed during Solea senegalensis infection with Photobacterium damselae subsp. piscicida

The marine fish pathogen Photobacterium damselae subsp. piscicida (Phdp) is responsible for important disease outbreaks affecting several fish species including flatfish Solea senegalensis (Kaup). Phdp is able to avoid host defences by invasion and intracellular survival in non-phagocytic cells, mainly epithelial cells. Virulence factors reported in Phdp include restricting complement-mediated activity, apoptosis of phagocytes caused by exotoxins secretion, iron acquisition mechanisms such as siderophores that enable the pathogen to obtain iron from transferrin and ability to bind haemin and antioxidant enzymatic activities capable to counteract superoxide radicals (Do Vale et al., 2005; Andreoni and Magnano, 2014). Commonly, genes expressed during pathogen infection are important for pathogenicity. In vivo-induced antigen technology (IVIAT) (Handfield et al., 2000) has been used to identify in vivo-induced genes using pooled sera from fish that have experienced photobacteriosis. Materials and methods Sera were obtained from surviving S. senegalensis specimens after sublethal infection with Phdp (Lg41/01) and subsequently pooled and adsorbed against in vitro grown Phdp Lg41/01 and Escherichia coli BL21 (DE3) cells and lysates according to Handfield et al. (2000). The efficiency of sera adsorption was evaluated based on the immunoreactivity after each adsorption step with whole and lysed Phdp cells grown in vitro. A genomic expression library of Phdp Lg41/01 was generated in E. coli BL21 (DE3) using pET-30 expression system (Novagen, San Diego, CA, USA). The expression library was probed with adsorbed and non-absorbed sera using immunoblot technique. Reactive clones of in vivo-induced and in vitro antigens were obtained, purified and their inserted DNA sequenced (Macrogen Europe, Amsterdam, The Netherlands). Nucleotide sequences were compared against the NCBI protein database using BLASTx. Results A progressive reduction in sera immunoreactivity against in vitro grown Phdp cells was detected after the adsorption rounds, especially after the first adsorption step. Thus, following adsorption steps substantially removed antibodies against in vitro expressed antigens and resulted in relative enrichment in antibodies recognizing in vivo expressed antigens. The library from Phdp Lg14/01 constructed in E. coli BL21 (DE3) consisted of approximately 6500 recombinants. A total of 117 clones were selected for their reactivity with pooled adsorbed and non-adsorbed sera from convalescent S. senegalensis specimens after a first round of screening. In a second screening, 14 out of 117 candidate clones showed positive reaction, among which two clones were clearly positive and two gave weak reaction against adsorbed sera. Predicted proteins codified by inserted sequences have intracellular and membrane cell location and are involved in virulence, synthesis of intermediary products, energy metabolism and gene replication. Inosine-5’-monophosphate dehydrogenase (IMPDH) and alkyl hydroperoxide reductase (AhpC) have been identified as in vivo induced antigens expressed during S. senegalensis infection with Phdp. Iron/manganese superoxide dismutase (Fe/Mn-SOD) and alanyl-tRNA synthetase (AlaRS) proteins have also been identified, though with weak signal. Discussion and conclusion Identification of immunogenic bacterial proteins during Phdp infection is essential for understanding bacterial pathogenesis and development of effective vaccines. AhpC peroxidase activity has a protective role by reducing hydrogen peroxide, peroxynitrite and organic hydroperoxides. Immunization with AhpC conferred protection against Helicobacter pylori infection (O’Riordan et al., 2012). IMPDH catalyzes the conversion of products essential in de novo synthesis of guanine nucleotides. Adequate levels of purine nucleotides are critical for cell proliferation, nucleic acid replication, cell signaling and as a biochemical energy source. This gene is an important therapeutic target against bacterial diseases (Shu and Nair,2008). In conclusion, different genes expressed during Phdp infection in S. senegalensis have been identified. Among them, IMPDH and AhpC have been identified as in vivo induced antigens expressed during S. senegalensis infection with Phdp. Thus, they are likely to play a role in the virulence of Phdp. The antigenic character of these proteins makes them potential targets for the development of new vaccines. References Andreoni, F., and Magnani, M., 2014. Photobacteriosis: Prevention and Diagnosis. Journal of Immunology Research, 2014: 1-7. Do Vale, A., Silva, M.T., dos Santos, N.M., Nascimento, D.S., Reis Rodrigues, P., Costa Ramos, C., Ellis, A.E., and Azevedo, J.E., 2005. AIP56, a novel plasmid-encoded virulence factor of Photobacterium damselae subsp. piscicida with apoptogenic activity against sea bass macrophages and neutrophils. Molecular Microbiology, 58: 1025-1038. Handfield, M., Brady, L.J., Progulske-Fox, A., and Hillman, J.D., 2000. IVIAT: a novel method to identify microbial genes expressed specifically during human infections. Trends in Microbiology, 8: 336-339. O’Riordan A.A., Morales V.A., Mulligan L., Faheem N., Windle H.J., and Kelleher D.P., 2012. Alkyl hydroperoxide reductase: a candidate Helicobacter pylori vaccine. Vaccine, 30:3876-3884. Shu, Q., and Nair, V., 2008. Inosine monophosphate dehydrogenase (IMPDH) as a target in drug discovery. Medicinal Research Reviews, 28:219-232.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

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Detection of transposons modifying genome background in probiotics

The study of probiotic microorganisms is very interesting in the aquaculture field. Administration of live microorganisms in adequate amounts confers some benefits to the host (Kechagia et al. 2013). Even if Shewanella putrafaciens include pathogens and saprophytic strains related to fish spoilage and fish infection (Esteve, Merchán, and Alcaide 2016). The Pdp11 strain of Shewanella putrefaciens has been proved to provide beneficial effects in Sparus aurata (Chabrillón et al. 2005) and Solea senegalensis (Rodrigáñez et al. 2008). Studies focused on Pdp11 could hed light on the origin of this probiotic character. We have designed a bioinformatic workflow to detect transposons in the newly sequenced Pdp11 genome (Tapia-Paniagua et al, in press). Their presence interrupting genes account for a contribution to its probiotic character due to the lost of virulence or the gain of probiotic effect. The workflow was developed in Ruby programming language and provides: the genomic localisation of known transposons, host coding regions disrupted by complete transposons or their repeated insertion sequences, and transposons and coding regions disrupted identifiers, to stablish the putative functions of Pdp11 that could be affect by the transposons disruption. These results would support new possible hypothesis about the Pdp11 probiotic character since 14 coding regions related to S. putrefaciens were disrupted by transposons, 4 of which are directly involved in pathogenic mechanisms. This work was supported by co-funding by the European Union through the European Regional Development Fund (ERDF) 2014-2020 "Programa Operativo de Crecimiento Inteligente" together with Spanish AEI "Agencia Estatal de Investigación" to grants RTA2013-00068-C03, AGL2017-83370-C3-3-R and RTA2017-00054-C03-03.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Insights into the fecal microbiota of captive Iberian lynx (Lynx pardinus)

The Iberian lynx (Lynx pardinus) is an endangered species restricted to several areas of Spain and Portugal. Its low genetic diversity likely provokes immune depression and high susceptibility to infectious diseases. The intestinal microbiota is closely related to host health and nutrition. In order to contribute to the knowledge of the Iberian lynx intestinal microbiota, fecal microbiota of captive specimens from two breeding centers (“La Olivilla” and “El Acebuche”), located in Southern Spain, were studied by Denaturing Gradient Gel Electrophoresis (DGGE). Results grouped microbiota in two main clusters (I and III) which included DGGE patterns of 19 out of 36 specimens, cluster I being the most frequent in “La Olivilla” (50%) and cluster III in “El Acebuche” (55.55 %) specimens. Bacteroidetes, Firmicutes and Proteobacteria phyla were identified. Segregation of clusters I and III was attributed to different microorganism presence (Pseudomonas koreensis, Pseudomonas migulae, Carnobacterium sp., Arthrobacter, Robinsoniella peorensis and Ornithinibacillus sp.) and ability to use different carbon sources. Biolog EcoPlates® results indicate high functional diversity of fecal microbiota, it being higher in cluster III. The great impact of intestinal microbiota on host health supports the importance of its microbial composition understanding. This study is the first report of captive Iberian lynx fecal microbiota composition. [Int Microbiol 20(1): 31-41 (2017)]Keywords: Iberian lynx (Lynx pardinus) · fecal microbiota · biodiversit

The probiotic Shewanella putrefaciens PDP11 target virulence factors by modulating quorum sensing inhibition

Bacteria communicate with each other by producing signal molecules and regulating the production of virulence factors that have importance in pathogenicity. Quorum sensing (QS) is a bacterial communication mechanism based on the perception of population density and secretion of determining signal molecules called autoinducers (AI) such as the case of Acylhomoserine lactones (AHLs). AHLs-mediated QS processes seem to be common in the marine environment and among marine pathogenic bacteria, which pathogenesis could be mitigated by probiotics, among others. Probiotics are defined as live microbial cells that confer health benefits to the host and some of their mechanisms include the production of antagonistic compounds that are inhibitory toward pathogens. In this sense, Shewanella putrefaciens Pdp11, a strain described as a probiotic for use in aquaculture, has been analysed to mediate QS processes by quorum-quenching assays using synthetic AHLs. The enzymatic activity is estimated at around 80% and 30% for C8- and C10-HSL, respectively, while the rest of AHLs tested were not degraded by the Pdp11 strain. It would be an interesting feature of the probiotic Pdp11 strain since these AHLs are related to facilitating microbial adhesion by promoting biofilm formation among other virulence factors related to pathogens. On the other hand, a distinctive feature of AHL inactivated by lactonase is that it can be reactivated by acid treatment. In this way, little C8-AHL was recovered when it is extracted to pH2, which indicates the enzyme activity is not derived from the hydrolysis of the lactone ring derived from the action of lactonases, suggesting the enzyme activity in Pdp11 could be an AHL-acylase. The potential QQ activity of Pdp11 was unknown so, these preliminary studies led to a further as another promising probiotic QQ tool for aquaculture

The probiotic strain Shewanella putrefaciens Pdp11 strongly modulates gene expression of the fish pathogen Vibrio harveyi

In this work, the interaction between the fish probiotic Shewanella putrefaciens Pdp11 and the fish pathogen V. harveyi was studied by RNA-seq to understand how SpPdp11 interferes with the pathogen through bioinformatics analysis. Three types of cultures were performed: SpPdp11 alone, V. harveyi alone and SpPdp11 and V. harveyi together. RNA was extracted and sequenced (paired end, 2x75 bp) at the Ultrasequencing Service of the University of Málaga using the Illumina NextSeqTM 550 platform. Raw reads were processed using a bioinformatic pipeline and a network analysis was performed for the most relevant functional enrichment results. The results suggest that the presence of SpPdp11 affects V. harveyi to a greater extent than V. harveyi affects SpPdp11. Considering that V. harveyi is a pathogenic strain and SpPdp11 is a probiotic strain, this may be positive for its probiotic capacity, as it not only maintains its functionality almost intact, but also produces a huge imbalance in that of V. harveyiThis work was funded by project AG-2017-509 83370-C3-3-R (MINECO, Spain)

The effect of spray‐dried porcine plasma on gilthead seabream (Sparus aurata) intestinal microbiota

The effect of spray‐dried porcine plasma (SDPP) on the intestinal histological organization and autochthonous microbiota composition was evaluated in Sparus aurata. Fish were fed a basal diet (51 g/kg protein, 17 g/kg fat, 20.6 MJ/kg gross energy) and a diet containing 3 g/kg SDPP for 95 days (initial body weight, BW = 9.5 ± 0.2g, mean ± SD). The inclusion of SDPP promoted growth (p .05) between both groups. Intestinal microbiota was dominated by Proteobacteria (>85%) and Firmicutes (5%–12%), whereas Bacteroidetes never represented more than 1.5%. γ‐Proteobacteria, and Bacilli and Clostridia were the predominant classes. The short administration of SDPP (20 days) resulted in changes in microbiota diversity and richness associated with an increase in the sequences of the genus Lactobacillus and to a decrease in the genus Vibrio, whereas these changes were reverted at 95 days. Intestinal goblet cell density was not correlated to microbiota diversity and richness changes rather than to the immunostimulatory effect of the SDPP.info:eu-repo/semantics/acceptedVersio

Potential postbiotic activities of extracellular products of probiotic bacteria from gilthead seabream gastrointestinal tract

Probiotics have been established as a potential tool for improving gut health and environmental quality in aquaculture. However, recent evidence suggests that bacterial viability is not necessary to attain the beneficial-promoting effects. In this way, postbiotics have emerged providing a potential opportunity in the field of functional foods. They are soluble factors resulting from the metabolic activity of a probiotic or any released molecule, including short-chain fatty acids, enzymes, extracellular products, etc. that can have interesting properties inducing biological responses on health similar to probiotics while avoiding the administration of live microorganisms. Interestingly, its production can be affected by different factors such as the components of the culture media among others. Information on this type of postbiotic activities is very scarce, especially in the case of aquaculture, so the evaluation of the nutraceutical use of postbiotics to improve health management in fish and other cultivated aquatic organisms is an emerging area of research in aquaculture. In a previous work, we characterized four potential probiotics that were isolated from the gastrointestinal tract of Sparus aurata specimens fed with a diet containing a blend of microalgae. This diet involves a selection pressure on the intestinal microbiota of the fish that will be used to achieve enrichment in bacteria with a set of extracellular enzymatic activities capable of metabolizing and mobilizing the components of the diet enriched with microalgae. Here, we investigate the postbiotic potential of the extracellular products (ECPs) obtained from the four candidate probiotics grown on different microalgae-supplemented medium, and evaluate its enzymatic and antibacterial activity, and its cytotoxicity against the SAF-1 cell line. Our objective is to select different ECPs with a variety of activities that help the digestive process of seabream, with the aim to be included in aquafeeds.This work was funded by Junta de Andalucía (grant no. P20_00085) and co-financed by FEDER funds