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dc.contributor.supervisorMerrifield, Daniel
dc.contributor.authordo Vale Pereira, Gabriella
dc.contributor.otherSchool of Biological and Marine Sciencesen_US
dc.date.accessioned2018-06-08T15:17:35Z
dc.date.issued2018
dc.identifier10456585en_US
dc.identifier.urihttp://hdl.handle.net/10026.1/11629
dc.description.abstract

The pirarucu (Arapaima gigas) from Amazon basin is currently the largest farmed fish species and its production is increasing rapidly in Brazil. However, there is a concern about bacterial disease outbreaks and resulting mortalities in pirarucu farms. The use of probiotic bacteria as prophylactic method is recognized as beneficial practice to enhance fish production. The aim of this thesis was to isolate autochthonous probiotic strains from the pirarucu intestine, characterize their potential probiotic characteristics in vitro, and perform in vivo colonization and growth experiments. To this end, the intestinal microbial community of A. gigas was assessed at two different growth stages using high-throughput sequencing (HTS) analysis. Proteobacteria, Fusobacteria and Firmicutes were the most abundant phyla. At genus level Bradyrhizobium and Cetobacterium were the most abundant in adult and juvenile fish, respectively. In a further trial two isolated lactic acid bacteria (LAB): Lactococcus lactis subsp. lactis and Enterococcus faecium, showed in vitro suitability as probiotics. Two potential pathogens: Citrobacter freundii and Pseudomonas sp., were also isolated and their pathogenicity assessed. Subsequently, an in vivo experiment was performed to assess the potencial of LAB strains to colonise and modulate the gut microbiome of pirarucu after 21 days of feeding. The results showed a high abundance of Cetobacterium in all treatments. Additionally, both probiotic treatments decreased the levels of Clostridiales in pirarucu intestine and showed adherence to the fish mucosal tissue. Finally, a growth experiment was performed to assess the ability of to the candidate probiotics to improve growth parameters after 42 days of feeding. HTS confirmed that Cetobacterium was the most abundant genus in all treatments. Fish fed with L. lactis subsp. lactis presented higher percentage of increase (%I) of weight, specific growth rate (SGR), and monocytes in blood. The strain E. faecium interacted with the microbial gut community and was able to populate the mucosal tissue. In conclusion, both LAB strains presented probiotic characteristics and should be considered as probiotics in A. gigas farming. These probiotics could contribute to a reduction in antibiotics use in pirarucu farms, thus, adding value to the species as a sustainable aquaculture product.

en_US
dc.language.isoen
dc.publisherUniversity of Plymouth
dc.subjectMetagenomicsen_US
dc.subjectNutritionen_US
dc.subjectHealthen_US
dc.subjectAquacultureen_US
dc.subject.classificationPhDen_US
dc.titleDevelopment of probiotics for the sustainable cultivation of pirarucu, Arapaima gigasen_US
dc.typeThesis
plymouth.versionpublishableen_US
dc.identifier.doihttp://dx.doi.org/10.24382/916
dc.rights.embargodate2018-12-08T00:00:00Z
dc.rights.embargoperiod6 monthsen_US
dc.type.qualificationDoctorateen_US
rioxxterms.funderCoordenação de Aperfeiçoamento de Pessoal de Nível Superioren_US
rioxxterms.identifier.projectDevelopment of probiotics for the sustainable cultivation of pirarucu, Arapaima gigasen_US
rioxxterms.versionNA
plymouth.orcid_idhttps://orcid.org/0000-0003-1837-1726en_US


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