Repository logo

DDI - Teses de doutoramento

Permanent URI for this collection

http://hdl.handle.net/10400.18/24

Browse

Browsing DDI - Teses de doutoramento by Subject "Agentes Microbianos e Ambiente"

Now showing 1 - 1 of 1
  • Decrypting the diversity of microbiome in aquaculture
    Publication . Salgueiro, Vanessa; Caniça, Manuela; Manageiro, Vera; Nogueira, Isabel
    Aquaculture can play an important role in reducing the overexploitation of natural re- sources and feeding the world’s growing population. However, the use of e.g., antibiotics in aquaculture can favor the development of resistant bacteria and jeopardize the safety of its products. Thus, this Ph.D. thesis aimed to contribute to the deciphering of aquaculture’s mi- crobiome and resistome, as well as to the understanding of the role of mobile genetic elements (MGE) in the dissemination of resistance genes in these environments. Several approaches were used, to obtain the results that most reflect the microbiome and resistome of seabream and bivalve mollusks from aquaculture. All microbiomes studied were very diverse, encompassing commensal and pathogenic bacteria from seabream and bivalve mollusks (e.g., Aeromonas,Kocuria, Pseudomonas and Vibrio genera), as well as bacteria important in human medicine (e.g., Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae). Twenty-one new se- quence types were described in Aeromonas spp., Citrobacter sp., Enterobacter spp., Shewanella spp., Staphylococcus sp. and Vibrio spp. Decreased susceptibilities to phenicols, oxytetracy- cline, β-lactams (namely carbapenems), quinolones, glycopeptides, mupirocin, erythromycin, and colistin were found. The resistome also revealed a great diversity of genes in all samples studied associated with antibiotics (e.g., blaTEM-1B, mecA, sul2, mcr-9.1), disinfectants (e.g.,formA-type), and heavy metals (e.g., sil) resistance. Twenty-five different genes related with increased virulence were also detected. Thirteen new β-lactams resistance genes were identi- fied (e.g., blaCTX-M-246, blaFOX-18, and blaOXA-958) and 35 other resistance genes, namely for antibi- otics (e.g., mcr-9 and qnrD2), heavy metals (e.g., emrA and mdtE) and disinfectants ( sitABCD- type), and virulence factors (e.g., astA and hlyF) were here described for the first time associated with aquaculture. Our results suggest that some of these resistance genes (e.g., erm(T)-type,qnrB19, catA1-type, tet(A), dfrA-type, aph(6)-Id, qacE∆ 1 and merA) are being disseminated by MGE such as plasmids, class 1 integrons, and Tn As1. These findings not only expand our knowledge about aquaculture’s microbiome and resistome, but also provide the necessary xiv information to implement the most suitable measures to control antibiotic resistance in aqua- culture environments.
    2023Doctoral thesis Open access Show more