Isolamento, cultivo e identificação de bactérias com potencial uso probiótico no cultivo de organismos aquáticos: Estudo de caso com bactérias do trato gastrointestinal do linguado Paralichthys orbignyanus (Valenciennes, 1839).

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Probiotic organisms are those capable to improve the health of their hosts, by assisting in the food digestion and nutrient assimilation, stimulating their immunological system or by controlling the development of pathogens. However, the use of commercial probiotics poses a serious hazard to the health of farmed animals and to the environment that must be considered. Bacteria present in such commercial products might have resistance genes to antibiotics that can be transferred to pathogenic microrganisms in the culture environment. The screening for strains isolated from the host itself would be an alternative for this issue. The aim of this work was to isolate, culture and identify native bacteria with putative use as probiotic in the rearing of aquatic animals. In the present work bacteria were obtained from the gastrointestinal tract of a laboratory-reared flounder Paralichthys orbignyanus (Valenciennes, 1839) reared at the Marine Aquaculture Station of the Federal University of Rio Grande - FURG. Serial dilutions from the gastrointestinal tract were seeded in plates with four culture mediums (TCBS, MRSA, MA and NA), incubated and the growing colonies were isolated and purified. Low values of CFU (104) were probably due to the long time taken from sampling to analysis or due to transporting conditions. Despite of it, 94 strains, present in eight different colony morphotypes, were recovered. The genomic DNA of 46 strains isolated from the TCBS and MRSA mediums were extracted, amplified, purified and the gene coding the 16S rRNA region was sequenced. The bacteria were clustered and identified by the construction of phenograms. The results showed the presence of four genera, Brachybacterium, Brevibacterium, Photobacterium and Staphylococcus. Nineteen of the isolates clustered with none of the existing typestrain, suggesting that they might be species not previously described. Future perspectives of this work are the setting up of in vitro and in vivo tests in order to define the probiotic potential of the isolated strains by improving the growth performance of P. orbignyanus or inhibiting the development of pathogens. Beside that we intend to isolate probiotic micoorganisms from other laboratory-reared aquatic organisms.

ASSUNTO(S)

paralichthys orbignyanus cultivo aquicultura probiótico bactérias isolamento

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