Selection and isolation of bacterium with probiotic potential from the Amazon ornamental fish Hypancistrus sp. (Siluriformes, Loricariidae)

Abstract

The aim of this study was to select autochthonous bacteria with probiotic potential from the gastrointestinal tract of King Tiger Pleco (Hypancistrus sp.) for future applications in captive production. For the isolation of lactic acid bacteria, 12 specimens (8.31 ± 0.28 cm and 12.60 ± 1.13 cm) were used, whose intestines were removed, macerated, and homogenized in sterile saline. A total of 21 strains were isolated from the intestinal tract on MRS agar, of which five strains (St1, St2, St3, St4, and St5) were selected for in-vitro tests. Three strains (St2, St3, and St5) showed the highest values of maximum growth per hour, with a final concentration of 109 CFU.mL^-1 in 24 hours. However, only the strains St3 and St5 had the highest growth (p<0.05) in the presence of NaCl (0.5 to 1.5%) and pH in the range of 5 and 6. For bile salts, the greatest resistance observed was for strain St5. In conclusion, this is the first report of the isolation of autochthonous bacteria for a Loricariidae, recommending the bacterium Enterococcus faecium as probiotic in the aquaculture creation of King Tiger Pleco.