Abstract

HERNANDEZ-GARCIA, Juan Emilio et al. In vitro evaluation of the probiotic potential of Lactobacillus acidophilus SS80 and Streptococcus thermophilus SS77. Rev Salud Anim. [online]. 2019, vol.41, n.1, e09.  Epub Apr 01, 2019. ISSN 0253-570X.

The objective of this work was to evaluate in vitro the probiotic properties of Lactobacillus acidophilus SS80 and Streptococcus thermophilus SS77 strains for animal use. Strains were characterized by biochemical tests, hemolysis, resistance to different pH, bile salt concentrations, microbial antagonism test against five animal pathogens, and auto-aggregation, co-aggregation and hydrophobicity tests. The results showed that both strains produce hydrogen peroxide, lipase and lecithinase. S. thermophilus SS77 was positive to casein proteolysis; however, the strains did not produce biogenic amines from the amino acids Lysine, Tyrosine and Tryptophan. In addition, S. thermophilus SS77 used alanine from 36 h on, whereas L. acidophilus SS80 used histidine from 72 h on. Both strains were negative to the hemolysis test and differed significantly in the pH values reached in skimmed milk powder after 2 h. They grew at pH 6.5 and 5.5 and resisted the simulated gastric juice for 3 h, with survival rates above 98 %. The strain of L. acidophilus SS80 grew only at 0.3 % bile (% w / v), while S. thermophilus SS77 did it at 0.3 %, 0 % and 1 % (% w / v). Growth inhibition occurred on all pathogenic strains evaluated, being Lactobacillus acidophilus SS80 more effective. Both strains were positive to the auto-aggregation, co-aggregation and hydrophobicity tests with values higher than 48 %. It is concluded that both strains have potential to be used as probiotic additives in animal feeding.

Keywords : zootechnical additive; lactic acid bacteria; Lactobacillus acidophilus SS80; probiotic; Streptococcus thermophilus SS77.

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