Probiotic characteristics of the potential strain Lactobacillus acidophilus LA 304.17

Tóm tắt

For human use, probiotic bacteria need to be examined carefully both in vitro and in vivo. According to FAO/WHO recommendation for assessing probiotic bacteria, in our study the strain LA 304.17 was first examined for the in vitro requirements. In particular, the strain was identified as Lactobacillus acidophilus based on the morphological and biochemical characteristics as well as the nucleotide sequence of 16S rDNA. At pH 3 the survival rate of the strain were 51% and 71% for 3 hours and 1.5 hours, respectively and in the presence of 2% of bile salt for 48 hours its survival rate was 89.3%. In addition, the strain showed antibacterial activity against pathogens, including Escherichia coli VTCC 12272, Salmonella enterica VTCC 12277, Shingella flexneri VTCC 12060 and Bacillus cereus VTCC 11289. The strain produced β-galactosidase with the activity of 48 ± 0.29 (U/ml). The properties of the cell surface, including hydrophobicity properties (51.33 ± 2.46, 70.21 ± 5.84 and 19.63 ± 1.92 with xylen, chloroform and ethyl acetate, respectively), autoaggregation (the highest value of 36.8% after 5 hours) and coaggregation with the pathogens (the values of 17.2%, 18.1%, 18.7%, and 33.2% with E. coli VTCC 12272, S. enterica VTCC 12277, B. cereus VTCC 11289, and S. flexneri VTCC 12060, respectively), showed potentials to adhere to epithelial cells in gastrointestinal tract. Lastly, the strain was safe with regard to its hemolytic activity and antibiotic resistance. In general, the strain LA 304.17 possessed probiotic characteristics that met the in vitro requirements according FAO/WHO recommendation.