Analysis of the probiotic and antioxidant potential of β-galactosidase-producing Lactobacilli

Abstract

The use of enzymes from bacterial metabolism allowed dairy products to reach the third part of the human diet in the group of functional nourishment or nutraceutical. In the wide range of this products are the probiotics: living microorganisms which provide several benefits to its host when given in adequate quantity. Therefore, the objective of this research is to select lactic bacteria producers of β- galactosidase and determine their probiotic and antioxidant characteristics through in vitro testing. After reactivating 75 strains collected in the collection of lactobacillus from the University of the West of Santa Catarina – UNOESC, 19 were selected based on the chromogen X-gal with higher capacity of enzymatic production. When determined the enzymatic activity on the substrate ONPG the strains 14, 8 and 39L were the ones with higher activity expressed in 24h with measurements of 0.044±0.003 U/mL, 0.066±0.003 U/mL, and 0.037±0.003 U/mL respectively. Concerning the survival in acid pH after 2h of incubation, the strain 8 presented feasibility of 13.5±2.96% in pH2 and, together with the strains 14, 8.1, and LB, presented viability in pH3 of circa 16%, 31%, 50.7% and 53% respectively. All the strains remained active in low concentrations of bile salts, varying from 75% in the concentration of 0.25% to 41% in the concentration of 0.5% and could inhibit at least three possible intestinal pathogens. The analysis of the test of hydrophobicity allowed us to conclude that the strain 14 had an activity of 27.93% of xylene adherence, on a par with the strain 25J with 29.95% of activity. Regarding the safety characteristics, none of the strain presented hemolytic activity. However, the strains 14, 8, 8.1, LB, and 39L presented resistance to the antimicrobial ciprofloxacin, and the strain 25J to ceftazidime, while the strains 8 and 39L showed a subpopulation resistant to the same antimicrobial and the strain 39L presented the same characteristic to penicillin. Observing the antioxidant characteristics, all strains had the same activity in the inhibition of DPPH radical, around 5.39±2.36% while presented satisfactory and variable inhibition of the auto-oxidation from ascorbate. In the present study, in general, all the isolates analyzed presented distinct benefits and it was not possible to determine only one culture for probiosis applications.