β-Glucosidase activity and antimicrobial properties of potentially probiotic autochthonous lactic cultures.

BACKGROUND

The demand for lactic acid bacteria products, especially probiotics, has increased. Bacteria that increase polyphenol bioavailability and act as bio preservatives are sought after. This study aims to identify autochthonous lactic acid cultures from EMBRAPA that demonstrate β-glucosidase activity and inhibitory effect on microbial sanitary indicators.

METHODS

Cell-free extracts were obtained by sonicating every 5 s for 40 min. The extracts were mixed with cellobiose and incubated at 50 °C. The reaction was stopped by immersing the tubes in boiling water. The GOD-POD reagent was added for spectrophotometer readings. Antimicrobial activity was tested against reference strains using the agar well diffusion method. Lactic cultures in MRS broth were added to 0.9 cm wells and incubated. The diameter of the inhibition zones was measured to determine the extension of inhibition.

RESULTS

Only EM1107 displayed extracellular β-glucosidase activity, while all autochthonous strains except CNPC020 demonstrated intracellular activity for this enzyme. CNPC003 had the highest values. On the other hand, CNPC020, similarly to CNPC007, exhibited notable inhibition against sanitary indicators. These two strains significantly differed from the other five autochthonous cultures regarding serovar Typhimurium ATCC 14028 inhibition ( < 0.05). However, they did not differ from at least one positive control in terms of inhibition against ATCC 25923 and ATCC 25922 ( > 0.05). Therefore, it is advisable to consider these cultures separately for different technological purposes, such as phenolics metabolism or bio preservative activity. This will facilitate appropriate selection based on each specific property required for the intended product development.