Obtaining protein hydrolyzates with antimicrobial activity from goat milk ́s whey

VARAS, R; ESPECHE, JC; RODRIGUEZ, S; HOLLMANN, A

Virtual

Congreso; XLIX Reunión Anual SAB; 2021

Sociedad Argentina de Biofisica

The present work aims to obtain antimicrobial hydrolyzates from goat ́s whey obtainedfrom a local cheese factory by means of enzymatic hydrolysis of the proteins present in it.For this, the goat's milk whey was pasteurized at 70 ° C, a process that caused theprecipitate to obtain a soluble and insoluble fraction. Both of them were then lyophilizedand stored at -20°C. The soluble fracción was analyzed by SDS-PAGE observing, asexpected, that major proteins present are α-lactoalbumin, β-lactoglobulin, andSericalbumin. To obtain antimicrobial peptides from this fraction, enzymatic digestionwith pepsin and rennet complex was performed. The results of SDS-PAGE demonstratedthat both enzymes achieved the hydrolysis of proteins into smaller peptides. Likewise, theBradford method was applied to determine the protein content in each of the samples.Assays were conducted to test the antimicrobial activity of the soluble fractionhydrolysates against Escherichia coli ATCC 25922 and Staphylococcus aureus. ATCC25923 The results show that the hydrolyzates were able to inhibit the microbial growth ofboth strains on agar plates at 3 and 4 hours of incubation. The whey soluble fractionhydrolyzed with pepsin proved to be more efficient especially against E. coli strain,reducing the microbial load after 4 h of incubation by 2.5 times, with respect to 1 timesreduction of the fraction with rennet. On the contrary, in the case of S. aureus, it was thefraction hydrolyzed with rennet that exhibited the highest antimicrobial activity with areduction of 3 times with respect to less than one time of pepsin hydrolyzate. In addition,the duplication time of each bacteria in those conditions was also obtained, observing thehigher effects in E. coli treated with the pepsin hydrolyzate with a duplication of this time.Afterward, by using ultrafiltration columns the peptides with less than 3000 KDa fromboth hydrolyzates (with Pepsine and Rennet complex) were purified, observing for bothultrafiltered hydrolyzates a significantly higher inhibitory activity confirming the presenceof active peptides with low molecular mass.Besides further experiments should be made to a better characterization, all these dataconfirm that whey goat milk is a good source for the obtention of antibacterial hydrolyzatepeptides that could be applied in food, as coming from a safe source, with the advantageof its low cost as it is already considered waste from cheese manufacturing.