Published in Scientific Works. Series C. Veterinary Medicine, Vol. LXIII, Issue 2
Written by Alina NĂSĂLEAN, Emöke PALL, Andreea BUTA, Ştefana BÂLICI, Horea MATEI, Laurenţiu OGNEAN
The goat milk composition can be distinguished by significant proportions of biologically active proteins that can exert antimicrobial effects. In this context, the present work is focused on evaluating antimicrobial activity of total caseins in vitro, extracted from goat milk, concerning some reference bacterial strains such as Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853) and Staphylococcus aureus. The research was conducted on milk samples collected from two groups of clinically healthy goats, Carpathian (group I, n = 12) and Alpine (group II, n = 12) breeds. Milk samples were subjected to a procedure of total casein separation. In vitro test procedure consisted in evaluating the inhibitory effect of casein on the microbial strains listed, using the serial micro-dilution method in liquid broth, which led to the establishment of minimum inhibitory concentration (MIC), correlated with diffusion method. Thus, the concentrations tested were 10, 20, 30 and 40 mg casein / mL, and the interpretation was based on the measurement of the inhibition zones diameters. Our results indicate antimicrobial activity with variations dependent on the bacterial strain tested with no significant differences between the two goat breeds. Thereby, E. coli strain was proven to be very sensitive to all concentrations used, P. aeruginosa at the 20, 30 and 40 mg/mL concentrations, and the St. aureus to 30 and 40 mg casein/mL concentrations. Our results reveal the antimicrobial potential of milk proteins, analysing it in the current context of developing microbial resistance to antibiotics. In conclusion, caseins may be an alternative solution to diminish the consequences of the antibiotic resistance phenomenon, giving some dairy products the character of functional foods.
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