Antibacterial activity of donkey's milk against clinical isolate of Klebsiella pneumoniae

The purpose of this study was to investigate the antibacterial activity of raw donkey milk toward the clinical isolate of Klebsiella pneumoniae at 9, 15 and 38 degrees C as well as to clarify the role of lysozyme, lactoferrin and calcium content in the antibacterial activity of donkey's milk. The effects of contamination level and incubation period on this antibacterial activity were also examined. Antibacterial assays were performed by determing the bacterial count in intentionally contaminated (10(2), 10(3), 10(4) cfu/mL) donkey milk samples during 8 and 96 hours. Lab-on-a-chip electrophoresis and atomic absorption spectrometry were used for the determination of lysozyme, lactoferrin and calcium contents in donkey milk, respectively. The donkey milk samples showed varying degrees of antibacterial activity against the tested strain K. pneumoniae. The antibacterial synergism of lysozyme and lactoferrin was proven for this clinical strain as the samples with higher lactoferrin amount showed a stronger antibacterial activity. The correlation between calcium content and antibacterial activity of donkey milk samples was not established. Donkey milk showed stronger antibacterial potential at 15 degrees C compared to 9 degrees C, but this was limited by a higher growth rate of K. pneumoniae at 15 degrees C. The higher level of contamination resulted in a faster consumption of the antibacterial capacity of donkey milk. The artificial neural network model for prediction of K. pneumoniae count gave acurate fit to experimental data, showing a reasonably good (overall r(2) for donkey milk was 0.986, with training error 4.67.10(-4), while r(2) for nutrient broth was 0.982 and training error was 0.002).