Background: Breast milk is an important nutrient source for rapidly growing neonates since breastfeeding protects the newborn against some disease. This effect may be due to the useful and natural microflora of breast milk. Biosurfactants are unique amphipathic compounds produced by some microorganisms. The present study demonstrates the isolation and characterization of biosurfactant producing bacteria from human breast milk samples. Methods: The human breast milk samples were collected aseptically and then cultured in MRS agar media. The biosurfactant producing ability of the isolated strains was investigated by hemolytic assay, oil spreading method, drop collapse test and emulsification index assay. The screened isolates were identified by 16S rDNA gene sequencing analysis. In vitro antibacterial activities of biosurfactants against some Gram-positive and Gram negative bacteria were investigated by the agar disc diffusion method. This biosurfactant was characterized with Fourier transform infrared spectroscopy (FTIR). Results: In this study, 337 different colonies were isolated from 42 breast milk samples. The best isolates were identified as Pediococcus pentosaceus HM-1, Pediococcus pentosaceus HM-2 and Pediococcus pentosaceus HM-3 based on microscopic and 16S rDNA gene sequencing analysis. The biosurfactant extracted from screened strains exhibited a broad spectrum of antagonistic activity against some pathogenic bacteria. The results showed similarity to lipopeptide biosurfactants like surfactin. Conclusion: Bacterial strains isolated in this study could be valuable sources for novel biosurfactants. The Human breast milk could be a safe source for isolation of biosurfactant producing probiotic bacteria and for improve intestinal microflora of infants.
Studies on the isolation and molecular characterization of Lactobacillus spp. from human breast milk and assessment of their probiotic potential
