Characterization of Biosurfactant Produced by Probiotic Bacteria Isolated from Human Breast Milk

Introduction: Breast milk is an important nutrient source for rapidly growing neonates since breastfeeding protects newborns against a variety of diseases. 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 generating 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 rRNA gene sequencing. In vitro antibacterial activities of biosurfactants against a number of common bacterial strains were investigated by the agar disc diffusion method. This biosurfactant was characterized by Fouriertransform 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 HM1, P. pentosaceus HM2 and P. pentosaceus HM3 based on microscopic and 16S rRNA gene sequencing analysis. The biosurfactant extracted from screened strains exhibited a broad spectrum of antagonistic activity against some pathogenic bacteria. Conclusion: Bacterial strains isolated here can be valuable sources for novel biosurfactants. The Human breast milk is a safe source for obtaining biosurfactant producing probiotic bacteria and for improving gut microflora of infants.