Abstract: The Lactobacillus composition of breast milk samples from Uygur mothers at different stages of lactation in Kashi, Xinjiang was comparatively investigated by strain isolation using modified MRS medium, repetitive polymerase chain reaction (rep-PCR) fingerprinting, homology analysis of the 16S rRNA sequence, and construction of a phylogenetic tree by means of MEGA V5.0. The results showed that a total of 229 Lactobacillus strains were isolated from 45 breast milk samples and they were identified as Lactobacillus, Enterococcus and Streptococcus, respectively. Of these isolates, 96.1% belonged to Lactobacillus spp., including L. brevis (75 strains), L. fermentum (82 strains), L. ori (37 strains), L. vaginalis (4 strains) and L. gasseri (22 strains). L. vaginalis is a rare bacterial species. The obtained data showed that the composition of Lactobacillus in the breast milk samples was diverse and varied among lactation stages. The population structure of Lactobacillus in mature milk samples was more complex than that of colostrum and late milk, and it was the most complex in breast milk samples between day 5 and month 5. This study provides the basis for the development of probiotics resources from breast milk.

Key words: Lactobacillus, breast milk, population, diversity, fingerprint