The Composition Of Branched-chain Fatty Acids In Preterm Human Breast Milk And Their Anti-biofilm Activity

Branched-Chain Fatty Acids(BCFAs)are a type of fatty acid that carbon chain with one or more branched chains.BCFAs are also important nutrients accumulated in the intestinal tract of infants before birth,have protective effects on the intestinal mucosa and inhibit the formation of biofilms by pathogenic bacteria.The intestinal development of preterm infants is incomplete,and human breast milk-derived BCFAs can provide important protection.The current research on BCFAs of human breast milk is still very few,especially for preterm infants.There are few reports on the related research on level of different BCFAs in human breast milk of preterm infants,their distribution in triglyceride natural source and function.Therefore,this thesis mainly studied the composition and distribution of BCFAs in human milk fat,especially breast milk from preterm infant's mother.The effects of gestational age,lactation time,diet,and nursing motherhood on BCFAs content in human breast milk and its location distribution were investigated.The distribution of BCFAs in vernix and meconium was compared,and then the inhibitory effect of BCFAs isolated from lanolin on microbial biofilms was studied using the C.violaceum and intestinal pathogens as bacterial models.The main contents of this paper were as follows:Firstly,human breast milk from preterm infants mothers were used as a raw material,and the total BCFA composition was measured after seperation using a thin layer of urea and silver ion enrichment method established.The results showed that BCFAs in these samples reached 19.42%,lower than that of term infants.Most of methyl BCFAs were common terminal methyl groups,and their carbon chain length is C12~C22.GC-MS was further used to determine the common monomethyl BCFAs which revealed existence of iso-C14:0,iso-C15:0,anteiso-C15:0,iso-C16:0,iso-C17:0,and anteiso-C17:0.The max and min concentration was 0.55% and 0.27%,respectively,of which anteiso-17:0 is the most abundant one in all samples.Secondly,all samples were grouped according information of donors including gestational age,lactation,diet and lactation.Results show that relative percentage of BCFAs were significantly different across lactation stages,which was enriched in colostrum,followed by transitional and mature human breast milk(median: 0.41,0.31,and 0.28%,respectively,p < 0.05).Lower BCFAs in preterm human breast milk compared to term human breast milk may have been related to maternal intake.BCFAs were mainly in the sn-2 position(52%~65%),similar to palmitic acid.Overall,preterm and term human breast milk BCFAs were similar and showed specific concentration patterns,resembling 16:0 with respect to sn-2 positional distribution.BCFAs were reduced with lactation stage.Then,lipids of vernix and meconium was isolated and seprated by TLC,and the fatty acid were analyzed.The results show that BCFAs accounted for 17.16% of the total fatty acids of the vernix,and the carbon chain length ranged from C12 to C26.The major BCFAs were both anteiso-BCFAs and iso-BCFAs.The content of BCFAs in vernix triglyceride is about 19.8%.The wax ester fraction of vernix contained the highest content of BCFAs(18.78%),and the fatty acid content of BCFAs in the FFA fraction was 15.14%,indicating that the BCFAs were evenly distributed in various lipid types of vernixl lipids.For this reason we estimate that approximately 214.2 mg of BCFAs was swallowed into the digestive tract during the last month of pregnancy.The content of BCFAs in fatty acids in term meconium lipids is approximately 10.24%,and the total BCFAs content in meconium was estimated to be approximately 20.9 mg.The total BCFAs content of meconium lipids in preterm infants was about 5.55%,which was lower than that of term meconium.The amount of BCFAs ingested in vernix lipids was higher than that in the meconium lipids,indicating that most of the BCFAs was absorbed when it entered the digestive tract.Finally,the fatty acid composition in lanolin was analyzed by GC-MS.The main saturated fatty acids were found,and nearly 50% were BCFAs,mainly anteiso-BCFAs and iso-BCFAs,including all detectable BCFAs in vernix lipids.This shows that lanolin is a potential natural source of BCFAs,especially central range of BCFAs chain length like that found in the vernix and breast milk(48.57%).BCFAs has a significant inhibitory effect on the formation of biofilm.The concentration of BCFAs at more than 80 ?g/mL can significantly inhibit the production of purple pigment by C.violaceum.The inhibition rates of BCFAs(1/2 MIC)on Pseudomonas aeruginosa,Staphylococcus aureus,and Salmonella biofilms were 12.96%,28.99%,and 36.9%,respectively.The inhibition was concentration dependent.