Article 4 (Source: Moossavi et al., 2019, Cell Host & Microbc 25, 324-335)       Although previously considered sterile, breastmilk is now known to contain acomplex community of bacteria that helps establish the infant gut microbiota. If thisprocess is disrupted, the infant may develop a dysbiotic microbiota, causingpredisposition to chronic diseases such as allergy, asthma, and obesity. Recent studieson humar n milk microbiota suggest that it might be affected by local pathologies of thebreast, mode of delivery, antibiotics, maternal heaith, and gestational age. However,these findings have not been reproduced in large-scale studics, and the determinants ofmilk microbiota are still mostly unknown.       Two main pathways have been proposed to explain the origin of milk microbiota:entero-mammary translocation of the maternal gut microbiota and retrogradeinoculation by the infant's oral microbiota. The fact that colostrum collected evenbefore the first infant feeding already contains a microbial community supports theentero-mammary pathway, while the similarity of infant oral microbiota to breastmilkmicrobiota supports the retrograde pathway. It is plausible that both pathways arecontributing to the bacterial content of human milk. Depending on the source of bacteria,different factors could contribute to shaping the milk microbiota. Factors influencingthe mother's gut microbiota such as obesity or diet could affect the bacteria originatingfrom the maternal gut, while factors influencing the infant's microbiota such as modeof delivery, older siblings, complementary feeding, and mode of breastfeeding (directlyat the breast versus pumped and bottled breastmilk) could potentially alter the bacteriaderived from the infant's oral cavity. Other milk compor nents such as human milkoligosaccharides (HMOs), milk fatty acids, h ne cells, and antibodiescould also modulate the milk "microenviront ment" and create a niche constraintaffecting composition of the microbial community. Additionally, factors that couldimpact the overall milk composition such as circadian rhythm and lactation stage couldindirectly affect the milk microbial community.         Studies addressing these potential determinants of milk microbiota have beenlimited by small sample size, low sequencing depth, and lack of control for confoundingfactors. The objcctive of this study was to profile the milk microbiota in a large sampleof healthy mother-infant dyads and examine the association of maternal, infant, early-life, and milk factors with milk microbiota composition.
【題組】26. What is the meaning of "dysbiotic microbiota" in this article?
(A) Microbialimbalancc
(B) Beneficial bacteria in the gut
(C) Pathogenic microbes in the milk
(D)Microbes that can generate oligosaccharides.