Dissertation defence (Paediatrics): MSc Anastasia Mantziari

MSc Anastasia Mantziari defends the dissertation in Paediatrics titled “Human milk: microbiota composition and impact of processing on probiotic properties” at the University of Turku on 10 May 2024 at 12.00 (University of Turku, Medisiina C, Osmo Järvi lecture hall, Kiinamyllynkatu 10, Turku).

The audience can participate in the defence by remote access: https://utu.zoom.us/j/68831864991 (passcode 175750)

Opponent: Professor Hani El-Nezamy (University of Eastern Finland)
Custos: Professor Seppo Salminen (University of Turku)

Doctoral Dissertation at UTUPub: https://urn.fi/URN:ISBN:978-951-29-9675-9


Summary of the Doctoral Dissertation:

The preterm infant is often characterized by an underdeveloped immune system and disruption in the healthy balance of microbial species in the gut, impacting infant health. Interventions in Neonatal Intensive Care Units, such as donor human milk, fortifiers (protein supplements), and probiotics, aim to modify the gut microbiota composition of preterm infants addressing this imbalance. This thesis explored human milk microbiota composition and factors affecting probiotic properties.

The thesis revealed that term milk is more diverse in terms of its microbiota composition than preterm milk. Moreover, upon reaching the term equivalent age, the human milk microbiota composition of mothers who delivered prematurely closely resembled that of term milk, suggesting that breastfeeding likely contributes to the maturation of microbial communities. The research further assessed the stability of probiotics specifically Lacticaseibacillus rhamnosus GG and Bifidobacterium animalis ssp. lactis Bb12, showing that both probiotics maintained their viability for up to 72 hours. Additionally, we found that fortification of donor human milk with liquid or powdered human milk fortifiers did not adversely affect the adhesion properties of these probiotics. We finally explored the role of polyamines, in modulating the adhesion of probiotics and pathogens with intestinal mucus in infants. The presence of the polyamine spermidine significantly enhanced the adhesion of Bb12 in infant mucus under six months, as the polyamine spermine reduced the adhesion of Cronobacter sakazakii.

In conclusion, the thesis showed that the microbiota composition of preterm human milk gradually aligns with that of term milk as infants grow. Furthermore, probiotic adhesion remains unaffected by cold storage or donor milk fortification. However, the impact of polyamines on bacterial adhesion to mucus depends on bacterial strain and donor age. Overall, these insights should be considered for developing optimized gut colonization strategies for infants, particularly for those born preterm.
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