Aims: Conjugated hydroxycinnamates, such as chlorogenic acid (caffeoyl-quinic acid), are widely consumed in a Western diet, coffee being one of the richest sources. Ingested hydroxycinnamate esters can reach the large intestine essentially unaltered, and may then be hydrolysed by esterases produced by the indigenous micro¯ora. This study is aimed at identifying bacterial species responsible for the release of natural antioxidants, such as hydroxycinnamic acids, in the human large intestine. Methods and Results: Thirty-®ve isolates recovered after anaerobic batch culture incubation of human faecal bacteria in a chlorogenic acid-based medium were screened for cinnamoyl esterase activity. Six isolates released the hydroxycinnamate, ferulic acid, from its ethyl ester in a plate-screening assay, and these were identi®ed through genotypic characterization (16S rRNA sequencing) as Escherichia coli (three isolates), Bi®dobacterium lactis and Lactobacillus gasseri (two strains). Chlorogenic acid hydrolysing activities were essentially intracellular. These cinnamoyl esterase-producing organisms were devoid of other phenolic-degrading activities. Conclusions:The results show that certain gut bacteria, including some already recognized as potentially health-promoting (i.e. species belonging to the genera Bi®dobacterium and Lactobacillus), are involved in the release of bioactive hydroxycinnamic acids in the human colon. Signi®cance and Impact of the Study: Free hydroxycinnamates, including caffeic, ferulic and p-coumaric acids, exhibit antioxidant and anticarcinogenic properties both in vitro and in animal models. Given that the gut¯ora has a major role in human nutrition and health, some of the bene®cial effects of phenolic acids may be ascribed to the micro¯ora involved in metabolism.

24This work represents an investigation into the presence, abundance and diversity of

Stool consistency and bacterial composition of infants taking SYN1 0.8 g/dL or GOS:FOS-supplemented formula were closer to the breast-fed pattern. There was no risk of dehydration.

13 Diet-microbe interactions play a crucial role in infant development and modulation of the early-life 14 microbiota. The genus Bifidobacterium dominates the breast-fed infant gut, with strains of B. 15 longum subsp. longum (B. longum) and B. longum subsp. infantis (B. infantis) particularly prevalent. 16Although transition from milk to a more diversified diet later in infancy initiates a shift to a more 17 complex microbiome, specific strains of B. longum may persist in individual hosts for prolonged 18 periods of time. Here, we sought to investigate the adaptation of B. longum to the changing infant 19 diet. Genomic characterisation of 75 strains isolated from nine either exclusively breast-or formula-20 fed (pre-weaning) infants in their first 18 months revealed subspecies-and strain-specific intra-21 individual genomic diversity with respect to glycosyl hydrolase families and enzymes, which 22 2 persistence in a single host and may contribute to rational development of new dietary therapies for 31 this important developmental window. 32 33 35 particularly the ones involved in the degradation of breast milk-associated human milk 52 oligosaccharides (HMOs) (8). The presence of these genes is often species-and indeed strain-53 specific, and has been described in B. breve, B. bifidum, B. longum, B. infantis, and more rarely in B. 54 pseudocatenulatum (8,(25)(26)(27). However, previous studies have indicated co-existence of 55Bifidobacterium species and strains in individual hosts, resulting in interaction and metabolic co-56 operation within a single (HMO-associated) ecosystem (1, 28). 57Transition from breastfeeding to a more diversified diet and the introduction of solid foods has been 58 considered to initiate the development of a functionally more complex adult-like microbiome with 59 genes responsible for degradation of plant-derived complex carbohydrates, starches, and 60 xenobiotics, as well as production of vitamins (29, 30). Non-digestible complex carbohydrates such 61 as inulin-type fructans (ITF), arabino-xylans (AX) or arabinoxylo-oligosaccharides (AXOS) in 62 3 complementary foods have been proposed to potentially exert beneficial health effects through 63 their bifidogenic and prebiotic properties and resulting modulation of the intestinal microbiota and 64 metabolic end-products (31)(32)(33)(34). 65Despite the shift in microbiota composition during weaning, specific strains of Bifidobacterium, and 66 B. longum in particular, have previously been shown to persist in individuals over time (35, 36). B. 67 longum is currently recognised as four subspecies: longum and infantis (characteristic of the human 68 gut microbiota), and suis and suillum (from animal hosts) (37, 38). It is considered the most common 69 and prevalent species found in the human gut, with B. longum subsp. infantis detected in infants, 70 and B. longum subsp. longum widely distributed in both infants and adults (39, 40). The differences 71 in prevalence between the two subspecies, and the ability of infant, adult and elderly host t...