Lecture 6 Flashcards
what do B. theta and B. caccae prefer to break down?
Bt prefers levan over insulin, B. caccae is the opposite.
what happens when mice are colonised with Bt and B. caccae and fed insulin?
the B. caccae outcompetes Bt and ‘wins’.
what conclusions are made from the Bt and B. caccae studies?
glycan preference seems to predict competitiveness, but its possible that its not glycan preference but another factor driving it.
what happened when the B. caccae insulin PUL was transplanted into Bt?
the transplanted Bt strain can now compete in an insulin environment with B. caccae.
what is the infant gut dominated by pre weaning?
Bifidobacterium spp. especially B. infantis
what does human milk contain large numbers of?
contains large numbers of complex oligosaccharides (HMOs). Bifidos are known to be very good at using HMOs that’s why there’s high Bifidobacteria levels pre weaning. (70%).
what has been added to formula milk for women who don’t breastfeed?
HMOs.
what bacteria can also use HMOs?
Bacteroides but they don’t dominate the gut.
what happens when Bt and B. infantis compete in a mucin environment?
Bt thrives and grows well with not much B. infantis growth.
what happens when Bt and B. infantis are grown in a mix of different oligosaccharides?
both bacteria thrive and grow well.
what is Lacto-N-neotetraose? (LNnT)
a specific HMO found within breastmilk.
what happens when Bt and B. infantis are grown in an LNnT environment?
bifido infantis thrives because it has specificity to LNnT.
why do we want to maintain Bacteroides in the infant gut too?
we want them in the post weaning gut so that the becteroides are already there and don’t have to arrive to the body.
what happens to the microbiota in a low-fibre diet?
mucin-degrading bacteria increase. the diversity of microbiota decreases.
what happened in mouse models when a mouse with a low-fibre diet was switched to a high fibre diet?
the degree of microbiota recovery decreased, implying extinction of some microbial species.
what was the microbiota like in the offspring of a low fibre diet mouse?
in generation 2, there was further receded microbial diversity, in generation 3 (generation 2 offspring), there was even more reduced diversity.
what was the microbiota recovery in generations 2 and 3 mice when switched to a high-fibre diet?
egeneration 2 showed less recovery and generation 3 showed even less recovery and still had a low microbiota diversity.
where does the main evidence of the role of fibre in microbial diversity come from?
the analysis of people from traditional non-industrial societies where levels of fibre intake are much higher then in the western ‘industrialised’ world.
what is the microbiome like in people from non-industrialised societies?
they have a higher microbiota diversity, and almost no chronic diseases like IBD and colo-rectal cancer.
what happens to indigenous people who move to a western country or adapt a wester lifestyle?
they have higher incidences of IBD and CRC due to reduced microbiota diversity.
