[thedoc (OP)]

Thomas Greig  asked the Naked Scientists:















   The amazing micro-biome in our guts is mentioned more and more frequently, often in the same sentence as faecal transplants.  There are also products and foodstuffs containing live bacteria that are claimed to help improve or replenish the bacteria in the gut.  































My question is, how do these bacteria, from, say, live yogurt or a pill form transpoosion, survive the aggressive environment of the stomach?































Thanks,















Thomas















What do you think?

[evan_au]

There are hints that newborns have a very different environment in their guts, which allows them to pick up antibodies from mothers milk, without actually chopping them up into their constituent amino acids, as an adult digestive system would.

Presumably, this milder environment would also allow them to pick up bacteria from people with whom they have close contact (especially the mother, during birth).

Some live bacteria are tolerant of the acid conditions in the stomach, although it would be a rare bacterium that could survive while passing through the acid conditions of the stomach, and then thrive in the more basic conditions further down the gut. However, some bacteria can enter a hardy spore stage, which would allow them to pass through these adverse environments, returning to active growth when they find conditions that better suit their lifestyle.

The unfortunate fact is that probiotics are limited to a small number of bacteria species that can be easily grown in a factory environment. In contrast, a healthy human micro biome contains many bacterial species which we can recognise from their genetic fingerprints, but currently have no way of growing in the lab, or of delivering to an appropriate ecological niche in the gut (short of a "poo transplant").