Our bacteria

binbots

I was just wondering where all the bacteria in our bodies comes from? Does it enter the body through the mother during pregnancy? Also how does the body know how much to let in?

HallsofIvy

Much of it comes in through food or water- some in the air we breathe. The body does NOT "know how much to let in". But it can kill some of the bacteria. And the "beneficial" bacteria in the intestine is pretty much controlled based on how much food it gets.

Andy Resnick

You eat them (or drink them, as HallsofIvy mentioned). Several species of infant animals have their mother's feces for a first meal in order to get the bacteria into their gut.

JorgeLobo

Flora are established relatively early in life, much of it from maternal contact, and it will change during life. You'll have more bacterial/microbial cells in and on your body than human cells and their dynamic has to do with available space, substrate, competition with you and other microbe, etc.

Look up the term "microbiome."

binbots

Thanks everyone. So when we are born we are bacteria free. But without these bacteria we will die. That is just interesting to think about.

JorgeLobo

We probably won't die without them but we and they have evolved together so it won't be easy wthout them - one can sustain gnotobiotic (microbe-free) animals.

bobze

Actually we'd probably die without our bacteria. They preform a host of services for us, from helping in digestion to out-competing real "bad" bacteria. Our immune systems evolved with them as well and there is evidence that bacteria and parasites help "pacify" our immune system--Or better keep it occupied such that it doesn't start attacking self-antigens.

Andy Resnick

In practice, we would probably die. However, germ-free animals are an important component of biomedical research, and so it is clearly possible to live without bacteria present.

Q_Goest

Hi Andy, do these germ-free animals have no bacteria in the gut either?

bobze

I agree Andy. The requirements that germ-free animals must be kept under (or even gnobiotic animals where the few strains that do live on them are known) aren't realistic to keeping a human being under. A bacteria free human, outside of a science-fiction novel, is a dead human.

bobze

There are animals that can be completely germ free which can used to study the effects of how a single type of bacteria introduced interact with their physiological and biological functions. Gnobiotic animals are animals with a known limited number of strains of microorganisms living on/with them.

Andy Resnick

Based on the little knowledge I have (I don't do whole-animal research), I think the answer is 'no'. Those animals are kept on a highly regulated diet:

http://www.labdiet.com/products.html

and housed in sterile environments:

http://books.google.com/books?id=Gi6...edding&f=false

(the section on 'deriving' gnobiotic mice is worth reading also)

JorgeLobo

No bobze - gnotobiotic concept also includes germ-free animals.

bobze

Jorge, I didn't say anything that disagreed with that....gnotobiosis (to "know life") refers to knowing an organisms microbial flora--Be that a few strains of known microorganisms colonizing the organism, or "knowing" it posses no microbial flora. Obviously then Jorge, the set "germ-free" belongs to the set gnotobiotic.....But thanks for playin anyway!

mishrashubham

The thread is not about the genus microbiota but about gut flora, microbes present in our intestines.