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So, What Else is New?

by Elio

At the year's end, the me­dia have been pay­ing spe­cial at­ten­tion to mi­crobes. News­pa­pers, ra­dio, and TV have found mi­cro­bial sto­ries wor­thy of their at­ten­tion. Here is a sam­ple:

Obe­sity and the gut flora

Charles Mellin (1597–1649), por­trait Ales­sandro del Borro(?). Fron­tispiece: this paint­ing in the Gemälde­ga­lerie Berlin. Photo Credit Christoph Weigel.

Prac­ti­cally every­one who lis­tens to or reads any sort of me­dia must know by now that some­day we may be able to lose weight by mod­i­fy­ing our gut flora. A cou­ple of pa­pers from the lab of Jef­frey Gor­don (A and B) point to what goes on in the bow­els of both peo­ple and mice. Two bac­te­r­ial groups dom­i­nate in the colon, the Gram-neg­a­tive Bac­teroidetes (mainly Bac­teroides), and the Gram-pos­i­tive Fir­mi­cutes (mainly Clostrid­ium). Their ra­tio, how­ever, varies with the host's heft. The F/B ra­tio is higher in the obese, both mice and hu­man. It looks like the F's are bet­ter at break­ing down food­stuff and pro­viding more en­ergy to the host. Stud­ies of this sort open a lot of ques­tions but they keep Google busy. En­ter gut flora and you get thou­sands of rel­e­vant sites. We must thank Gor­don and col­leagues for shift­ing the public's at­ten­tion from killer spinach to the intrica­cies of the in­ter­ac­tions be­tween mi­crobes and hu­mans in health, not only in dis­ease. 

 

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Stanley Maloy
19 years ago

But the cause vs ef­fect ques­tion re­mains — is the change in com­po­si­tion of gut mi­crobes DUE TO dif­fer­ences in diet and me­tab­o­lism that cor­re­spond to ex­cess weight or does the change in com­po­si­tion of gut mi­crobes PROMOTE the process lead­ing to ex­cess weight?

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moselio schaechter
19 years ago

Stan­ley is right in­so­far as the stud­ies on hu­mans go. How­ever, in their mouse pa­per, the au­thors col­o­nized germ-free mice with in­testi­nal mi­crobes from ei­ther fat or the lean mice. Their claim is that the "fat bugs" made the mice obese, the "skiny bugs" did not. Surely this is nto the last word on thsi mat­ter

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Robert S. Fulghum
19 years ago

Do bac­te­ria in the lower gut re­ally make fat peo­ple fat or do fat people's me­tab­o­lism con­trol the rel­a­tive num­ber of dif­fer­ent species in the GI tract ?
W.E.C. Moore showed in the ru­men of cat­tle (not lower GI flora) that the an­i­mal con­trols the fer­men­ta­tion rate — at least of cel­lu­lose. He had twin steers from each he re­moved the en­tire con­tents of the ru­mens, washed out the ru­mens, and re­placed the con­tents of each steer's ru­men in it's twins ru­men.
Hav­ing pre­vi­ously mea­sured the rate of the di­ges­tion of cel­lu­lose in each an­i­mal and find­ing a dif­fer­ence, he re­peated the di­ges­tion ex­per­i­ment in the an­i­mals af­ter the ru­men con­tents had been re­placed. He found the di­ges­tion rate was char­ac­ter­is­tic of the in­di­vid­ual an­i­mal rather than char­ac­ter­is­tic of the ru­men con­tents (biota) re­placed in the other an­i­mal. In other words, the an­i­mal, not the biota con­trolled the fer­men­ta­tion rate of cel­lu­lose.
I don't re­mem­ber if he ever pub­lished this and I have long since given away my reprint files.
And maybe — just maybe — these were unique an­i­mals. One of them learned to lick the light switch and he would turn the lights on in the barn at night !
My best re­gards to you, Elio.
Bob

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