necessary microorganisms

J

John Connellan

Valued Senior Member
Somebody in the General philosophy forum (would u believe) gave me the idea for this thread.

We all know that there are many types of "good" bacteria present in the human body which play an important role in our biology. What I was wondering is , are these microorganisms absolutely necessary in keeping us alive. If we somehow rid the body of these microorganisms (with an antiseptic) could we survive for long? Sure the body has adapted to this mutualistic symbiosis as is it the easy way out, but have we become so dependent on these organisms that we cannot exist independently?
 
This depends on the organism. Some (depending on their normal diet) are dependent on certain microorganisms, either for processing of otherwise unusable food sources, or to synthesize essential nutrients (e.g. certain amino acids or co-factors), as most "higher" organism lack the ability to synthesize all their nutrient requirements.
The second dependence is the use of non-pathogenic bacteria as a protection of pathogenic ones. The normal flora that colonizes use up all the niches that otherwise might get occupied by pathogens.
Thus, with the correct diet and a sterile environment it is possible to keep animals (like e.g. humans) viable without an endogenous bacterial colonization.
This is, in fact done for instance for sterile mice, that are used for certain studies.
 
Intestinal microbes do have influence on the host. I'm too lazy to look it up, but luckily there was a related story recently in the news.

http://sciencenow.sciencemag.org/cgi/content/full/2006/1220/2
Do Gut Bugs Make You Fat?
If the scale has tipped too far in the wrong direction, perhaps you should blame the bugs living in your gut. Some microbes are better at wringing calories out of those holiday meals than others, researchers report in two papers in today's Nature. Transferring such high-octane bugs into lean mice causes the rodents to plump up, suggesting a microbial contribution to obesity.



Ley put a dozen obese volunteers on either a low-fat or a low-carbohydrate diet for a year. At regular intervals, she surveyed their intestinal microbial communities....After a year, the volunteers had lost 2% to 6% of their weight, the Firmicutes had dropped to 73%, and the Bacteroidetes increased to about 15%, irrespective of the diet followed

and

Peter Turnbaugh analyzed the genomes of gut microbes in two pairs of mice. In each pair, one mouse was healthy, while the other, a sibling, carried two mutant copies of a gene called leptin,which made it obese. Microbes from the obese mice had more genes for processing starches and complex sugars and produced more simple sugars and fatty acids--that is, calories--for the gut to absorb. When the researchers transplanted microbes from the obese mice into germ-free mice, the recipients had a 47% increase in body fat over 2 weeks. In contrast, germ-free mice supplied with microbes from lean mice had only a 27% increase, says Gordon.

apparently having a certain distribution of microorganisms can make you more or less fat.
 
hrm, that's interesting...

im not sure,
i do know that bacteria are quite effective for the immune system.
there's bacteria that also helps synthesize vitamin k, for us which is important for blood; however, not enough for human survival... we'll still need an intake.
other such bacteria aid in digestion, absorption, etc.

there's bacteria that prevents yeast overgrowth.
that's pretty important, i think.

even e.coli helps with digestion..

but i don't know how important they all are.
there's so much bacteria that helps, though.
so i'm pretty sure your survival is limited if one were to have his/her system cleaned of bacteria.

especially as you get older.
 
I know it is below us to look at textbook stuff but maybe it can generate a bit of discussion to list the general list of the benefits of bacterial flora in the human intestinal tract.
http://www.textbookofbacteriology.net/normalflora.html
1. The normal flora synthesize and excrete vitamins in excess of their own needs, which can be absorbed as nutrients by the host. For example, enteric bacteria secrete Vitamin K and Vitamin B12, and lactic acid bacteria produce certain B-vitamins. Germ-free animals may be deficient in Vitamin K to the extent that it is necessary to supplement their diets.

2. The normal flora prevent colonization by pathogens by competing for attachment sites or for essential nutrients. This is thought to be their most important beneficial effect, which has been demonstrated in the oral cavity, the intestine, the skin, and the vaginal epithelium. In some experiments, germ-free animals can be infected by 10 Salmonella bacteria, while the infectious dose for conventional animals is near 106 cells.

3. The normal flora may antagonize other bacteria through the production of substances which inhibit or kill nonindigenous species. The intestinal bacteria produce a variety of substances ranging from relatively nonspecific fatty acids and peroxides to highly specific bacteriocins, which inhibit or kill other bacteria.

4. The normal flora stimulate the development of certain tissues, i.e., the caecum and certain lymphatic tissues (Peyer's patches) in the GI tract. The caecum of germ-free animals is enlarged, thin-walled, and fluid-filled, compared to that organ in conventional animals. Also, based on the ability to undergo immunological stimulation, the intestinal lymphatic tissues of germ-free animals are poorly-developed compared to conventional animals.

5. The normal flora stimulate the production of cross-reactive antibodies. Since the normal flora behave as antigens in an animal, they induce an immunological response, in particular, an antibody-mediated immune (AMI) response. Low levels of antibodies produced against components of the normal flora are known to cross react with certain related pathogens, and thereby prevent infection or invasion. Antibodies produced against antigenic components of the normal flora are sometimes referred to as "natural" antibodies, and such antibodies are lacking in germ-free animals.
Click to expand...

No.1 cpt.scruffy already mentioned. The bacteria do produce vitamins we can use and break down stuff we cannot break down.
 
To put it into perspective, microorganism are as such not essential, as sterile animals are viable. However, under normal conditions (that is, non-sterile) their survival chance is severely handicapped. And in addition (as spurious pointed out) there might be potential developmental disadvantages.
 
I do not know the definitive numbers as I was not directly involved in the study with the sterile mice at my old institute. However, I was told that under the given sterile conditions (including silly sterile suits that were far too large for me...) and a strict diet they live as long or even outlive normal mice.
But I also recall that they had to kill off a complete line due to a sudden fast-spreading infection.
 
There are enzymes that break down food, bacteria generally disposes unwanted products. My guess is you will be in serious trouble without bacteria.
 
Mice raised in germ-free enviroment have been shown to have longer mean life span ...

http://scienceweek.com/2003/sw030131.htm

but I found several links , saying that germ-free animals were highly susceptible to disease , when removed from germ-free environment , due to
an underdeveloped immune system ...
 
Cyanobacteria created our oxygen environment that we need to breathe. Without decomposers we could not survive in a sewage environment. Composting is essential.

Microbes constitute the vast majority of marine biomass and are the primary engines of Earth’s biosphere. They are the primary catalysts of energy transformation, and fundamental to the biogeochemical cycles that shape our planetary atmosphere and environment. From an evolutionary perspective, they are of pivotal importance. They were the only kinds of life on Earth for approximately 80% of the planet’s history. All multi-cellular life depends upon microbial processes. The microbes can live without us but we are totally dependent upon them for our continued survival.
Click to expand...
http://www.coml.org/medres/microbe2006/CoML_ICOMM Public_Release_07-31-06.pdf

What is the function of the intestines and colon without microbes? Over 1000 species are used to convert food to energy. Flora are essential in protection against enteric bacterial pathogens.

The human genome is but a fraction of what it takes to make a human. The collective bacterial genome in the average person is so large that it contains between 60 and 100 times as many genes as the human genome. Up to 100 trillion microbes, representing more than 1,000 species, make up a motley "microbiome" that allows humans to digest much of what we eat. We lack the means to break down the food we eat into energy essential for our survival and, while bacteria could survive perfectly well without us, we would be doomed without the toil of bacteria that graze in our guts. We're entirely dependent on this microbial population for our well-being. A shift within this population, often leading to the absence or presence of beneficial microbes, can trigger defects in metabolism and development of diseases such as inflammatory bowel disease.
Click to expand...
http://www.buffalo.edu/news/pdf/June06/LondonTelegraphGillGut.pdf
 
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