Are you asking whether being unculturable is beneficial to an organism's long-term survival? Every organism requires certain environmental conditions and resources to live, whether they are freely available in the environment or must be shared with a host. If those requirements aren't met then the species must be able to adapt (i.e., sporulation under starvation conditions). Therefore, it would seem that being unculturable is more of a side effect of a specific path of evolution than a factor directly impacting evolution.

Of course, there's also the issue that some of the most commonly cultured lab organisms (E. coli, B. subtilis, and such) are cultured exactly because they're easy to grow in the lab. Strains of these species are not genetically diverse and are ideally adapted for pure culture. We hardly ever see a pure microbial culture in the wild so these favorite lab organisms aren't really representative of real-world conditions. 

kindly clear the question what about host...... is their is any transformation....or u have used term host for substrate.....

Are you asking whether being unculturable is beneficial to an organism's long-term survival? Every organism requires certain environmental conditions and resources to live, whether they are freely available in the environment or must be shared with a host. If those requirements aren't met then the species must be able to adapt (i.e., sporulation under starvation conditions). Therefore, it would seem that being unculturable is more of a side effect of a specific path of evolution than a factor directly impacting evolution.

Of course, there's also the issue that some of the most commonly cultured lab organisms (E. coli, B. subtilis, and such) are cultured exactly because they're easy to grow in the lab. Strains of these species are not genetically diverse and are ideally adapted for pure culture. We hardly ever see a pure microbial culture in the wild so these favorite lab organisms aren't really representative of real-world conditions. 

Dear Pandey, 

It is a question of curiosity. Mycobacterium leprae does not grow on cultures and it needs a specific host but Mycobacterium tuberculosis, a closly related one doesnt so. In the process of evolution, M. leprae has lost its viability to grow on non specific hosts. So is that a boon to them? 

Each organism have his own special conditions to grow, many environmental aspects could affect it, perhaps many organisms don't can be cultivated in lab conditions it is not convenient for us, but I think is not a problem for them.

Take into account, is not that they are "unculturable", is just that we don't know their specific requirements or environmental conditions. Also another hypothesis is the overall advantage of fast growers over slow ones. Take for example sponge-associated bacteria, an exciting metagenomic field of research for its potential biotechnological implications. They might need some sort of symbiosis with the sponge to reproduce, and given that, we are also unable to reproduce sponge cells in the lab, then the bacteria is also unable to grow. There is also some interesting research on how to create new growth media for difficult organisms, for example New Detection Systems of Bacteria Using Highly Selective Media Designed by SMART: Selective Medium-Design Algorithm Restricted by Two Constraints.

It's not clear what is "boon"  and "bane" in this case. Till the microorganism can not be cultivated in the lab and still exists in nature, we can estimate it. There is the "abuse" between the lab conditions and nature, so I would say that the more relevant question is: "is it boon or bane for scientists". The answer for this question is clear.

Thanks J. Harry Caufield, Professor Jazmín Aguilar Medina, Luis Peña,  Sylvain Monteux and Konstantin Ivanov, for your opinions. :)

As others have stated, culturability is a matter of context. The current context is the media we provide them. These medias may not contain the nutrients or other factors required to stimulate their growth. Microbes, depending on their evolution are adapted to particular niches, until we better understand these niches we cannot design conditions favourable for their culture. These organisms exist in nature, so the boon or bane question can only really be answered in the context of their relative fitness under ideal conditions.

Many other organisms were previously unculturable. These include obligate intracellular pathogenic microbes like the Ricketsiae. They're well adapted to their niche, their ability to grow in an artificial environment had no bearing on this.

Dear Ms. Pieper,

That  is a really very nice explanation.

Most birds cannot be easily domesticated for farm use. Chickens are an exception. Was that a boon for them? Most chickens would say no, and yet there are more chickens in the world than people.

To the bacteria it is neither bane nor boon they will continue to inhabit the niche to which they have adapted.  If in understanding how to culture them we take action to provide more or better places for those organisms to survive, then it becomes a boon.  However, most organisms are either cultured because they are tool that provides us a look into how things work or they have direct impact on humankind.

This is relevant typically if the organism is of major importance as a disease agent in humans, animals, or plants.  Culturing them would be of benefit because we could ascertain their mechanism of infection and the conditions under which they become a pathological threat.  Then understanding them becomes a bane.

While understanding our environment and the roles organisms play in it has some importance in general for scientific study.  Mitigation of disease or protection of food supply has been the typical thrust of research.  So most organisms used in study either have financial impact because of illness or disease they cause or the benefit they can provide.  However even many of the easy to culture organism have roles they play in the environment that is unrelated to the purpose for which they are cultured and is perhaps a testimony to their adaptability.