which was almost 100 million years in dormant stage..

https://www.nature.com/articles/s41467-020-17330-1

The bacteria have ability to still dormant in adverse condition for years , also some have abilty for spore production

That depends on the spp. of bacteria if they form biofilm or spores so they can survive without food for a long period. Especially when form spores, bacillus form spores so, they can survive for a long period as they preserved their genetic material in the core of spores and the spores were highly resistant to unfavorable conditions. Spore formation is one of the bacterial clever strategies adapted to accommodate the harsh environment.

Hussein A.M Al. Bayati . Al. Baiati and Manal Hadi Kanaan Thank you for your quick response..

Regards Wani

When favored nutrients are exhausted, some bacteria may become motile to seek out nutrients, or they may produce enzymes to exploit alternative resources. One example of an extreme survival strategy employed by certain bacteria is the formation of endospores. This complex developmental process is often initiated in response to nutrient deprivation. It allows the bacterium to produce a dormant and highly resistant cell to preserve the cell's genetic material in times of extreme stress. Endospores can survive unfavorable environments that would normally kill the bacterium. The resistance of spore due to Impermeability of the spore cortex and coat (its unique cellular structure), low water content, low metabolic activity, high content of calcium, and dipicolinic acid. So, as Genuss bacillus form spores for that, I agree with Dr. Hussein A.M Al. Bayati . Al. Baiati they can be dormant and survive for years.

There is no death relating to the age of bacteria. Of course, there are events of lysis, necrosis and PCD in few cases, but not due to aging.

Manal Hadi Kanaan and Shujaat Ali Thank you for the response

The question that K. M. N. Saquib Wani asks is actually quite complicated. If you want to consider spores then of course the answer is very long, years certainly. For non-spore forming organisms it is quite variable and will vary significantly with the organism. The stories of 100 million year old bacteria from bottom of the sea, or viable spores embedded in amber tell what the upper limit is but that certainly is not the answer most of the time.

It is important to specify are you asking for survival of MOST of the bacteria, or the survival of SOME of the bacteria, the answer will be quite different. For example if you grow an overnight culture of E. coli and resuspend in saline then you get a fairly rapid die-off of cells within a week or two. More than 99.9% of the cells will not grow. But a fraction of the cells will remain viable for much longer time (months). We often forget that a a tiny fraction of a very large number (bacteria per ml) is still a large number.

Michael J. Benedik ( We often forget that a a tiny fraction of a very large number (bacteria per ml) is still a large number )

Traci L Testerman ( Survival of strict anaerobes will depend on maintaining an anaerobic environment during storage. Absence of UV light is also important. )

Thank you for the pointing out the exact details and detailed response.

Regards

Wani

Bacillus withstand starvation by forming dormant spores. When the nutrients are available again in their environment, these spores sporulate again which determines the survival of these bacteria in the environment. Many Gram-positive bacteria have this ability to differentiate into endospores and to revert from the dormant state through spore germination and subsequent outgrowth, thereby resuming the vegetative growth state. However, the exact time or the maximum average time bacteria can be active or turn completely dormant depend on many factors. First it can depend on the particular type of microorganism. On the other hand, environmental conditions, might affect the time taken to sporulate. It also could determine the resistance of these spores. Moreover, the capacity for revival will be affected by environmental influences on their molecular composition. Some studies have found that the cells have a long-term memory that controls their responses to nutrient-induced spore revival. Presences of some chemicals in spore core have also reported to be influencing these factors. For instance, presence of alanine dehydrogenase supports the spore germination in an effective way. Therefore, I suppose the exact time taken for these processes should be studied with a common laboratory spore forming Bacillus and understood. These times may be widely varied even for the same organism.

Sandhya Jayasekara Thanks for the details....

Regards Najam

this depend on the type of bacteria where the bacteria that form spore can stay for million years.

Thank you Dr. Hassan

1. Nutrient concentration can NEVER go in the extracellular liquid to zero. When we transfer cells from growing medium into nutrients-free buffer, there are still some nutrients left and [more important] some cells lyse releasing available substrates. Besides, a flask with starving bacteria receives the volatile organic compounds from lab air, such as acetaldehyde, ethanol, low molecular weight fatty acids, ethers etc. This flux is low but it does help to survived cells to grow although VERY slowly. Obvious exception is amber and other enclosed bodies, where life processes are stopped because of complete isolation.

2. Actively growing culture is more-or-less homogeneous but starving population is AWAYS heterogeneous being composed of several subpopulations, e.g. still active cells, dormant cells (could be various degree of dormancy) and damaged/dead cells.

3. Bacterial endospore is not the only form of dormancy. There are exospores, cysts, arthrospores etc. Besides we know now that almost any taxonomic group produces morphologically indistinguishable from the normal morphotype the VBNC (Viable-but-not-Cultivable) cells. Some of them can be resuscitated under non-starving conditions, some not.

4. I fully agree with Traci L Testerman above: Reaction to starvation is a dynamic process, and cells under starvation change their quality (composition of membranes, expression profile, maintenance ratio etc.) that increases their life under stress. Also certain mutations take place discovered two decades ago by Roberto Kolter at Harvard for E coli. It is called GASP (Growth Advantage in Stationary Phase) mutation.

5. Finally addressing to Najam Wani, to summarize the points above, your question does not have answer expressed by single number, how long cells remain viable under starvation. Even for particular organism, say, E coli or Bacillus subtilis it varies for individual members of heterogeneous population. Generally starvation phenomenon is multidimensional but we are pretty close now to its understanding and are able to generate mathematical models to predict starvation response dynamics.

Nicolai S Panikov Thank you so much for your detailed response. It has indeed helped me in understanding the process clearly. You havr tried to include minute details which were very necessary for a better understanding.

Regards

Wani