Bacteria Colony

[Pat Mary]

We have had questions of late about keeping the bacteria colony alive while there is no ammonia source.  Approximately how long do we have before the point of no return is reached?  Can a tank be dormant for a few days, a week or two or a month?  I know that the period depends on several things such as how large the colony is but, in general, it would be great to know about how long of a period one has while using a test kit to monitor the situation.  I always thought a few days was the limit but have learned lately that it can be longer.

[russ]

That is as close to a relative question that I can think of, but  a good one to say the least  There are a few variables involved in determining how long a thriving bacteria colony will last (or at least survive). Let me first start out by saying that bacteria responsible for ammonia conversion to nitrite will last longer than the critters that convert nitrite to nitrate. Dormant status will need to be defined though because there is a difference. Dormant means basically at rest with no progression or regression (lets just call it sleeping) Of course this is very simplified. In respect to your question, I'm assuming that you are referring to a previously well established tank that contained fishes, but all the fish have been removed and not replaced as yet.

Now, some of those considerations (variables) that will determine how long a bacteria colony remains viable (in this respect, meaning, not dormant).

* What exactly is inside the aquarium?
* Is there any remaining proteins in the water column?

Nitrification can take place as long as there are any organics remaining in the aquarium and not otherwise compromised, through mineralization. The break down of these organics will produce ammonia and the cycle can continue. Not as vibrant as an well established thriving tank, but still going none the less. How long? The more organics left and proteins that can be broken down, the longer.
 

[Pat Mary]

So, I understand you to mean that it is unknown how long the bacteria will last but testing will give a good indication.  I can understand that.  But. I guess what I would really like to know is why, at least during the time I have been on this site, did we sort of present it as Gospel that the bacteria would die without an ammonia source?  I feel sort of foolish that I and others gave this information out without anything to back us up.  I do realize that we evolve in the hobby but we gave out false information as the only way to go without batting an eye.  I feel bad about that. 

[TwoTankAmin]

There is a wealth of scientific research on this topic. I can offer the following links in response to your question re ammonia oxidizing bacteria (AOB):

Growth at Low Ammonium Concentrations and Starvation Response as Potential Factors Involved in Niche Differentiation among Ammonia-Oxidizing Bacteria
Annette Bollmann*, Marie-José Bär-Gilissen and Hendrikus J. Laanbroek
Appl. Environ. Microbiol. October 2002 vol. 68 no. 10 4751-4757
http://aem.asm.org/content/68/10/4751.full

Strategies of aerobic ammonia-oxidizing bacteria for coping with nutrient and oxygen fluctuations
Joke Geets, Nico Boon and Willy Verstraete
FEMS Microbiology Ecology Volume 58, Issue 1, pages 1–13, October 2006
http://onlinelibrary.wiley.com/doi/10.1111/j.1574-6941.2006.00170.x/full

Influence of Starvation on Potential Ammonia-Oxidizing Activity and amoA mRNA Levels of Nitrosospira briensis
Annette Bollmann, Ingo Schmidt, Aaron M. Saunders, and Mette H. Nicolaisen
Appl. Environ. Microbiol. March 2005 vol. 71 no. 3 1276-1282
http://aem.asm.org/content/71/3/1276.full

Here is a much less technical piece of information from Dr. Timothy Havanec who was one of the major researchers who identified the specific bacteria at work in aquariums. He is writing about how bacteria in a bottle (a starter culture) are able to survive:

Nitrifying bacteria can live in a bottle for a while. Many think that nitrifying bacteria cannot live in a bottle and will say the reason is because nitrifying bacteria don’t form spores like other bacteria. This is a half-truth. Nitrifying bacteria don’t form spores, but that doesn’t mean they can’t last in a bottle (think about it – if nitrifying bacteria could not survive poor conditions, how would they have survived for millions of years?) They can live in a bottle but under optimal conditions, and the time period is about one year. The nitrifying bacteria don’t die in the bottle; their activity level drops and eventually it becomes so low that there is little measurable positive effect when they are poured into the aquarium water. Provided the nitrifying bacteria in the bottle were not subject to bad environmental conditions (see the next paragraph), they can last about one year in a bottle.

No special preservation chemical or substance has been demonstrated to extend this time period. Refrigerating the bacteria is the only thing that has been shown to measurably extend their shelf life........

Nitrifying bacteria are sensitive to environmental conditions – even when the bacteria in the bottle are the correct species, there are certain environmental conditions that harm and even kill the bacteria while they are in the bottle, leading to their inability to accelerate the establishment of nitrification. The first condition is being exposed to temperatures outside the range they can survive. If the liquid in the bottle freezes, the nitrifying bacteria are killed. It doesn’t matter the brand – freezing kills the nitrifying bacteria. High temperatures also can kill or damage nitrifying bacteria. If the bottle is exposed to 110°F for a day or so, the bacteria can be killed. Prolonged exposure to temperatures over 95°F drastically reduces the shelf life of nitrifying bacteria.

from http://www.drtimsaquatics.com/nitrifying-bacteria-mixtures-work-provided

It is important to understand the difference between how bacteria react in terms of lower ammonia vs no ammonia. In the first instance, the size of the bacterial colony will adjust. This also applies to the reverse where ammonia levels increase. It is no different that how any animal, including man, react when there is too little food for a given population, some starve to death and reproduction slows or stops. Plenty of food and its the reverse.

In terms of the life cycle of nitrifying bacteria, This should help:

Determination of the Decay Rate of Nitrifying Bacteria
S. Salem,1 M.S. Moussa,2 M.C.M. van Loosdrecht1
1Department of biochemical engineering, Delft, University of Technology, Julianalaan 67, 2628 BC, Delft, The Netherlands
Published online 5 April 2006 in Wiley InterScience (www.interscience.wiley.com).
from https://www.researchgate.net/profile/Mark_Van_Loosdrecht/publication/7180555_Determination_of_the_Decay_Rate_of_Nitrifying_Bacteria/links/55cef4f408ae118c85bed455.pdf

One quick quote from the above paper: "The decay rate of ammonia oxidizers and nitrite oxidizers was the same at the corresponding conditions."

A side effect of all of the above relates to the motility of the bacteria. At any given time the number of bacteria that are motile vs attached in the biofilm changes. The change is triggered in response to the availability of nitrogen in the system. The more N there is, the fewer of them that are motile. But when things change and food is less plentiful, more of the become motile. This allows some number to try and move to where conditions are better.

In the past decade it has been discovered that not only do the autotrophs oxidize ammonia, but so too do some Archaea (AOA).

Archaea (domain Archaea) Any of a group of single-celled prokaryotic organisms (that is, organisms whose cells lack a defined nucleus) that have distinct molecular characteristics separating them from bacteria (the other, more prominent group of prokaryotes) as well as from eukaryotes (organisms, including plants and animals, whose cells contain a defined nucleus).

from http://www.britannica.com/science/archaea

The AOA have been found in aquariums, especially sw tanks. In several interchanges i have had with several microbiologists the conclusion appears to be that both mircroorganisms are likely present in most tanks. In some the AOA seem to be dominant in others it is the AOB. In many cases it is both. The primary difference between the AOA and the AOB is that the AOA can thrive on the lowest levels of available ammonia and tend to do worse the higher ammonia levels go. The bacteria also appear to do better in more highly oxygenated water. What is clear is that AOA and AOB seem to coexist in many environments. Also, the nitrite oxidizing bacteria (NOB) have been well researched but, to date, no nirite oxidizing archaea have been found.