MadSci Network: Microbiology
Query:

Re: hot mineral springs water

Date: Wed Nov 28 21:18:12 2007
Posted By: Neil Saunders, Computational biologist
Area of science: Microbiology
ID: 1196003422.Mi
Message:

Hi Joann (or Joanne?),

Thanks for your question. The short answer: microorganisms can live almost anywhere, so they will certainly be found in the mineral spring that you describe. Now for a more detailed answer.

First, let's convert the units that you gave to something more informative. 650 ppm sodium is 0.65 g l-1. The atomic mass of sodium is about 23, so that comes to 0.65/23 x 1000 = about 28 mM. Similarly for 1356 ppm chloride (atomic mass 35.5), we get 1.356/35.5 x 1000 = about 38 mM.
Neither of those is especially extreme. The archaeon Halobacterium halobium can grow happily at very high salinity: 4-5 M sodium chloride [1]. In the lab, bacteria are often grown in media which contain 5-10 g l-1 sodium chloride. So the salinity in your spring will support the growth of many microorganisms.

You quote a temperature of 104-106 °F. I assume that this is not a mistake and you do mean Fahrenheit. I know that in the USA Fahrenheit is commonly used, but in science we use either Celsius or Kelvin temperature units. To convert Fahrenheit to Celsius we subtract 32 and multiple by 5/9, to give about 40-42 °C.
Again, this is not especially high. Many (but by no means all) microorganisms grow best between about 30-40 °C. However, even if the temperature of the spring were 104-106 °C, there are microorganisms which would be very happy in there. They are called hyperthermophiles and many can grow well above 100 °C [2].

Turning specifically to the amoeba N. fowleri: it is a moderate thermophile, able to reproduce up to about 46 °C [3], so spring temperature would be no problem. The growth media that I have seen for this amoeba often contain what's called Page's saline: 120 mg l-1 sodium chloride, 4 mg l-1 calcium chloride, 142 mg l-1 disodium hydrogen phosphate and 136 mg l-1 potassium dihydrogen phosphate. This is somewhat less saline than the spring water so depending on the tolerance of N. fowleri, might be a factor that limits growth. However, one study [4] shows that pathogenic N. fowleri are viable up to about 2% sodium chloride, so 650 ppm sodium is not likely to be a problem.

I hope that this helps with your question. For more information on amazing microbes just try "extremophiles" as a web search. Some good microbiology resources on the web are MicrobeWiki, Microbes.info and Microbe World.

Neil

References
[1] Halobacterium - MicrobeWiki
[2] Life in the hot seat - BBC Science News
[3] Naegleria fowleri - Medical Microbiology at NCBI
[4] Factors Affecting the Viability of Pathogenic Naegleria Species Isolated from Thai Patients (PDF) - Parasitology and Tropical Medicine Association of Thailand


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