I have been characterising a new strain of Streptomyces and was wanting to compare it to other similar alkaliphilic strains of Streptomyces. I have read of figures as high as 11.5 but the manuscript does not mention if this pH was measured once or continuously over the 4-5 days period of growth.
Studies on Antibiotics Produced at High Alkaline pH : Michikatsu Sato, Teruhiko Beppu & Kei Arima . Agricultural and Biological Chemistry Volume 47, 1983 - Issue 9 . Are there any other measurements higher than this ?
Streptomyces have their pH optimum at 6.5-8.0. Most antibiotics are produced by Streptomyces at neutral pH (7.0). However, I am familiar with two factors that make pH generalization for Streptomyces difficult. The first is the species or strain of the Streptomyces and second, the medium in which the bacterium grows. Yes, I have read about the pH 11.5 too, but not the one you suggested. Documents are attached for details. I think it's proper that you fill the gap you have identified in the course of your research.
Thanks Maurice. From our current work we observe that sterilisation decreases the pH of the media 1 or 2 units. This subsequently decreases on a daily basis. The pH of the most alkaline media diminishes rapidly unless you add a suitable buffer. The optimum pH is also influenced by the growth media as you had suggested. Reading the attached papers I cannot find a reference to the measurement of the pH after the agar was set in the paper by Kontro et al 2005. I am not sure of the buffer system they used but in our experience an unbuffered system, say pH 10.5 will decreases rapidly within a matter of 4 days to pH7 . In this instance, Kontro et al 2005, incubated the Streptomyces on the media 16 days ! I also cannot find the mention to the addition of buffer in the second paper by Semu and Akishule . The authors incubated their organism for at least 7 days . Without any intervening measurements it is hard to tell if the pH is dropping. In our experience, it was usual that the pH decreased in both SFM media and ISP2 media (unbuffered) over a similar time period. In the final paper by Hamid et al 2015 , there was a range of pH media used but i could not find any reference to continuous measurement of pH over the 4-5 days of the experiment.
please follow these articles:
1. http://www.nrcresearchpress.com/doi/abs/10.1139/m92-016
2. http://jb.asm.org/content/183/10/3184.short
3. http://mic.microbiologyresearch.org/content/journal/micro/10.1099/00221287-137-7-1715
4. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1472-765X.2005.01727.x
Thanks Jai Ghosh. I wanted to compare my findings with other research because I am new to the field of extereme microbiology. Originally I had measured my solid media only once and therefore the data showed a very high pH reading. Subsequently I measured the pH as my Streptomyces grew and realized that a) the pH of solid media will drop on sterilization b) unless the media is buffered, the pH of the media will drop rapidly over several days, c) even when buffered the pH will drift slightly over a period of a few days, d) it is important to choose the correct buffer at high pH levels (i.e. pH 9-13).
It is a very wrong way to do research. See, every researcher has his or her objectives clearly defined and so yours too. Comparisons of others results, more than often, misleads you or confuses you and the extreme is it may throw you out of your line of research. Do not compare your findings with others.What is best done is to establish what you have found agrees with the reported ones or not. In either case you should have your justifiable explanations ready.
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