Pfennig’s medium contains ammonium chloride, potassium phosphate and potassium chloride amongst other things.
I have seen other culture media which also contain these things and there is a note on one which says that “potassium chloride provides essential ions”. Why are these additional ions needed when they are already present in the form of ammonium chloride and potassium phosphate?
I apologize if this question is too basic. It arises because I have never studied biology, but I have developed a pressing need to culture some of the organisms which grow in a facultative pond, for reasons which are too eccentic to explain.
Thanks in advance. I find it quite disappointing that the forum doesn’t allow posters to thank respondents. People are responding to questions here on their own time I imagine, so why is common courtesy outlawed?