I have to grow E.coli in a minimal media but I don't have M9 salt to prepare minimal media. Is there any other way to make minimal media for this particular strain?
If you mean a true minimal medium then you need to provide the inorganic elements that are needed for growth, such as ammonia, sodium, phosphate, carbon, chlorine, magnesium etc (plus of course an organic energy source). Those are the critical components in the minimal medium. It is certainly possible to use a solution buffered with Tris or Mops instead of phosphate buffer such as M9, but you still need to add the other salts to provide the essentials. If you use a complex medium with tryptone or peptone or yeast extract, then those inorganics are present in the macromolecules from the complex media.