) Ability to grow in different pH: Principle: - pH is defined as logarithm to the base 10 of the inverse of the hydrogen ion concentration (or preferably H+ ion activity). It is also the negative logarithm to the base 10 of H+ ion activity. This test was carried out on ISP2 media. pH was adjusted to different ranges of 5, 6, 7, 8, 9 and 10. Duplicate slants were prepared for each strain of each range. After the incubation of 10-12 days readings were taken for each strain.