Question

Why will we be testing the same potential germicides against two different kinds of bacteria? Do you expect to see any difference in the results between the two? Explain (Note: E. coli is gram negative, S epidermiclis is gram positive.)

Answer 1

Germicide is used to control the germs which are present on surfaces and kills them. Yes we test on both organisms like gram positive and gram negative bacteria because the permeability will be different.

Gram positive bacteria more susceptible to germicide and these molecules easily enter into cytoplasm and show it's action but in gram negative bacteria the entry of germicide will be very very low because of outer member it can not allow in to the cytoplasm and it will act as selective permeable membrane due to that the germicide can not kill or show efficiency in it's action.

Because of this reason they test in both organisms. Some germicides kill only gram positive bacteria know as narrow spectrum or narrow range germicides and some germicides kill both gram positive and gram negative bacteria know as broad spectrum germicides.