Reverse string columns in a pandas subset dataframe

I have the following dataframe.

    ID  LOC Alice   Bob  Karen
0   1   CH  9|5 6|3 4|4
1   2   ES  1|1 0|8 2|0
2   3   DE  2|4 6|6 3|1
3   4   ES  3|9 1|2 4|2

Alice and Bob columns contain string values. I want to reverse the strings in these columns conditional on the value of another column. For example, where LOC==ES, reversing the strings in the corresponding columns would look like:

    ID  LOC Alice   Bob   Karen
0   1   CH  9|5 6|3 4|4
1   2   ES  1|1 8|0 0|2
2   3   DE  2|4 6|6 3|1
3   4   ES  9|3 2|1 2|4

Is there a fast way to perform this operation on all matching rows in a csv file with thousands rows?

Thank you.