:g/_pattern_/s/^/#/g

will comment out lines containing _pattern_ (if # is your comment character)

Another way of doing this is with normal commands instead of text substitution:

:%g/912150\|912147\|912145\|912157\|912155\|912151/norm I//

Note: there is a trailing space in this code block

swap g with v at the beginning and it will comment out lines that don't match the pattern.