You can filter on the action before it is saved by using add_filter on
‘bp_blogs_activity_new_comment_action’ as shown in
bp-blogs-functions.php -> bp_blogs_record_comment()
Or you can filter before the action is displayed by using add_filter on
‘bp_get_activity_action’
Probably better to do the former because you can easily check post->post_type to see if it is ‘business’.
This shows how to adjust the activity action for the creation of a CPT:
http://buddypress.org/community/groups/how-to-and-troubleshooting/forum/topic/display-custom-post-types-in-activity-feed/
You should be able to adjust that to handle comments.