The reason of Kloxo-MR using mysql 5.5 because until this time don't know why mysql 5.1 not able to start/restart. Sadly, centalt remove their mysql 5.5 in centos 6 and php52s still compile under mysql 5.5.
Need recompile php52s with dependencies to mysql55 (from IUS) rather than mysql 5.5 (from CentAlt).