Code:
$ perl -pe 's/\s*,\s*/,/g' infile
Sat Jul 23 16:10:03 EDT 2011,12345678,PROD,xyz_2345677,testuuyt,149693,abtryu
Jul 22 2011,NULL,PROD,yt12345,testuuytoy,162469,abtryu
Jul 22 2011,NULL,PROD,yt12345,testuuytoy,162469,abtryu
Jul 22 2011,NULL,PROD,yt12345,testuuytoy,162469,abtryu
Jul 22 2011,NULL,PROD,yt12345,testuuytoy,162469,abtryu
Jul 22 2011,NULL,PROD,yt12345,testuuytoy,162469,abtryu
Jul 22 2011,NULL,PROD,yt12345,testuuytoy,162469,abtryu