  We present multi object optical spectroscopy of the galaxies in the
environment of 12 low-redshift (z < 0.5) quasars and of 11 inactive massive
galaxies chosen to match the properties of the quasar host galaxies to probe
physical association and possible events of recent star formation. The quasars
are selected from a sample of QSOs in the SDSS Stripe82 region for which both
the host galaxy and the large scale environments were previously investigated.
The new observations complement those reported in our previous works on close
companion galaxies of nearby quasars. For the whole dataset we find that for
about half (19 out of 44 ) of the observed QSOs there is at least one
associated companion galaxy. In addition to the new spectroscopic observations,
we add data from the SDSS database for the full sample of objects. We find that
the incidence of companion galaxies in the fields of QSO (17%) is not
significantly different from that of inactive galaxies (19%) similar to quasar
hosts in redshift and mass. Nevertheless, the companions of quasars exhibit
more frequently emission lines than those of inactive galaxies, suggesting a
moderate link between the nuclear activity and recent star formation in their
environments.
