DNA homology was used to reveal that all isolates of
A. salmonicida
were highly related, i.e. 96-106% homology, when
hybridized against A. salmonicida subsp. salmonicida
. It was opined that A. salmonicida subsp. masoucida
and some atypical isolates did not warrant separate
subspecies status, because they were regarded as variants
of other well-recognized groups. Also as a result of genotypic
analyses, it was reported that typical and atypical
isolates of A. salmonicida were very closely related, with
minimal divergence. Using DNA:DNA re-association,
it was concluded that typical A. salmonicida were
recovered in a homogeneous group, whereas the atypical
representatives were more diverse . From numerical
taxonomy and DNA:DNA hybridization, similar conclusions
resulted regarding the homogeneity of typical
isolates of A. salmonicida . However using 16S
rRNA sequencing techniques, it was reported that subspecies
achromogenes and masoucida were indistinguishable,
and only differed from subspecies salmonicida by
two bases