MLST is considered to be one of the promising methods for species
delineation (Chen et al., 2010; Martino et al., 2011; Urwin and
Maiden, 2003). The phylogeny of the six diseased turtle isolates was analyzed
together with other 93 Aeromonas isolates by constructing a
neighbor-joining tree based on the 3084 bp concatenated sequences
of six loci (Fig. 2). The tree revealed two major phylogroups, one of
which contained only the Aeromonas schubertii reference strain, while
the second one harbored all other 92 isolates that formed three main
clusters, corresponding to A. sobria–A. veronii complex, A. hydrophila
complex and A. caviae–A. media complex, respectively. All six diseased
turtle isolates fell into the A. sobria–A. veronii complex, with the isolates
from the same farm located in the same branch, whereas those from
different farms occupying distinct but genotypically related branches.
MLST demonstrated these diseased turtle isolates belonged to A.
sobria–A. veronii complex.