436
Flavobacterium succinicans
The organism has been associated with rainbow trout in recirculation systems in the
USA. From these fi sh, the presence of Fla. branchiophilum and Fla. succinicans
was determined by sequencing of the 16S rRNA gene (Good et al. 2015 ).
Flectobacillus roseus
Characteristics of the Disease
The disease, coined fl ectobacillosis, was recognized in captive rohu ( Labeo rohita)
in India. Fish displayed discolouration, loss of mucus and scales in the region of the
caudal peduncle, and tail rot (Adikesavalu et al. 2015 ).
Isolation
Inocula from the caudal peduncle were streaked onto cytophaga agar supplemented
with 5 mg of neomycin/ml and 200 IU of polymyxin B/ml with incubation at 30 °C
for 48 h leading to the development of pale pink-rose colonies (Adikesavalu et al.
2015 ).
Characteristics of the Pathogen
Box 7.14: Flectobacillus roseus
Cultures are pale pink-rose pigmented, round, convex and smooth with entire
edges, and contain Gram-negative nonmotile, non-fermentative long thin
rods, that produce catalase, α- and ß-galactosidase, ß-glucoronidase, α- and
ß-glucosidase, oxidase and phosphatase, but not H 2 S, lysine or ornithine
decarboxylase. Urea is not degraded. Nitrate reaction is variable. Citrate is not
utilized. Sequencing of the 16S rRNA gene reveals a homology of 96 % with
Flectobacillus roseus in GenBank (Adikesavalu et al. 2015 ), which is below
the level for an acceptable identifi cation (Adikesavalu et al. 2015 ).
7 Flavobacteria and Cytophagas
Flavobacterium succinicans
The organism has been associated with rainbow trout in recirculation systems in the
USA. From these fi sh, the presence of Fla. branchiophilum and Fla. succinicans
was determined by sequencing of the 16S rRNA gene (Good et al. 2015 ).
Flectobacillus roseus
Characteristics of the Disease
The disease, coined fl ectobacillosis, was recognized in captive rohu ( Labeo rohita)
in India. Fish displayed discolouration, loss of mucus and scales in the region of the
caudal peduncle, and tail rot (Adikesavalu et al. 2015 ).
Isolation
Inocula from the caudal peduncle were streaked onto cytophaga agar supplemented
with 5 mg of neomycin/ml and 200 IU of polymyxin B/ml with incubation at 30 °C
for 48 h leading to the development of pale pink-rose colonies (Adikesavalu et al.
2015 ).
Characteristics of the Pathogen
Box 7.14: Flectobacillus roseus
Cultures are pale pink-rose pigmented, round, convex and smooth with entire
edges, and contain Gram-negative nonmotile, non-fermentative long thin
rods, that produce catalase, α- and ß-galactosidase, ß-glucoronidase, α- and
ß-glucosidase, oxidase and phosphatase, but not H 2 S, lysine or ornithine
decarboxylase. Urea is not degraded. Nitrate reaction is variable. Citrate is not
utilized. Sequencing of the 16S rRNA gene reveals a homology of 96 % with
Flectobacillus roseus in GenBank (Adikesavalu et al. 2015 ), which is below
the level for an acceptable identifi cation (Adikesavalu et al. 2015 ).
7 Flavobacteria and Cytophagas