443
Characteristics of the Pathogen
From these traits, Hikida et al. ( 1979 ) proposed that the organism belonged in an
as yet undescribed species of Flexibacter, for which the name of Fle. marinus was
mooted. Subsequently, Wakabayashi et al. ( 1986 ) formally proposed the name of
Fle. maritimus to accommodate the pathogen. Independently, Reichenbach ( 1989 )
proposed the name of Cyt. marina for the same organism. However, the organism
was subsequently reclassifi ed in a newly described genus Tenacibaculum, as T.
maritimum (Suzuki et al. 2001 ). The intraspecifi c diversity of 29 fresh isolates and
3 reference cultures has been addressed using RAPDs with the outcome that two
principle (and distinct serological) groups were recognised, of which one contained
all the cultures from sole and gilthead sea bream, and the second group comprised
isolates from Atlantic salmon, turbot and yellowtail. Interestingly, the reference
strains were not recovered with the fresh isolates, and may refl ect the problem of
using archived cultures which have been long removed from their natural habitat
(Avendaño-Herrera et al. 2004c ). Further publications by this group (AvendañoHerrera et al. 2004d ; 2005b ) defi ned three serotypes, i.e. O1, O2 and O3 which were
regarded as host specifi c, with serotype O1, O2 and O3 comprising isolates from
sole and gilthead sea bream, turbot and sole, respectively.
The nonmotile strain described by Rahman et al. ( 2014 ) formed slightly yellow
round colonies with rhizoidal edges, and was not pathogenic for Japanese fl ounder
when challenged by immersion. There was reduced adhesion ability to glass surfaces in shaking broth cultures and to the body surface of Japanese fl ounder. By gel
immunodiffusion, the cell-surface antigen associated with gliding strains was
absent, although the potential virulence traits, i.e. chondroitinase and gelatinase
activities, were present (Rahman et al. 2014 ) .
Box 7.19: Tenacibaculum maritimum
A very homogeneous group (Bernardet et al. 1994 ), with cultures forming
pale yellow fl at, thin colonies, containing strictly aerobic Gram-negative rods
of 2–30 × 0.5 μm in size, which occasionally form fi laments of up to 100 μm
in length. In older cultures, cells become spherical (~0.5 μm in diameter).
Microcysts do not occur. Gliding movement is a characteristic feature of all
isolates, and a non-gliding strain has been reported from diseased puffer fi sh
( Takifugu rubripes ) in Japan (Rahman et al. 2014 ). Catalase and oxidase are
produced, but not H 2 S or indole. Nitrates are not reduced. The methyl red test
is negative. Casein, gelatin, tributyrin and tyrosine are degraded, but not aesculin, agar, cellulose, chitin starch or urea. Growth occurs from 14.6–34.3 °C,
and at pH 6–9. There are requirements for potassium chloride and sodium
chloride. Acid is not produced from arabinose, cellobiose, glucose, lactose,
mannitol, raffi nose, salicin, sucrose or xylose. Isolates are capable of lysing
dead cells of Aer. hydrophila, Edw. tarda, Esch. coli and V. anguillarum, but
not Bacillus subtilis. The G + C ratio of the DNA is 31.3–32.5 moles %
(Hikida et al. 1979 ; Wakabayashi et al. 1986 ). All isolates share a common
antigen (Wakabayashi et al. 1984 ).
Tenacibaculum maritimum (= Flexibacter maritimus = Cytophaga marina)
Characteristics of the Pathogen
From these traits, Hikida et al. ( 1979 ) proposed that the organism belonged in an
as yet undescribed species of Flexibacter, for which the name of Fle. marinus was
mooted. Subsequently, Wakabayashi et al. ( 1986 ) formally proposed the name of
Fle. maritimus to accommodate the pathogen. Independently, Reichenbach ( 1989 )
proposed the name of Cyt. marina for the same organism. However, the organism
was subsequently reclassifi ed in a newly described genus Tenacibaculum, as T.
maritimum (Suzuki et al. 2001 ). The intraspecifi c diversity of 29 fresh isolates and
3 reference cultures has been addressed using RAPDs with the outcome that two
principle (and distinct serological) groups were recognised, of which one contained
all the cultures from sole and gilthead sea bream, and the second group comprised
isolates from Atlantic salmon, turbot and yellowtail. Interestingly, the reference
strains were not recovered with the fresh isolates, and may refl ect the problem of
using archived cultures which have been long removed from their natural habitat
(Avendaño-Herrera et al. 2004c ). Further publications by this group (AvendañoHerrera et al. 2004d ; 2005b ) defi ned three serotypes, i.e. O1, O2 and O3 which were
regarded as host specifi c, with serotype O1, O2 and O3 comprising isolates from
sole and gilthead sea bream, turbot and sole, respectively.
The nonmotile strain described by Rahman et al. ( 2014 ) formed slightly yellow
round colonies with rhizoidal edges, and was not pathogenic for Japanese fl ounder
when challenged by immersion. There was reduced adhesion ability to glass surfaces in shaking broth cultures and to the body surface of Japanese fl ounder. By gel
immunodiffusion, the cell-surface antigen associated with gliding strains was
absent, although the potential virulence traits, i.e. chondroitinase and gelatinase
activities, were present (Rahman et al. 2014 ) .
Box 7.19: Tenacibaculum maritimum
A very homogeneous group (Bernardet et al. 1994 ), with cultures forming
pale yellow fl at, thin colonies, containing strictly aerobic Gram-negative rods
of 2–30 × 0.5 μm in size, which occasionally form fi laments of up to 100 μm
in length. In older cultures, cells become spherical (~0.5 μm in diameter).
Microcysts do not occur. Gliding movement is a characteristic feature of all
isolates, and a non-gliding strain has been reported from diseased puffer fi sh
( Takifugu rubripes ) in Japan (Rahman et al. 2014 ). Catalase and oxidase are
produced, but not H 2 S or indole. Nitrates are not reduced. The methyl red test
is negative. Casein, gelatin, tributyrin and tyrosine are degraded, but not aesculin, agar, cellulose, chitin starch or urea. Growth occurs from 14.6–34.3 °C,
and at pH 6–9. There are requirements for potassium chloride and sodium
chloride. Acid is not produced from arabinose, cellobiose, glucose, lactose,
mannitol, raffi nose, salicin, sucrose or xylose. Isolates are capable of lysing
dead cells of Aer. hydrophila, Edw. tarda, Esch. coli and V. anguillarum, but
not Bacillus subtilis. The G + C ratio of the DNA is 31.3–32.5 moles %
(Hikida et al. 1979 ; Wakabayashi et al. 1986 ). All isolates share a common
antigen (Wakabayashi et al. 1984 ).
Tenacibaculum maritimum (= Flexibacter maritimus = Cytophaga marina)