47
Isolation
Material from diseased tissues was inoculated onto TSA, TSA plus 5 % (v/v) goat
blood, and BHIA with incubation at 25 °C for 3 days (Chen et al. 2012 ). In a subsequent study, brain, kidney and material from a musculoskeletal lesion was inoculated onto Mueller Hinton agar supplemented with 5 % (v/v) sheep blood with
incubation at 26 °C for 48 h when the predominant white-tan colony type was subcultured (Khoo et al. 2014 ).
Pathogenicity
Chen et al. ( 2012 ) examined pathogenicity in tilapia, and reported LD 50 values following i.p. injection the isolates of 10
2 –10
5 CFU/ml. Pathogenicity was not confi rmed in laboratory based infectivity experiments by Khoo et al. ( 2014 ).
Lactococcus piscium
Characteristics of the Disease
The disease condition encompasses lactobacillosis or pseudokidney disease of rainbow trout.
Characteristics of the Pathogen
The taxonomy of the Group N streptococci has undergone extensive revision. On
the basis of 23S rRNA:DNA hybridization and superoxide dismutase studies, the
genus Lactococcus was defi ned to accommodate these organisms. A group of fi sh
Box 2.10: Lactococcus lactis subsp. lactis
Cultures comprise Gram-positive oval nonmotile cocci that grow at 45 °C and
in 6.5 % (w/v) sodium chloride. Arginine dihydrolase, leucine arylamidase
and pyrrolidonyl arylamidase are produced, but not alkaline phosphatase,
ß-glucuronidase, H 2 S, catalase or oxidase. Nitrates are not reduced. The
Voges Proskauer reaction is positive. Acid is produced from amygdalin, mannitol, ribose and sucrose, but not from L-arabinose, glycogen, lactose, raffi -
nose or sorbitol. Citrate is not utilized. Aesculin and blood (α-haemolysis) are
attacked, but not sodium hippurate or urea (Chen et al. 2012 ; Khoo et al.
2014 ). Sequence homology of the 16S rRNA/16S SSU rDNA gene revealed
100 % similarity with Lactococcus lactis subsp. lactis in the GenBank data
base (Chen et al. 2012 ; Khoo et al. 2014 ).
Streptococcaceae Representatives
Isolation
Material from diseased tissues was inoculated onto TSA, TSA plus 5 % (v/v) goat
blood, and BHIA with incubation at 25 °C for 3 days (Chen et al. 2012 ). In a subsequent study, brain, kidney and material from a musculoskeletal lesion was inoculated onto Mueller Hinton agar supplemented with 5 % (v/v) sheep blood with
incubation at 26 °C for 48 h when the predominant white-tan colony type was subcultured (Khoo et al. 2014 ).
Pathogenicity
Chen et al. ( 2012 ) examined pathogenicity in tilapia, and reported LD 50 values following i.p. injection the isolates of 10
2 –10
5 CFU/ml. Pathogenicity was not confi rmed in laboratory based infectivity experiments by Khoo et al. ( 2014 ).
Lactococcus piscium
Characteristics of the Disease
The disease condition encompasses lactobacillosis or pseudokidney disease of rainbow trout.
Characteristics of the Pathogen
The taxonomy of the Group N streptococci has undergone extensive revision. On
the basis of 23S rRNA:DNA hybridization and superoxide dismutase studies, the
genus Lactococcus was defi ned to accommodate these organisms. A group of fi sh
Box 2.10: Lactococcus lactis subsp. lactis
Cultures comprise Gram-positive oval nonmotile cocci that grow at 45 °C and
in 6.5 % (w/v) sodium chloride. Arginine dihydrolase, leucine arylamidase
and pyrrolidonyl arylamidase are produced, but not alkaline phosphatase,
ß-glucuronidase, H 2 S, catalase or oxidase. Nitrates are not reduced. The
Voges Proskauer reaction is positive. Acid is produced from amygdalin, mannitol, ribose and sucrose, but not from L-arabinose, glycogen, lactose, raffi -
nose or sorbitol. Citrate is not utilized. Aesculin and blood (α-haemolysis) are
attacked, but not sodium hippurate or urea (Chen et al. 2012 ; Khoo et al.
2014 ). Sequence homology of the 16S rRNA/16S SSU rDNA gene revealed
100 % similarity with Lactococcus lactis subsp. lactis in the GenBank data
base (Chen et al. 2012 ; Khoo et al. 2014 ).
Streptococcaceae Representatives