Phenotypic and molecular typing of Vibrio harveyi isolates and their pathogenicity to tiger shrimp larvae.
OBJECTIVE
The objective of the present study was to identify the biotype(s) and molecular type(s) of Vibrio harveyi associated with pathogenicity in tiger shrimp (Penaeus monodon) larvae.


RESULTS
Five luminescent and four nonluminescent V. harveyi isolates were subjected to phenotyping and random amplified polymorphic DNA (RAPD) fingerprinting, and pathogenicity testing to P. monodon mysis. Four isolates induced 34-41% mortality of P. monodon mysis when challenged at the rate of 10(6) CFU ml(-1) within 60 h. Sucrose-fermenting biotypes of V. harveyi appeared to be associated with pathogenicity to larval shrimp. Higher temperature and salinity appeared to play a role on the onset of vibriosis and mortality in the challenged larval shrimp. Pathogenic isolates of V. harveyi could be demarcated as revealed by their clustering in the dendrogram constructed based on the RAPD fingerprints.


CONCLUSIONS
Nonluminescent V. harveyi also appear to be important aetiological agents of vibriosis of shrimp larvae. Sucrose-fermenting biotypes are likely to be pathogenic. High temperature may trigger onset of vibriosis.


CONCLUSIONS
Biotyping of V. harveyi isolates and looking for traits, such as ability to ferment sucrose may be helpful in identifying the pathogenic forms, and such approach requires to be investigated further with larger number of isolates.
Alavandi
S V
SV
Aquatic Animal Health Division, Central Institute of Brackishwater Aquaculture, Indian Council of Agricultural Research, Chennai, Tamil Nadu, India. svalavandi@yahoo.com
Manoranjita
V
V
Vijayan
K K
KK
Kalaimani
N
N
Santiago
T C
TC
D000818:Animals; D015373:Bacterial Typing Techniques; D006863:Hydrogen-Ion Concentration; D007814:Larva / Q000382:microbiology; D033561:Penaeidae / Q000382:microbiology*; D010641:Phenotype; D019105:Random Amplified Polymorphic DNA Technique; D012965:Sodium Chloride / Q000494:pharmacology; D013696:Temperature; D014733:Vibrio / Q000145:classification* / Q000472:pathogenicity; D037521:Virulence Factors / Q000096:biosynthesis
D037521:Virulence Factors; D012965:Sodium Chloride