Abstract
A PCR amplification method for P 3 helix region of ribonuctease P (RNase P) RNA gene was developed for the rapid identification of Vibrio harveyi. The P 3 helix is comprised of tandem repeat of a palindromic sequence, and the number of the repeats is different between Vibrio core species. V. harveyi was distinguished from the other Vibrio core species with the PCR, since only the species had 4 repeats in the P 3 helix whereas the other Vibrio core species were 3 to 1; V. parahaemolyticus, V. campbeffii, V. carchariae, V. natriegens, and V. pelagius had 3 repeats; and V. alginolyticus and V. proteolyticus had 1 repeat. Although one hundred and thirty strains isolated from vibrio-infected black tiger shrimp (Penaeus monodon) and their culture pond, and healthy shrimp and their ponds were applied to the PCR amplification, only one strain was identified as V. harveyi. Most of the strains showed the size of 3 repeats in the PCR amplification. The nucleotide sequences of RNase P RNA gene and its upstream region indicated that the three representative bacterial strains isolated from the vibrio-infected shrimp were V. campbellii.
