Puffer fish, Takifugu niphobles, collected from the Hong Kong coastal waters 
were screened for tetrodotoxin-producing bacteria. A Gram-negative, 
non-acid-fast, non-sporing and rod shaped bacterial strain (designated as 
gutB01) was isolated from the intestine of the puffer fish and was shown to 
produce tetrodotoxin (TTX). Based on the Microbial Identification (MIDI) and 
16S-23S rDNA internal transcribed spacer (ITS) phylogenetic analysis, the strain 
was identified as Raoultella terrigena. The TTX production ability of the strain 
was confirmed by mouse bioassay, ELISA and mass spectrometry (MALDI-TOF). Our 
results reiterate that the TTX found in puffer fish was likely produced by the 
associated bacteria and TTX are widely produced amongst a diversity of bacterial 
species.