Sunday, July 26, 2009
P43

Microbial Production and Detection of Tetrodotoxin

Peter H. Yu and Chung Him Yu. Dept. of Applied Biology & Chemical Technology, Hong Kong Polytechnic University, Hung Hom, Hong Kong

In this study, the effect of phosphate and puffer fish extracts concentration on growth and TTX production of TTX-producing bacteria was investigated. For the effect of phosphate, five bacteria were studied on the effect of phosphate concentration, Raoultella terrigena, Bacillus cereus GC subgroup B, Serratia marcescens, Microbacterium arabinogalactanolyticum and Pseudomonas putida, while only the first two bacteria were studied on the effect of puffer fish extracts.

 Under high concentration of phosphate, the TTX production of some bacteria was repressed to half and growth of some bacteria was enhanced with two folds. It suggested phosphate could be involved in regulation in both growth and TTX production. Besides, the growth of Bacillus cereus GC subgroup B was improved by puffer fish extracts, especially the liver extract. Also, its TTX production was increased by the extracts. There could be some growth factor and unknown compounds affecting the cellular reactions in the extracts.

 Various detection methods, HPLC, ELISA and MALDI-TOF Mass Spectrometry, for TTX were compared. ELISA was much sensitive than HPLC. The lower detection limit of ELISA was about 1ng/ml TTX, which was lower than that of HPLC with 250 folds. However, the detected values by ELISA were much higher. It should be due to the interference with impurities and coexisted TTX analogs. In addition, the results of MALDI-TOF Mass Spectrometry further proved Raoultella terrigena was a TTX-producing bacterium.


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