Diversity and Biosynthetic Potential of Culturable Microbes Associated with Toxic Marine Animals

Abstract

Tetrodotoxin (TTX) is a neurotoxin that has been reported from taxonomically diverse organisms across 14 different phyla. The biogenic origin of tetrodotoxin is still disputed, however, TTX biosynthesis by host-associated bacteria has been reported. An investigation into the culturable microbial populations from the TTX-associated blue-ringed octopus Hapalochlaena sp. and sea slug Pleurobranchaea maculata revealed a surprisingly high microbial diversity. Although TTX was not detected among the cultured isolates, PCR screening identifiedsome natural product biosynthesis genes putatively involved in its assembly. This study is the first to report on the microbial diversity of culturable communities from H. maculosa and P. maculata and common natural product biosynthesis genes from their microbiota. We also reassess the production of TTX reported from three bacterial strains isolated from the TTX-containing gastropod Nassarius semiplicatus.

Production level of tetrodotoxin in Aeromonas is associated with the copy number of a plasmid

“…Genes encoding a hybrid PKS, NRPS enzyme, and AMT responsible for STX biosynthesis, were speculated to be involved in the pathway of TTX biosynthesis (Chau et al, 2011). Those genes are not unique for TTX biosynthesis, mostly locate in bacterial genomes as found in some TTXproducing bacteria (Chau et al, 2013), and were not found in the plasmid genome of pNe-1 in this study. The complete sequence of The melting temperature and the amplicon size were 82 C and 149 bp, respectively, for the target fragment (position 2252e2400).…”

“…In this study, TTX producing capability is shown to be associated with the copy number of a plasmid in Aeromonas strain Ne-1, suggesting the presence of TTX biosynthesis genes with at least one located in the genome of plasmid pNe-1. In a previous study (Chau et al, 2013), the genes encoding TTX biosynthesis enzymes, along with those associated with toxin regulation and transport, were speculated to be clustered in the genome, in a similar manner to saxitoxin biosynthesis pathways in bacteria (Kellmann et al, 2008a,b). Compared with bacterial genomes, plasmid genomes are relatively small and therefore easier to screen to identify TTX biosynthesis genes.…”

Bacterial diversity and tetrodotoxin analysis in the viscera of the gastropods from Portuguese coast

“…NRPSs are able to incorporate non-M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT proteogenic aminoacids with biosynthesis enzymes such as PKSs (Cane and Walsh, 1999;Chau et al, 2011), this (PKS-NRPS) enzyme complex are also involved in the biosynthesis of toxins (Bergmann et al, 2007;Schümann and Hertweck, 2007). The genes coding for the TTX biosynthesis enzymes are clustered on the genome of the toxin producers (Chau et al, 2013(Chau et al, , 2011.…”

Natural Voltage‐Gated Sodium Channel Ligands: Biosynthesis and Biology

“…[44] Studies on the frog Atelopus varius [45] and the fire-bellied newt Cynops pyrrhogaster [46] indicated that toxin levelsw ere non-detectable in captive-raised organisms,w hereas studies on the rough-skinned newt, Taricha granulosa, [47] have demonstrated an increase in toxin productionw hile held in captivity.T his ambiguity and irreproducibility has motivated efforts to pursue the isolation of tetrodotoxin-producing bacteria from the skin and tissues of host organisms. [39,48] While microorganisms from producing organisms have been successfully cultured on many occasions, the common result has been inconsistent production of 1 or related metabolites in isolated culture. [49] Most notably,s tudies by Noguchi have unequivocally demonstrated bacterial origins for tetrodotoxin production in the intestines pufferfish andx anthid crab by isolating gut microbes in pure culture and assessing them for production of 1.…”