Biodiversity Study of Intracellular Bacteria Closely Associated with Paralytic Shellfish Poisoning Dinoflagellates Alexandrium tamarense and A. minutum

Paralytic shellfish poisoning (PSP) toxins are potent environmental neurotoxins mainly produced by marien dinoflagellates. Alexandrium spp. are the most abundant and widespread producer of saxitoxin (STX). Currently, the evolutionary history that resulted in the curious cross-kingdom distribution of STX-synthesis remained unclear. However, the increasing number of findings of toxin-producing bacteria in dinoflagellate supports the hypothesis of the bacterial origin of PSP toxins. Addtionally, evidence that there are specific symbiosis bacterial taxa associated with phytoplankton indicates the presence of specific selective mechanisms between them, and implies that the symbiosis bacteria have some vital functions to the benefit of the dinoflagellates. Culture-independent high-throughput pyrosequencing analysis is able to provide a thorough description of microbiota community in environmental samples, which also helps to reveal their potential function. This paper aims to demonstrate the biodiversity of the bacteria closely associated with two toxic dinoflagellate strains, A. tamarense and A. minutum using the pyrosequencing method.