Comparison of bacterial communities associated with Prorocentrum donghaiense and Karenia mikimotoi strains from Chinese coastal waters

Abstract

The dinoflagellates Karenia mikimotoi (toxic) and Prorocentrum donghaiense (non-toxic) have caused serious blooms in Chinese coastal waters. Although many studies have investigated the mechanisms underlying the harmful algal blooms of these two species, research on bacterial communities associated with K. mikimotoi and P. donghaiense is still limited. In this study, the composition of associated bacterial communities of K. mikimotoi and P. donghaiense were investigated in cultured strains. The genera with the highest relative abundance in K. mikimotoi and P. donghaiense cultures were Balneola and Marinobacter respectively. There were 26 genera specifically present in K. mikimotoi cultures, including Alteromonas, Methylophaga and Thalassospira. Sixteen genera were specifically present in P. donghaiense cultures, including an unclassified genus belonging to Nannocystaceae, Loktanella and Roseivirga. Various aromatic hydrocarbons capable of degrading bacteria were detected in the K. mikimotoi culture, but not in the P. donghaiense culture; this may contribute to the toxicity or toxin synthesis of K. mikimotoi. The results of this study provide further insights into bloom formation mechanisms and elucidate the different characteristics of K. mikimotoi and P. donghaiense blooms.