A Gram-negative, aerobic, non-symbiotic bacterium (AM1V30T) was isolated from the toxic dinoflagellate Alexandrium minutum AL1V. On the basis of 16S rRNA gene sequence similarity, strain AM1V30T was most closely related (97.4 % similarity) to the type strain of Hoeflea marina, which belongs to the family Phyllobacteriaceae within the order Rhizobiales of the class Alphaproteobacteria. A polyphasic approach was used to clarify the taxonomic position of strain AM1V30T. During the course of this study, a second species was described by others as belonging to the genus Hoeflea, namely Hoeflea phototrophica; it showed a somewhat higher level of 16S rRNA gene sequence similarity with respect to strain AM1V30T (98.2 %) and was also taken into account. The fatty acid profiles, physiological and biochemical data and DNA G+C content (59.7 mol%) support the classification of strain AM1V30T as a member of the genus Hoeflea. The characteristics of the novel strain were sufficiently distinct to indicate that it represents a separate species. To confirm this conclusion, DNA–DNA hybridizations were performed: low values (between 15.8 and 29.8 %) were obtained in all cases. Thus, AM1V30T represents a novel species within the genus Hoeflea, for which the name Hoeflea alexandrii sp. nov. is proposed. Strain AM1V30T (=CECT 5682T=DSM 16655T) is the type strain.
The toxic dinoflagellate Alexandrium minutum impairs the performance of oyster embryos and larvae