Saccharospirillum alexandrii sp. nov., isolated from the toxigenic marine dinoflagellate Alexandrium catenella LZT09

A Gram-stain-negative, strictly aerobic, non-motile and non-pigmented spirillum, designated strain LZ-5(T), was isolated from cultures of the paralytic shellfish poisoning (PSP) toxin-producing marine dinoflagellate Alexandrium catenella LZT09 collected from the Zhoushan sea area in the East China Sea during an algal bloom. The isolate grew at 4-40 degrees C (optimum. 25-33 degrees C) and pH 5.0-9.0 (optimum, 7.5) in the presence of 0.5-10% (w/v) NaCl (optimum. 4.0%). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain LZ-5(T )clearly belonged to the genus Saccharospirillum of the family Saccharospirillaceae. Strain LZ-5(T) shared highest 16S rRNA gene sequence similarity with Saccharospirillum impatiens EL-105(T) (98.9%), Saccharospirillum mangrovi HK-33(T) (97.2%), Saccharospirillum correiae CPA1(T) (96.8%), Saccharospirillum salsuginis YIM-Y25(T) (96.8%) and Saccharospirillum aestuarii IMCC 4453(T )(95.1 %). The average nucleotide identity and in silico DNA-DNA hybridization between strain LZ-5(T )and the two most closely related Saccharospirillum strains, S. impatiens EL-105(T) and S. mangrovi HK-33(T) , were 82.2 and 19.3%, and 72.2 and 13.2%, respectively. The predominant respiratory quinone of strain LZ-5(T) was Q-8, and the major fatty acids were summed feature 8 (C-18:1 omega 7c and/or C-18:1 omega 6c), summed feature 3 (C-16:1 omega 7c and/or C-16:1 omega 6c) and C-16:0. The polar lipids of strain LZ-5(T) were diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE). phosphatidylcholine (PC), glycolipid (GL), two unidentified glycophospholipids (GPLs), three unidentified aminophospholipids (APLs) and two unidentified lipids. The genomic DNA G+C content was 57.2 mol%. On the basis of this polyphasic characterization, strain LZ-5(T) represents a novel species of the genus Saccharospirillum, for which the name Saccharospirillum alexandrii sp. nov. is proposed. The type strain is LZ-5(T) (=KCTC 62460(T) =CCTCC AB2017232(T)).