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 °C (optimum, 25–33 °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 ω7 c and/or C 18 : 1 ω6 c ), summed feature 3 (C 16 : 1 ω7 c and/or C 16 : 1 ω6 c ) 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 ).