A novel Gram-negative, aerobic, motile and short rod-shaped bacterium with exopolysaccharides production, designated as LZ-4^T, was isolated from cultivable phycosphere microbiota of harmful algal blooms-causing marine dinoflagellate Alexandrium catenella LZT09 which produces paralytic shellfish poisoning toxins. Strain LZ-4^T was able to use thiosulfate (optimum concentration 10 mM) as energy source for bacterial growth. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain LZ-4^T belonged to the genus Limnobacter, showing high 16S rRNA gene sequences similarities with L. thiooxidans DSM 13612^T (99.4%), L. humi NBRC 11650^T (98.2%) and L. litoralis NBRC 105857^T (97.2%), respectively. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between LZ-4^T and L. thiooxidans DSM 13612^T were 78.9 and 21.9%, respectively. Both values were far lower than the thresholds (95–96% for ANI and 70% for dDDH) generally accepted for new species delineation. The respiratory quinone of strain LZ-4^T was Q-8. The dominant cellular fatty acids were determined as summed feature 3 (C_16:1 ω6c/ω7c), summed feature 8 (C_18:1 ω6c/ω7c) and C_16:0. Polar lipids profile consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, two unidentified aminolipids and three unidentified polar lipids. The genomic DNA G+C content of strain LZ-4^T was 52.5 mol%. Based on polyphasic characterization, strain LZ-4^T represents a novel species of the genus Limnobacter, for which the name Limnobacter alexandrii sp. nov. is proposed. The type strain is LZ-4^T (=CCTCC AB 2019004^T =KCTC 72281^T).

从有害藻华的可培养菌圈菌群中分离出一种新型的革兰氏阴性，好氧，能动和短杆状产外多糖的细菌，命名为LZ-4 ^T，该菌群可引起海洋藻类鞭毛藻亚历山大藻（Alexandre catenella） LZT09，产生麻痹性贝类中毒毒素。LZ-4 ^T菌株能够使用硫代硫酸盐（最佳浓度为10 mM）作为细菌生长的能源。基于16S rRNA基因序列的系统发育分析表明，菌株LZ-4 ^T属于Limnobacter属，与硫氧化乳杆菌DSM 13612 ^T（99.4％）具有很高的16S rRNA基因序列相似性。NBRC 11650 ^T（98.2％）和利落乳NBRC 105857 ^T（97.2％）。平均核苷酸同一性（ANI）和数字DNA-DNA杂交（DDDH）值LZ-4之间^Ť和L.杆菌DSM 13612 ^Ť分别为78.9和21.9％之间。这两个值均远低于新物种划分所公认的阈值（ANI的95-96％和dDDH的70％）。LZ-4 ^T菌株的呼吸醌为Q-8。占主导地位的细胞脂肪酸确定为相加特征3（C _16：1 ω 6C / ω 7C），总结特征8（C _18：1 ω 6C / ω7c）和C _16：0。极性脂质谱由二磷脂酰甘油，磷脂酰乙醇胺，磷脂酰甘油，两种未鉴定的氨基脂质和三种未鉴定的极性脂质组成。应变LZ-4的基因组DNA G + C含量^Ť率为52.5摩尔％。基于多相表征，菌株LZ-4 ^T代表了Limnobacter属的一个新种，其名称为Limnobacter alexandrii sp。十一月 被提议。类型菌株为LZ-4 ^T（= CCTCC AB 2019004 ^T = KCTC 72281 ^T）。