Liu Guo-Hong, Yang Shang, Tang Rong, Xie Cheng-Jie, Zhou Shun-Gui
Agricultural Bio-Resources Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou, China.
Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China.
Front Microbiol. 2022 Feb 7;12:801462. doi: 10.3389/fmicb.2021.801462. eCollection 2021.
Five strictly anaerobic strains, designated RG2, RG3, RG10, RF4, and RG29, were isolated from paddy soils in China. Strains RG2, RF4, RG10, RG3, and RG29 grew at temperatures ranging 5-42°C and pH ranging 5.5-8.5. Strains RG2, RF4, RG3, and RG29 could tolerate NaCl up to 0-0.7% (w/v) while strain RG10 could tolerate NaCl up to 0-0.8% (w/v). The isolated strains showed the highest 16S rRNA gene sequence similarities to the type strains of Red111 and Red736. In phylogenetic (based on 16S rRNA gene sequence) and phylogenomic trees, strains clustered with the members of the genus Menaquinone-8 was the predominant quinone present in all strains. The major fatty acid profiles of all strains were C ω6, C, iso-C, and Summed Feature 3. The digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between the isolated strains and the closely related species were lower than the cutoff value (ANI 95-96% and dDDH 70%) for prokaryotic species delineation. Based on physiological, biochemical, and chemotaxonomic properties, strains RG2, RG10, and RF4 could easily be differentiated with the members of the genus . Additionally, all the isolated strains possessed clusters and catalytic compartments of nitrogenase. Based on the above results, the isolated five strains represent three novel species of the genus , for which the names sp. nov., sp. nov., and sp. nov. are proposed. The type strains are RG10 (= GDMCC1.2537 = KCTC 26318), RG2 (= GDMCC1.2536 = KCTC 25317), and RF4 (= GDMCC 1.2547 = KCTC 25316).
从中国稻田土壤中分离出五株严格厌氧菌株，分别命名为RG2、RG3、RG10、RF4和RG29。菌株RG2、RF4、RG10、RG3和RG29在5-42°C的温度范围和5.5-8.5的pH范围内生长。菌株RG2、RF4、RG3和RG29能够耐受高达0-0.7%（w/v）的NaCl，而菌株RG10能够耐受高达0-0.8%（w/v）的NaCl。分离出的菌株与Red111和Red736的模式菌株显示出最高的16S rRNA基因序列相似性。在系统发育（基于16S rRNA基因序列）和系统基因组树中，菌株与Men aquinone-8属的成员聚类，是所有菌株中存在的主要醌类。所有菌株的主要脂肪酸谱为C ω6、C、异-C和总和特征3。分离出的菌株与密切相关物种之间的数字DNA-DNA杂交（dDDH）和平均核苷酸同一性（ANI）值低于原核生物物种划分的临界值（ANI 95-96%和dDDH 70%）。基于生理、生化和化学分类学特性，菌株RG2、RG10和RF4很容易与该属的成员区分开来。此外，所有分离出的菌株都拥有固氮酶的簇和催化区室。基于上述结果，分离出的五株菌株代表该属的三个新物种，为此提出了新物种名称sp. nov.、sp. nov.和sp. nov.。模式菌株分别为RG10（=GDMCC1.2537 = KCTC 26318）、RG2（=GDMCC1.2536 = KCTC 25317）和RF4（=GDMCC 1.2547 = KCTC 25316）。
