S2 Appendix -

Our previous studies indicate the abundant and diverse presence of yet-to-be-cultured microorganisms in the micropore-filtered fractions of various environmental samples. Here, we isolated a novel bacterium (designated as strain TMPK1T) from a 0.45-μm-filtered soil suspension by using a gel-filled microwell array device comprising 900 microwells and characterized its phylogenetic and physiological features. This strain showed low 16S rRNA gene sequence identities (<91%) and low average nucleotide identity values (<70%) to the closest validly described species, and belonged to a novel-family-level lineage within the order Rhodospirillales of Alphaproteobacteria. Strain TMPK1T exhibited small cell sizes (0.08–0.23 μm3) and had a high cyclopropane fatty acid content (>13%), and these characteristics were differentiated from other Rhodospirillales bacteria. A comprehensive habitability search using amplicon datasets suggested that TMPK1T and its close relatives are mainly distributed in soil and plant-associated environments. Based on these results, we propose that strain TMPK1T represents a novel genus and species named Roseiterribacter gracilis gen. nov., sp. nov. (JCM 34627T = KCTC 82790T). We also propose Roseiterribacteraceae fam. nov. to accommodate the genus Roseiterribacter.

我们此前的研究表明，各类环境样品的微孔过滤组分中存在丰度高、多样性丰富的未培养微生物（yet-to-be-cultured microorganisms）。本研究中，我们使用包含900个微孔的凝胶填充微孔阵列装置，从经0.45 μm滤膜过滤的土壤悬浮液中分离得到一株新型细菌（命名为菌株TMPK1^T），并对其系统发育与生理特征进行了表征。该菌株与最近的有效描述物种的16S rRNA基因序列相似性（<91%）及平均核苷酸一致性（average nucleotide identity, ANI）数值（<70%）均较低，隶属于α-变形菌纲（Alphaproteobacteria）红螺菌目（Rhodospirillales）下的一个全新科级系统发育支系。菌株TMPK1^T的细胞体积较小（0.08~0.23 μm³），环丙烷脂肪酸（cyclopropane fatty acid）含量较高（>13%），这些特征均与红螺菌目其他细菌存在显著差异。通过扩增子数据集开展的全面生境分布分析表明，菌株TMPK1^T及其近缘类群主要分布于土壤及植物相关环境中。基于上述结果，我们提议将菌株TMPK1^T定为新属新种，命名为纤细玫瑰土杆菌（Roseiterribacter gracilis gen. nov., sp. nov.），其模式菌株保藏号为JCM 34627^T = KCTC 82790^T。我们同时提议建立玫瑰土杆菌科（Roseiterribacteraceae fam. nov.）以容纳玫瑰土杆菌属（Roseiterribacter）。