Ishii Satoshi, Ashida Naoaki, Ohno Hiroki, Segawa Takahiro, Yabe Shuhei, Otsuka Shigeto, Yokota Akira, Senoo Keishi
Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo, Japan.
Division of Environmental Engineering, Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido, Japan.
Int J Syst Evol Microbiol. 2017 Jun;67(6):1841-1848. doi: 10.1099/ijsem.0.001875. Epub 2017 Jun 20.
Thirty-nine denitrifying bacterial strains closely related to one another, represented by strains TSA40T and TSA66T, were isolated from rice paddy soils. Strains TSA40T and TSA66T were Gram-stain-negative, slightly curved rod-shaped, and motile by means of polar flagella. They were able to reduce nitrate, nitrite and nitrous oxide, but unable to fix atmospheric N2. While strain TSA66T was able to grow autotrophically by H2-dependent denitrification, strain TSA40T could not. Phylogenetic analysis suggested that they belong to the family Oxalobacteraceae, the order Burkholderiales in the class Betaproteobacteria. Major components in the fatty acids (C16 : 0, C17 : 0 cyclo, C18 : 1ω7c and summed feature 3) and quinone (Q-8) also supported the affiliation of strains TSA40T and TSA66T to the family Oxalobacteraceae. Based on 16S rRNA gene sequence comparisons, strains TSA40T and TSA66T showed the greatest degree of similarity to Herbaspirillum massiliense JC206T, Noviherbaspirillum malthae CC-AFH3T, Noviherbaspirillum humi U15T, Herbaspirillum seropedicae Z67T and Paucimonas lemoignei LMG 2207T, and lower similarities to the members of other genera. Average nucleotide identity values between the genomes of strain TSA40T, TSA66T and H. massiliense JC206T were 75-77 %, which was lower than the threshold value for species discrimination (95-96 %). Based on the 16S rRNA gene sequence analysis in combination with physiological, chemotaxonomic and genomic properties, strains TSA40T (=JCM 17722T=ATCC TSD-69T) and TSA66T (=JCM 17723T=DSM 25787T) are the type strains of two novel species within the genus Noviherbaspirillum, for which the names Noviherbaspirillum denitrificans sp. nov. and Noviherbaspirillum autotrophicum sp. nov. are proposed, respectively. We also propose the reclassification of Herbaspirillum massiliense as Noviherbaspirillum massiliense comb. nov.
从稻田土壤中分离出39株彼此密切相关的反硝化细菌菌株，以TSA40T和TSA66T菌株为代表。TSA40T和TSA66T菌株革兰氏染色阴性，呈微弯杆状，借助极生鞭毛运动。它们能够还原硝酸盐、亚硝酸盐和一氧化二氮，但不能固定大气中的N2。虽然TSA66T菌株能够通过依赖氢气的反硝化作用自养生长，但TSA40T菌株不能。系统发育分析表明，它们属于草酸杆菌科，β-变形菌纲伯克霍尔德氏菌目。脂肪酸（C16 : 0、C17 : 0环丙烷、C18 : 1ω7c和特征性总和3）和醌（Q-8）的主要成分也支持TSA40T和TSA66T菌株属于草酸杆菌科。基于16S rRNA基因序列比较，TSA40T和TSA66T菌株与马赛草螺菌JC206T、麦芽新草螺菌CC-AFH3T、潮湿新草螺菌U15T、草螺菌Z67T和勒莫因寡养单胞菌LMG 2207T的相似度最高，与其他属成员的相似度较低。TSA40T、TSA66T菌株与马赛草螺菌JC206T基因组之间的平均核苷酸同一性值为75-77 %，低于物种区分阈值（95-96 %）。基于16S rRNA基因序列分析并结合生理、化学分类和基因组特性，TSA40T（=JCM 17722T=ATCC TSD-69T）和TSA66T（=JCM 17723T=DSM 25787T）菌株是新草螺菌属内两个新物种的模式菌株，分别命名为反硝化新草螺菌（Noviherbaspirillum denitrificans sp. nov.）和自养新草螺菌（Noviherbaspirillum autotrophicum sp. nov.）。我们还建议将马赛草螺菌重新分类为马赛新草螺菌（Noviherbaspirillum massiliense comb. nov.）。
