Fahrbach Michael, Kuever Jan, Remesch Markko, Huber Birgit E, Kämpfer Peter, Dott Wolfgang, Hollender Juliane
Swiss Federal Institute of Aquatic Science and Technology, Eawag, Uberlandstr. 133, PO Box 611, CH-8600 Dübendorf, Switzerland.
Int J Syst Evol Microbiol. 2008 Sep;58(Pt 9):2215-23. doi: 10.1099/ijs.0.65342-0.
A denitrifying bacterium, designated strain FS(T), was isolated from anoxic digested sludge on oestradiol [17beta-oestra-1,3,5(10)-triene-3,17-diol] or testosterone (17beta-hydroxyandrost-4-en-3-one) as the sole source of carbon and energy with nitrate as the electron acceptor. Strain FS(T) represents the first known bacterium to grow anaerobically on both oestradiol (C-18) and testosterone (C-19). Steroidal hormones were degraded completely by nitrate reduction to dinitrogen monoxide, which was further reduced to dinitrogen in stationary-phase cultures. Gram-negative cells were slightly curved rods, 0.3-0.5 x 0.6-1.6 microm in size, motile, non-fermentative, non-spore-forming and catalase- and oxidase-positive, showing optimal growth at pH 7.0, 28 degrees C and 0.1% (w/v) NaCl. Beside steroidal hormones, the bacterium utilized only a narrow range of organic substrates with nitrate as the electron acceptor, including several fatty acids and glutamate. No aerobic or anaerobic growth occurred on liquid or solid complex media. Phylogenetic analysis of the 16S rRNA gene sequence showed that strain FS(T) has no known close relatives and represents a distinct lineage within the Gammaproteobacteria. Together with the genera Nevskia, Hydrocarboniphaga, Solimonas and Sinobacter (less than 88% 16S rRNA gene sequence similarity to strain FS(T)), it forms a phylogenetic cluster separated from the families Chromatiaceae, Ectothiorhodospiraceae and Xanthomonadaceae. The quinone system of strain FS(T) consisted exclusively of ubiquinone Q-8. The dominant polar lipids were diphosphatidylglycerol and phosphatidylethanolamine. Spermidine in combination with putrescine and traces of sym-homospermidine were the basic polyamines. The major fatty acids detected in testosterone- or heptanoate-grown cells were C(15:0) and C(17:1)omega8c, minor hydroxylated fatty acids were C(11:0) 3-OH and C(12:0) 3-OH. The G+C content of the DNA was 61.9 mol%. Based on the high 16S rRNA gene sequence divergence and different phenotypic properties from previously described gammaproteobacteria in combination with chemotaxonomic data, strain FS(T) is considered to represent a new genus and species, for which the name Steroidobacter denitrificans gen. nov., sp. nov. is proposed. The type strain of Steroidobacter denitrificans is FS(T) (=DSM 18526(T) =JCM 14622(T)).
从缺氧消化污泥中分离出一株反硝化细菌，命名为菌株FS(T)，该菌株以雌二醇[17β-雌甾-1,3,5(10)-三烯-3,17-二醇]或睾酮(17β-羟基雄甾-4-烯-3-酮)作为唯一碳源和能源，以硝酸盐作为电子受体。菌株FS(T)是已知的第一种能在雌二醇(C-18)和睾酮(C-19)上厌氧生长的细菌。甾体激素通过硝酸盐还原为一氧化二氮而被完全降解，在稳定期培养物中一氧化二氮进一步还原为氮气。革兰氏阴性菌为稍弯曲的杆菌，大小为0.3 - 0.5×0.6 - 1.6微米，具运动性，不发酵，不产芽孢，过氧化氢酶和氧化酶阳性，在pH 7.0、28℃和0.1% (w/v) NaCl条件下生长最佳。除甾体激素外，该细菌仅利用有限范围的有机底物并以硝酸盐作为电子受体，包括几种脂肪酸和谷氨酸。在液体或固体复合培养基上未出现好氧或厌氧生长。16S rRNA基因序列的系统发育分析表明，菌株FS(T)没有已知的近缘种，代表γ-变形菌纲内一个独特的谱系。它与涅夫斯基氏菌属、嗜烃菌属、土壤单胞菌属和中华杆菌属(16S rRNA基因序列与菌株FS(T)的相似性低于88%)一起，形成一个与着色菌科、外硫红螺菌科和黄单胞菌科分离的系统发育簇。菌株FS(T)的醌系统仅由泛醌Q-8组成。主要极性脂为双磷脂酰甘油和磷脂酰乙醇胺。亚精胺与腐胺以及微量的同型亚精胺是基本的多胺。在以睾酮或庚酸培养的细胞中检测到的主要脂肪酸为C(十五:0)和C(十七:1)ω8c，次要的羟基化脂肪酸为C(十一:0) 3-OH和C(十二:0) 3-OH。DNA的G+C含量为61.9 mol%。基于16S rRNA基因序列的高度差异以及与先前描述的γ-变形菌不同的表型特征，并结合化学分类学数据，菌株FS(T)被认为代表一个新属和新种，为此提出新属名反硝化甾体杆菌属(Steroidobacter)，新种名反硝化甾体杆菌(Steroidobacter denitrificans)。反硝化甾体杆菌的模式菌株为FS(T)(=DSM 18526(T)=JCM 14622(T))。
