Isolation and characterization of novel iron-oxidizing bacteria that grow at circumneutral pH
Isolation and characterization of novel iron-oxidizing bacteria that grow at circumneutral pH
复制标题
DOI：
10.1128/aem.63.12.4784-4792.1997
复制
发表时间：
1997-12-01
影响因子：
4.4
通讯作者：
Moyer, C
中科院分区：
文献类型：
--
作者：
Emerson, D;Moyer, C
采用凝胶稳定梯度法，利用Fe2+和O-2的相反梯度，从密歇根州含Fe2+的中性地下水中分离和鉴定了两种新的铁氧化细菌。获得了两种不同的增菌培养物，每种培养物中的细胞都在缺氧-缺氧界面处的凝胶中以明显的铁锈色带生长。细胞与氢氧化铁紧密结合。对这两种培养物进行多次连续稀释，分离出两株无菌菌株ES-1和ES-2。根据(I)单个菌落在10(-7)(Es-2)和10(-8)(Es-1)稀释度下在试管中的生长情况；(Ii)均匀的细胞形态，即ES-1是可移动的细长的、弯曲的或S形状的杆状，ES-2是较短的弯曲的杆状；(Iii)在异养培养基上不生长。ES-1菌株在FeS上生长至10(8)个/ml，倍增时间为8h，ES-2菌株在FeCO3上生长至5×10(7)个/ml，倍增时间为12.5h。这两个菌株都不能在没有Fe2+的情况下生长，也不能在葡萄糖、丙酮酸、醋酸盐、锰或硫化氢作为电子供体的情况下生长。氧微电极的研究表明，两株菌都生长在梯度的缺氧-缺氧界面上，并在较高的O-2浓度下追踪到O-2的最小值，表明它们是微需氧菌。在系统发育上，这两个菌株在伽马变形杆菌中形成了一个新的谱系。它们彼此之间的亲缘关系非常密切，与PVB OTU 1和SPB OTU 1的亲缘关系也同样密切，PVB OTU 1是一种来自太平洋洛伊希海山富铁热液喷口系统的系统型，SPB OTU 1是从西伯利亚永久冻土中获得的一种系统型。它们最近的栽培近亲是嗜麦芽窄食单胞菌。总而言之，这一证据表明，ES-1和ES-2是先前未被开发的一组假定有利于结石的单细胞氧化铁细菌的成员。
A gel-stabilized gradient method that employed opposing gradients of Fe2+ and O-2 was used to isolate and characterize two new Fe-oxidizing bacteria from a neutral pH, Fe2+-containing groundwater in Michigan. Two separate enrichment cultures were obtained, and in each the cells grew in a distinct, rust-colored band in the gel at the oxic-anoxic interface. The cells were tightly associated with the ferric hydroxides. Repeated serial dilutions of both enrichments resulted in the isolation of two axenic strains, ES-1 and ES-2. The cultures were judged pure based on (i) growth from single colonies in tubes at dilutions of 10(-7) (ES-2) and 10(-8) (ES-1); (ii) uniform cell morphologies, i.e., ES-1 was a motile long thin, bent, or S-shaped rod and ES-2 was a shorter curved rod; and (iii) no growth on a heterotrophic medium. Strain ES-1 grew to a density of 10(8) cells/ml on FeS with a doubling time of 8 h. Strain ES-2 grew to a density of 5 x 10(7) cells/ml with a doubling time of 12.5 h. Both strains also grew on FeCO3. Neither strain grew without Fe2+, nor did they grow with glucose, pyruvate, acetate, Mn, or H2S as an electron donor. Studies with an oxygen microelectrode revealed that both strains grew at the oxic-anoxic interface of the gradients and tracked the O-2 minima when subjected to higher O-2 concentrations, suggesting they are microaerobes. Phylogenetically the two strains formed a novel lineage within the gamma Proteobacteria. They were very closely related to each other and were equally closely related to PVB OTU 1, a phylotype obtained from an iron-rich hydrothermal vent system at the Loihi Seamount in the Pacific Ocean, and SPB OTU 1, a phylotype obtained from permafrost soil in Siberia. Their closest cultivated relative was Stenotrophomonas maltophilia. In total, this evidence suggests ES-1 and ES-2 are members of a previously untapped group of putatively lithotrophic, unicellular iron-oxidizing bacteria.