Ferroplasma thermophilum, a sort of extreme acidophilic archaea, which can synthesize intracellular cobalt ferrite nanocrystals, is investigated in this study. The nanocrystals were analyzed with ultrathin sections and transmission electron microscope, with the size of 20–60 nm, the number of more than 30 in each cell at average, which indicated that F. thermophilum can synthesize intracellular nanocrystals and also belongs to high-yield nanocrystals-producing strain. Intriguingly, the nanocrystals contain ferrite and cobalt characterized by EDS X-ray analysis, suggesting that both cobalt and ferrite are potentially contributed to the formation of nanocrystals. Moreover, under the different energy source culture conditions of FeSO₄ and CuFeS₂, the size and the morphology of the nanocrystals are different. It was also found that the higher initial Fe availability leads to an induced synthesis of larger nanocrystals and the lower oxidation-reduction potential (ORP) leads to an induced effect on the synthesis of nanocrystals with abnormal unhomogeneous size, which suggested that the higher initial Fe availability and the lower oxidation-reduction potential lead to a higher uptake efficiency of iron ions of F. thermophilum by iron and ORP gradient culture.

本研究研究了嗜铁亚铁，一种极端嗜酸古细菌，它可以合成细胞内钴铁氧体纳米晶体。用超薄切片和透射电子显微镜分析了纳米晶体，其大小为20-60 nm，平均每个细胞中有30多个，这表明嗜热链球菌可以合成细胞内纳米晶体，并且属于高产率的产生纳米晶体的菌株。有趣的是，纳米晶体包含以EDS X射线分析为特征的铁氧体和钴，这表明钴和铁氧体都可能对纳米晶体的形成有贡献。此外，在不同的能源培养条件下，FeSO ₄和CuFeS ₂，纳米晶体的尺寸和形态是不同的。还发现较高的初始Fe利用率导致较大的纳米晶体的诱导合成，较低的氧化还原电位（ORP）导致对具有异常不均匀尺寸的纳米晶体的诱导效应，这表明较高的初始Fe可用性和较低的氧化还原电位导致通过铁和ORP梯度培养提高嗜热链球菌铁离子的吸收效率。