Curvibacter sp. HJ-1菌株诱导碳钙镁石的形成

Curvibacter sp. strain HJ-1 induces the formation of huntite

摘要:

【背景】无论是在自然界还是在模拟实验产物中，碳钙镁石均是比较罕见的碳酸盐矿物类型。【目的】探究在实验过程中意外发现的碳钙镁石的成因，在对包括本文在内的所有有关碳钙镁石的实验条件进行综合分析的基础上，进一步探究此类矿物的形成机理。【方法】在Mg/Ca为5.0条件下对Curvibacter sp. HJ-1菌株进行了为期30 d的培养，定期测定细菌数量、pH值、Ca2+和Mg2+浓度，利用扫描电子显微镜对沉淀物形态进行观察，利用X-射线衍射仪对矿物成分进行测定。【结果】随着培养时间的延长，细菌培养液的pH值总体上呈现逐渐升高的趋势，而Ca2+和Mg2+浓度呈现逐渐降低的趋势。对于无菌对照实验(CK)，上述3项指标均保持稳定。在HJ-1菌株实验体系中，第8天开始形成碳钙镁石，至实验结束(第30天)一直以该矿物为主。在CK体系中自始至终未形成任何矿物。随着培养时间的延长，X-射线衍射图谱上显示的碳钙镁石晶面数有逐渐增多的趋势，这意味着其结晶程度趋于变好。【结论】Mg/Ca≥2.0、钙和镁离子浓度之和介于0.03?0.07 mol/L、饱和指数>1.95并存在微生物的溶液环境比较有利于碳钙镁石的形成。

关键词:生物矿化，碳钙镁石，Curvibacter sp.，饱和指数

Abstract:

[Background] Whether in the nature or in experimental products, huntite is rare carbonate mineral. [Objective] Explore the cause of the unexpected discovery of the huntite during the culture experiments, on the basis of comprehensive analysis of the condition of all experiments related to huntite, to further explore the formation of the minerals. [Methods] A series of cultural experiments in the medium with Curvibacter sp. strain HJ-1 and initial Mg/Ca ratio of 5.0 were carried out for 30 days. During the incubation, cell density, pH, concentration of Ca2+ and Mg2+ in the medium were determined according to the scheduled time. Mineral type was identified by X-ray diffraction (XRD) and the morphology was observed by scanning electron microscopy (SEM). [Results] The pH value of the medium with strain HJ-1 increased, while the concentrations of Ca2+ and Mg2+ decreased gradually with incubation time. For control experiments (CK) without bacteria, the above three indicators were stable. The precipitation of huntite began to form on the 8th day and continued to the end of the experiment (30th day), while any minerals were not formed in the CK system. XRD patterns indicated that the number of crystal planes of huntite is increasing gradually. This means that the crystallinity of huntite tends to be better with incubation time. [Conclusion] The culture with Mg/Ca ratio of ≥2.0, the total concentration of calcium and magnesium ions of 0.03?0.07 mol/L, saturation index above 1.95 and presence of microorganisms is favorable for the formation of huntite.

Key words:biomineralization, huntite, Curvibacter sp., saturation index