低Mg/Ca条件下丛毛单胞菌HJ-1菌株诱导文石的形成

Curvibacter sp. strain HJ-1 induced the formation of aragonite under the condition of low Mg/Ca ratio

摘要:

[目的]为了探讨细菌对碳酸盐矿物种类和形态的影响。[方法]本文利用丛毛单胞菌HJ-1菌株进行了持续50 d的培养实验。在实验过程中，对细菌数量、沉淀物重量、培养液中Ca²⁺和Mg²⁺浓度等进行了动态监测。利用扫描电子显微镜对矿物形态进行了观察，并利用X-射线衍射仪对矿物成分进行测定。[结果]丛毛单胞菌HJ-1菌株具有显著的诱导碳酸盐矿物沉淀的能力，碳酸盐矿物的重量随着培养时间的延长而逐渐增加。X-射线衍射结果表明，形成的碳酸盐沉淀主要由文石和高镁方解石组成，其中文石的最高含量达86%。上述矿物在形态上复杂多样，主要有杆状、柱状、哑铃形、球状和板状以及不规则状和鳞片状集合体。[结论]通常，在Mg/Ca≤2并且有微生物参与的条件下极少形成文石。本文在Mg/Ca为2，不含碳酸根离子的培养基中培养HJ-1菌株的过程中发现了文石。作者认为，低Mg/Ca条件下文石的形成主要与HJ-1菌株分泌较多的胞外多糖有关。

关键词:丛毛单胞菌;文石;高镁方解石;胞外多糖;生物矿化

Abstract:

[Objective] To study the effects of bacteria on the species and morphology of carbonate minerals. [Methods] We conducted a series of cultural experiments in the medium with initial Mg/Ca ratio of 2 but without carbonate ion using Curvibacter sp. strain HJ-1 for 50 days. During the cultivation, bacterial density, precipitate quantities, calcium and magnesium concentration were determined. The morphologies of precipitated carbonates were observed using scanning electron microscopy, and mineral species of carbonate were determined by X-ray diffraction. [Results] Strain HJ-1 could induce the precipitation of carbonate minerals, the quality of carbonate gradually increased with the incubation time. XRD patterns showed that the mineral precipitates consisted of high-Mg calcite and aragonite. The percentage of aragonite in the precipitates was up to 86%. The morphology of carbonate minerals was multiform, including rod-shaped, dumbbell-shaped, spherical, tabular, as well as irregular and flake. [Conclusions] The formation of aragonite under the condition of low Mg/Ca ratio has a close correlation with extracellular polysaccharide secreted by Curvibacter sp. strain HJ-1.

Key words:Curvibacter sp.;Aragonite;High-Mg calcite;Extracellular polysaccharide;Biomineralization