Mechanism of Biomineralization Induced by Bacillus subtilis J2 and Characteristics of the Biominerals
Mechanism of Biomineralization Induced by Bacillus subtilis J2 and Characteristics of the Biominerals
复制标题
枯草芽孢杆菌J2诱导生物矿化的机理及生物矿物质的特性
DOI：
10.3390/min9040218
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发表时间：
2019-04-01
期刊：
影响因子：
2.5
通讯作者：
Yan, Huaxiao
中科院分区：
文献类型：
--
作者：
Han, Zuozhen;Wang, Jiajia;Yan, Huaxiao
微生物诱导的生物矿化作用已成为碳酸盐沉积学领域的研究热点，但其作用机制仍有待深入研究。本研究利用枯草芽孢杆菌J2(GenBank MG575432)在镁钙摩尔比分别为0、3、6、9、12的条件下诱导碳酸钙矿物的沉淀。枯草芽孢杆菌J2细菌释氨可使pH升高，但释放的氨气仅使pH升高至8.25。碳酸酐酶也被产生来催化二氧化碳的水合，这个过程释放出碳酸盐和碳酸氢根离子，这不仅增加了pH，而且增加了碳酸盐的过饱和度。当镁钙摩尔比为0时，形成的生物矿物为球状、拉长形、哑铃形和不规则的斜方解石；当镁钙摩尔比为3时，生物矿物为方解石和文石，随着培养时间的延长，方解石的重量比从26.7%下降到15.6%，文石的重量比从73.3%增加到84.4%。在较高的镁钙摩尔比下，生物矿物为文石，随着镁钙摩尔比的增加，文石的结晶度和热稳定性降低。FTIR结果表明，生物矿物表面和内部存在C-O-C、N-H、C=O、O-H和C-H等有机官能团。对枯草杆菌J2细菌超薄切片的HRTEM-SAED分析表明，EPS涂层上生长或吸附了晶体结构较差的纳米矿物。枯草杆菌J2菌株的胞外多糖含有丰富的谷氨酸和天冬氨酸，在碱性条件下可以去质子化，吸附钙、镁离子，使胞外多糖成为成核中心。本研究为进一步了解微生物诱导生物矿化的机理提供了参考。
Biomineralization induced by microorganisms has become a hot spot in the field of carbonate sedimentology; however, the mechanisms involved still need to be explored. In this study, the bacterium Bacillus subtilis J2 (GenBank MG575432) was used to induce the precipitation of calcium carbonate minerals at Mg/Ca molar ratios of 0, 3, 6, 9, and 12. Bacillus subtilis J2 bacteria released ammonia to increase pH, but the ammonia released only made the pH increase to 8.25. Carbonic anhydrase was also produced to catalyze the hydration of carbon dioxide, and this process released carbonate and bicarbonate ions that not only increased pH but also elevated carbonate supersaturation. The biominerals formed at a Mg/Ca molar ratio of 0 were spherulitic, elongated, dumbbell-shaped, and irregularly rhombohedral calcite; at a Mg/Ca molar ratio of 3, the biominerals were calcite and aragonite, the weight ratio of calcite decreased from 26.7% to 15.6%, and that of aragonite increased from 73.3% to 84.4% with increasing incubation time. At higher Mg/Ca molar ratios, the biominerals were aragonite, and the crystallinity and thermal stability of aragonite decreased with increasing Mg/Ca molar ratios. FTIR results showed that many organic functional groups were present on/within the biominerals, such as C-O-C, N-H, C=O, O-H, and C-H. HRTEM-SAED examination of the ultra-thin slices of B. subtilis J2 bacteria showed that nano-sized minerals with poor crystal structure had grown or been adsorbed on the EPS coating. The EPS of the B. subtilis J2 strain contained abundant glutamic acid and aspartic acid, which could be deprotonated in an alkaline condition to adsorb Ca2+ and Mg2+ ions; this made EPS act as the nucleation sites. This study may provide some references for further understanding of the mechanism of biomineralization induced by microorganisms.