Study On The Formation Mechanism Of Carbonate Minerals Induced By Curvibacrer Sp.Strain HJ-1

The formation of carbonate minerals induced by microorganism is of great importance in many respects.Studying the formation mechanism of bacteria induced carbonate can enrich the soil formation theory,control the heavy metal pollution of water and soil,and provide scientific clues for fixation of atmospheric CO2.In recent years,the use of microbial induced carbonate mineral for the conservation of deteriorated ornamental stone also shows a bright future.At present,microbial mineralization has made many achievements,but there are still some mechanism is not clear.In view of the important research significance of microbial mineralization,and in order to solve the shortcomings in current research,we used curvibacrer sp.which was isolated from the soil and its extracted partial secretions to conduct a series of experiments,respectively.Control experiments were also performed at the same time.In this paper,we tried to clarify the species and morphological changes of carbonate minerals under the action of bacteria,and provide scientific evidences for deep understanding of the formation mechanism of carbonate minerals.Bacteria density,pH,electrical conductivity,content of extracellular polysaccharide,activity of carbonic anhydrase,quantity of precipitate,Ca2+ and Mg2+ concentrations in the media were determined during the experiments.The mineral morphologies were observed by scanning electron microscopy(SEM),and the mineral species were determined by X-ray diffraction.The main findings are as follows:1)The bacterial strain HJ-1 has a significant ability to induce the precipitation of carbonate minerals,and the quantity of carbonate minerals gradually increases over incubation time.The weight of precipitate significantly negatively correlated with the EC,Ca2+ and Mg2+ concentrations,with r = 0.92,0.92,and 0.93,respectively.2)X-ray diffraction patterns showed that the mineral precipitates consisted of high-Mg calcite and aragonite by the actions of HJ-1 strain and EPSac3)The morphology of carbonate minerals was multiformed under the action of HJ-1 strain and EPS,including rod-shaped,dumbbell-shaped,spherical,tabular andirregular.There are only spherical and plate shape with the action of CA.4)The EPS may primarily promote the formation of carbonate minerals by providing nucleation templates.The formation of dumbbell-shaped minerals may be controlled by the carboxyl groups of EPS and Mg2+.The presence of EPS promote the interaction of Mg2+ and the calcie lattice,and Mg2+ is conducive to the formation of aragonite.5)CA mainly promoted the formation of carbonate minerals by catalyzing the hydration reaction of CO2,which increased the formation rate of carbonate minerals by 1.7 times.