Phenomenon And Mechanism Of Biomineralization Induced By Sporosarcina Pasteurii

Biomineralization is the process by which inorganic minerals are generated from a biochemical reaction in living organism systems.It has been observed in organisms covering from bacteria to mammalian.In the past decade,due to the high activity,Urease mediated calcite biomineralization has been widely implemented into applications from bio-architecture to biomedicine.Herein,as research model,Sporosarcina pasteurii was studied for microbiologicallly induced precipitation of various metallic cation and the mechanism was analyzed at the molecular level.A new method by which Sporosarcina pasteurii mediated biomineralization was investigated was developed.Biomineralizatoin was performed in a chemical clearly defined solution.Through comparing the biomineralization of various metallic cation,it was found that the morphology of formed crystal fell into two classes,block shape and grainy shape.And Fe and Ca were further investigated in more detail.The parameters which affect the Sporosarcina pasteurii mediated biomineralization including concentration of urea molecule or ion and cell density were studied thoroughly.It was found that the ferric crystal formed on the surface of cell was magnetic.Both of the Fe and Ca mineral were analyzed by SEM.For study of the molecular mechanism,RT-PCR assay was estimated to analyze the expression of urea degradation related genes.Firstly,the method of RT-PCR including RNA extraction from Sporosarcina pasteurii and electrophoresis was optimized.Furthermore,it was found that expression level of the key gene were different with or without the Urea supplemented in the media during cell culture.This result indicate that there is Urea responding regulation on gene expression of urea metabolism in Sporosarcina pasteurii.Moreover,DNA structure encoding the whole urease cluster from Sporosarcina pasteurii was redesigned and de novo synthesized for introducing the biomineralization function into E.coli strain BL21(DE3).It will be a powerful tool for further study of Urease mediated biomineralization in the future.In sum,the Sporosarcina pasteurii mediated biomineralization,not only the experiment method but also the mechanism,was investigated thoroughly in this study.We believe that the result of this study will improve the understanding of Sporosarcina pasteurii mediated biomineralization.