The Researches On Biomineralization Of Calcium And Strontium Ions Induced By Microorganisms As Well As Interfacial Regulation Mechanism

The role of microorganis ms as well as calc ium and stront ium io ns molar ratio(C a²⁺/Sr²⁺) on biomineralizat ion for calc ium stront ium carbonate were studied in this research through the route comb ing t he theoretical know ledge and exper imenta l method of microbiology and mineralo gy. Based on analyt ical compar ison for the ro le of these two factors in biomineralizat ion, we can not only understand the bio logica l mechanis ms for the for mat ion of carbonate minerals, but also he lp us to understand the interaction mechanis m and process of these two factors in carbonate biomineralizat ion. The influence s of microorganis ms on minera l phase, crystal model, crystal morphology and growth orientat ion were ana lyzed by us ing X- ray diffractio n?XRD?, Four ier infrared spectroscopy?FTIR? and scanning e lectron microscope?SEM? and other modern testing means according to methods of interaction between b iologica l addit ives and mineral. The ana lys is focused on inter face interaction and regulat ion role of microbia l cell sur face funct ion groups in b iomineralizat ion.The results are as follows:?1? It was easier to form calc ite crysta ls and aragonite crystals under higher calc ium and stront ium ion concentrat ion cond it ions, respective ly, for bla nk groups. The microbes could induce the carbonate to for m calc ite under high stront ium concentrat ion condit ions, the induct ion ability was as fo llows: Bacillus mucitaginosus > Deinococcus radiodurans > Escherichia coli > Saccharom yces cerev isiae; But Bacillus subt ili was unable to induce the for matio n of calcite under such conditions, but it could change the morphology of aragonite.?2? Under the culture condit io ns, microbes could induce calc ium and stront ium ions into the carbonate crystal lattice : when calc ium ion concentration was higher, Escherichia coli, Saccharom yces cerev isiae and Bacillus mucitaginosus induced more ca lcium ions subst itut ing stront ium ions in the calc ium carbonate crystal latt ice; when stront ium calc ium ion concentration was cons istent, only Bacillus m ucitaginosus and Saccharomyces cerevisiae induced more calc ium ions entering into the crystal latt ice of calc ite, whereas Escherichia coli induced more stront ium io ns entering into the crystal latt ice of aragonite; under higher concentratio ns of stront ium ions, Deinococcus radiodurans, Escherichia coli and Saccharom yces cerev isiae ind uced more calc ium into the aragonite crystal latt ice, while Deinococcus radiodurans and Escherichia coli induced more strontium ions entering into the calcite crystal lattice.?3? When ca lcium ion concentrat ion is higher, the microbial ce ll freeze-dried powder induced to form ca lcite by inhib it ing t he for mat ion of aragonite; when calc ium strontium ions ratio was 1:1, only Deinococcus radiodurans could still induce to form pure calc ite. When calc ium stront ium ratio was 4:1, Deinococcus radiodurans freeze- dr ied powder, Bacillus subt ili freeze-dried powder, Escherichia coli and Saccharom yces cerev isiae powder induced more strontium ions enter ing into calc ite crystal latt ice; When ca lc ium stront ium ratio was 1:1, Saccharomyces cerev isiae freeze- dried powder induced more stront ium ions enter ing into the aragonite crystal la tt ice; when ca lc ium stront ium ratio was 1:4, only Bacillus subt ilis freeze-dried powder could induce more strontium ions entering into the aragonite crystal lattice.?4? Five kinds of microbes could induce more stront ium io ns entering into the calc ite crysta ls after shield ing sur face funct ion groups under high calc ium ion concentrat ion condit ions and changed the crystal morpholo gy except for Bacillus subt ilis under condit ions for C a²⁺ / Sr²⁺ = 1: 1; When the stront ium ion concentrat ion was higher, Deinococcus radiodurans, Bacillus subt ilis and Saccharomyces cerevisiae could induce more calc ium ions enter ing into aragonite crystals after shielding surface function groups.?5? When the Ca²⁺ / Sr²⁺ = 4:1, the carboxyl and ester group of Deinococcus radiodurans cell wa lls and the amino, carboxyl, ester groups of Bacillus subt ilis, Saccharomyces cerev isiae cell and Escherichia coli cell wa lls could induce the format ion o f calcite t hrough inter face interaction and inhib ited the format ion of aragonite; when the Ca²⁺ / Sr²⁺ was 1:1, the amino group and ester group of Bacillus subt ilis cell wa lls and the a mino, carboxyl, ester groups of Deinococcus radiodurans bacteria cell wa lls induced the format ion o f calcite by inhib it ing the formation of aragonite.In summary, t he calcium carbonate and stront ium carbonate minerals induced by five k inds of microorganis ms showed obvious differences in cr ystal morpholo gy, phase and size. This indicated that microorganis ms have certain regulat ion effect on the for mat ion of carbonate crystals dur ing bio mineralizatio n. The cell walls of microorganis ms are rich in amino, carboxyl and ester funct ion groups, which could control crystal morpho logy, phase and size of the biominerals through t he inter face interaction. The research results provide some certain theoretica l basis for explor ing carbonate biomineralizat ion mechanis m induced by the microorganism.