Primary Study Of Relations Between Bacillus Cereus Spores And Gold Mineral Resource

The Quaternary soil microorganism, Bacillus cereus, is reported as an effective indicator of the underlying gold mineralization. This paper presented particularly the colony-counting method of Bacillus cereus in gold deposit of Shewu Mountain in Jiayu county, Hubei province. Many factors affecting counting results, such as colony morphology and positive bacteria category on mannitol-yelk-polymoxin agar medium (MYP), centrifugation and dilution in sample dealing process were analysed in detail, and an improved enumerative method was acquired.The experiments of interaction between Au3+,Ag+,Cu2+, Zn2+, Mn2+ and soil B.cereus isolated from gold mining regions and background regions were carried out to validate the relationship between gold contents and the spore numbers of B.cereus and to solidify the theoretical basis of this bio-exploration method. Results showed: The heavy metal ions with a specific high concentration in culture solutions is capable of prohibiting the growth of B.cereus and promoting the sporulation, which will result in the occurrence of an abnormal enrichment of B.cereus spore counts in soils over the mineralized regions. Therefore, the cluster of high spore counts, in turn, can serve as an exploration tool to the subsurface mineral deposits.Bio-sorption and tolerance of Bacillus cereus to the heavy metals such as Au3+, Ag+, Cu2++ Zn2+were studied in this paper. Emphasis was laid on the interaction between Au3+ and B. cereus. Results showed that the metallic sensitivity of B. cereus varied among different metals. The 48h-EC50 were 0.09 μ g mL-1,0.6 μ g mL-1 ,0.08mg mL-1 and 0.02 mg mL-1, respectively for Au3+, Ag+, Cu2+ and Zn2+ respectively. The metallic sensitivity of bacterial strains also changed with bacterial growing phases. The toxic order of the 4 heavy metals to B. cereus was Au3+,> Ag+> Zn2+> Cu2+. The bio-sorption of B. cereus spores on Au3+ was a rapid process, independent on temperature with an optimum pH between 5~6. The bio-absorptive rate and bio-absorptive capacity would reach 92.3% and 240 mg · g-1 respectively under the conditions of ρ i(Au3+)=1 mg · mL-1, P b(spore)=2 mg · L-1, T=30℃, pH at 5.0, and absorptive time=30min.