Effects of monosaccharides and protein in extracellular polymeric substances of Klebsiella aerogenes on crystalline forms of CaCO3 crystals
(1. Key Discipline Laboratory for National Defence of Biotechnology in Uranium Mining and Hydrometallurgy, University of South China, Hengyang 421001, China;
2. School of Metallurgy and Environment, Central South University, Changsha 410083, China)
2. School of Metallurgy and Environment, Central South University, Changsha 410083, China)
Abstract: A strain of Klebsiella aerogenes (K. aerogenes) capable of decomposing calcium acetate for CaCO3 biomineralization was screened, and the optimum conditions for producing the maximum mass of CaCO3 crystals induced by Klebsiella aerogenes were found to be 0.25 mol/L calcium acetate, 4% inoculum level, and pH 7. Following that, the monosaccharides and proteins contained in the extracellular polymeric substances (EPS) of Klebsiella aerogenes were identified. The effects of additional identified monosaccharide and proteins on the crystalline form conversion of CaCO3 crystals were investigated, and the additional monosaccharides were found to promote the crystalline form conversion of CaCO3 crystals from vaterite to calcite. Specifically, adding 1.00 g/L glucuronic acid was observed to enhance the conversion of crystalline phases of CaCO3 crystals to calcite completely after 5 d. Meanwhile, additional catalase was observed to contribute to the regular morphology of CaCO3 crystals without affecting their crystalline phases. The results indicate that the additional glucuronic acid influences the crystalline forms of CaCO3 crystals significantly.
Key words: uranium; CaCO3 crystal; microbially induced CaCO3 precipitation; extracellular polymeric substances; Klebsiella aerogenes