Aerobic denitrification and biomineralization by a novel heterotrophic bacterium, Acinetobacter sp. H36

A novel aerobic denitrification and biomineralization strain H36 was isolated from the Qu Jiang artificial lake. Based on phylogenetic characteristics, the isolated strain was identified as Acinetobacter species. Strain H36 was confirmed to have the ability to perform simultaneous denitrification and biomineralization. Results showed the strain H36 had the capability to completely reduce 96.29% of NO3−-N and 78.59% of Ca2 + over 112 h under aerobic condition. Response surface methodology (RSM) analysis demonstrated the highest removal ratio of Ca2 + was 74.24% with hardness concentration of 350 mg/L, pH of 8.5, organic concentration of 0.75 g/L and inoculum size of 15%. The highest removal ratio of nitrate was 77.00% with hardness concentration of 350 mg/L, pH of 7.5, organic concentration of 0.75 g/L and inoculum size of 10%. Besides, X-ray diffraction (XRD) analysis showed calcium carbonate could be formed in the process of biomineralization.