Calcite and Vaterite Biosynthesis by Nitrate Dissimilating Bacteria in Carbonatogenesis Process under Aerobic and Anaerobic Conditions

Abstract

This study deals with 16S-rDNA identified bacteria, Lysinibacillus sp., Raoultella sp., and Streptomyces sp. capable of precipitating CaCO₃ through nitrate reduction aerobically and anaerobically. The produced CaCO₃ crystals were analyzed using XRD, EDX, FTIR, TGA and SEM. The results showed that the carbonatogenic bacteria served as nucleation sites for CaCO₃ precipitation with distinct variation in polymorph and morphology; reflecting strain-specific property. Notably, the amount of precipitated CaCO₃ recorded 3.27 (aerobic), 1.55 (anaerobic), 4.15 (aerobic), 3.75 (aerobic) and 1.87 (anaerobic) g/100 mL of strains Lysinibacillus sp., Streptomyces sp. and Raoultella sp., respectively, after 240 h of incubation. The study of changes in media chemistry during carbonatogenesis process revealed positive correlation between bacterial growth, nitrate reductase activity, pH, EC, Ca²⁺ depletion, amount of deposited CaCO₃ and NO₃⁻ consumption. Therefore, the applications of these bacterial strains, which were employed for the first time in carbonatogenesis process, are promising in the environmental, biomedical and civil engineering fields.

Keywords:

• Streptomysetes
• Raoultella
• Lysinibacillus
• nitrate reductase
• microbial induce CaCO₃ precipitation
• nitrate reduction

Acknowledgment

This research was conducted at Genetic Engineering and Biotechnology Research Institute, City of Scientific Research and Technological Applications, Burg elarab city, Alexandria, Egypt

Disclosure statement

The authors declare no competing or financial interests.