Research of ureolytic bacteria and bio-concrete

Scientists have adapted the calcium carbonate production that microorganisms have made naturally for years to the concrete content and named this product Bio-Concrete. Thanks to the self-renewing bio-concrete, the cracks between concrete will be removed, the life of the concrete will be extended and the concrete production will be reduced indirectly. Calcium carbonate formation induced by urea hydrolysis is considered one of the main pathways of microbial-induced biomineralization. It has been revealed that the precipitation of carbonates induced by ureolytic bacteria is strongly associated with the activity of urease, the enzyme responsible for catalyzing urea hydrolysis. The higher the urease activity of a bacterium, the higher that bacteria will produce urea hydrolysis. As a by-product of urea hydrolysis, calcium carbonate will accumulate extracellularly. In this study, soil and sludge samples were collected from Ankara-Eskişehir high way and Salda Lake for the isolation of ureolytic bacteria capable of producing urease enzyme. By forming soil columns with the modified soil enrichment medium, ureolytic bacteria were allowed to grow, and then spread planting was made on modified urea agar from these enriched samples. Single colony isolation and purification was performed, considering the transformation from yellow to pink-purple color as an indicator of urease activity. 16S rDNA sequence analysis and fatty acid methyl esters (FAME) analysis were used for bacterial identification. Twenty three isolates with differing colony morphologies were determined as Enterobacter, Pseudomonas, Bacillus, Exiguobacterium, Cellulosimicrobium, Lysinibacillus and Marinilactibacillus, which are more than 99% similar, according to 16S rDNA sequence analysis. In conclusion, the isolates isolated and identified in this study are capable of producing urease enzyme and have the potential to be used in bio-concrete research. Keywords: Self-healing concrete, Bio-concrete, Ureolytic bacteria, Calcium carbonate, microbial induction, urease, urea hydrolysis