Characterization of Two Urease-Producing and Calcifying Bacillus spp. Isolated from Cement

Abstract

Two bacterial strains designated as CT2 and CT5 were isolated from highly alkaline cement samples using the enrichment culture technique. On the basis of various physiological tests and 16S rRNA sequence analysis, the bacteria were identified as Bacillus species. The urease production was 575.87 U/ml and 670.71 U/ml for CT2 and CT5, respectively. Calcite constituted 27.6% and 31% of the total weight of sand samples plugged by CT2 and CT5, respectively. Scanning electron micrography analysis revealed the direct involvement of these isolates in calcite precipitation. This is the first report of the isolation and identification of Bacillus species from cement. Based on the ability of these bacteria to tolerate the extreme environment of cement, they have potential to be used in remediating the cracks and fissures in various building or concrete structures.

A review of microbial precipitation for sustainable construction

“…An increment of 17% in compressive strength of mortars at 28 days was reported [2]) when they used LML to grow S. pasteurii (formerly, B. pasteurii) for biocementation. When CSL media were utilised to grow the bacterial cells for MICP, 35% improvement in the compressive strength of mortars at 28 days was noticed [6,7]. It was higher than the strength achieved with standard nutrient medium.…”

“…Two main benefits of MICP are (i) it can alter pore structure of materials through surface deposition, and (ii) it can strengthen loose granular materials by binding them together. Research so far has established both benefits of MICP; however, it also highlights the [82,59,11,115] Economy Natural or recycled replacement of commercial media with industrial by products [2,6,7] V. Achal, A. Mukherjee / Construction and Building Materials xxx (2015) xxx-xxx geographical and environmental variabilities of the process. To scale the technology up to industrial scale would require standard test protocols and acceptance criteria.…”

“…Achal et al [2,6,7] studied compressive strength of mortars by using industrial by-products such as lactose mother liquor (LML) and corn steep liquor (CSL) as nutrient source. An increment of 17% in compressive strength of mortars at 28 days was reported [2]) when they used LML to grow S. pasteurii (formerly, B. pasteurii) for biocementation.…”

Characterization of bacterial diversity associated with calcareous deposits and drip-waters, and isolation of calcifying bacteria from two Colombian mines

“…Different species and genera have been isolated from secondary deposits (speleothems) in caves, including Bacillus pasteurii, Bacillus subtilis, Myxococcus xanthus, Bacillus amyloliquefaciens, Bacillus cereus, Pseudomonas flurescens, Micrococcus sp., Rhodococus sp., Arthrobacter sp. and many others (Chekroun et al, 2004;Rivadeneyra et al, 2006;Achal et al, 2010;Rusznyák et al, 2012). In addition, it has been suggested that these bacteria have a direct relationship with carbonate deposition and speleothem development (Cacchio et al, 2004;Cacchio et al, 2012;Rusznyák et al, 2012).…”

Improving the strength of sandy soils via ureolytic CaCO<sub>3</sub> solidification by <i>Sporosarcina ureae</i>

“…Given the current data, S. ureae and S. pasteurii are comparable as candidates for ureolytic MICP. This should prompt interest for further investigations differentiating between the two strains on such parameters as protease activity, exopolysaccharide production and biofilm levels, which are also connected to MICP capability (Achal et al, 2010), so as to identify the superior candidate. Some differential work has already been done (Sarmast et al, 2014).…”