Urease is an enzyme of wide distribution as evidenced by the fact that some 200 species of bacteria, as well as higher plants and animals have been found to possess it (Sumner and Somers, 1953). Pasteur and Miguel were reported to have isolated "urobacilli" from air, soil, and sewage (Cooke and Keith, 1927). Subsequently, the enzyme was found in many soil and intestinal bacteria (Gibson, 1934; ...

During a study of ureolytic microbial calcium carbonate (CaCO(3)) precipitation by bacterial isolates collected from different environmental samples, morphological differences were observed in the large CaCO(3) crystal aggregates precipitated within bacterial colonies grown on agar. Based on these differences, 12 isolates were selected for further study. We hypothesized that the striking differ...

Microbially-induced calcium carbonate (CaCO3) precipitation (MICP) is a widely explored and promising technology for use in various engineering applications. In this review, CaCO3 precipitation induced via urea hydrolysis (ureolysis) is examined for improving construction materials, cementing porous media, hydraulic control, and remediating environmental concerns. The control of MICP is explore...

Urease, a nickel-dependent metalloenzyme, is synthesized by plants, some bacteria, and fungi. It catalyzes the hydrolysis of urea into ammonia and carbon dioxide. Although the amino acid sequences of plant and bacterial ureases are closely related, some biological activities differ significantly. Plant ureases but not bacterial ureases possess insecticidal properties independent of its ureolyti...

Studies of the distribution of ammonia oxidising archaea (AOA) and bacteria (AOB) suggest distinct ecological niches characterised by ammonia concentration and pH, arising through differences in substrate affinity and ammonia tolerance. AOA form five distinct phylogenetic clades, one of which, the 'Nitrososphaera sister cluster', has no cultivated isolate. A representative of this cluster, name...

The genus Nitrospira represents a dominant group of nitrite-oxidizing bacteria in natural and engineered ecosystems. This genus is phylogenetically divided into six lineages, for which vast phylogenetic and functional diversity has been revealed by recent molecular ecophysiological analyses. However, the genetic basis underlying these phenotypic differences remains largely unknown because of th...

Ammonia production from urea by ureolytic oral bacteria is believed to have a significant impact on oral health and the ecological balance of oral microbial populations. In this study we cloned and characterized the urease gene cluster of Actinomyces naeslundii, which is one of the pioneer organisms in the oral cavity and a significant constituent of supragingival and subgingival dental plaque ...

Organic soils are a continuing challenge to civil engineers, as they subject settlements, negatively impacting on engineering infrastructure. To improve the in situ properties of these, chemical soil stabilisers (e.g. cement or lime) can be commonly used. Although successful minimising severe damage, these may have environmental side-effects and lime production is linked 7%–8% overall CO2 emiss...

Abiotic and biotic factors, especially microorganisms, play a role in the development of cave formations existence unique characteristics each cave. Due to ecological conditions that characterize environments, highly specialized microorganisms are main source diverse bioactive compounds, inhabit these environments. The aim this study is determine biotechnological potential bacteria isolated fro...