Abstract
Urease is an enzyme produced by ureolytic microorganisms which hydrolyzes urea into ammonia and carbon dioxide. Microbial urease has wide applications in biotechnology, agriculture, medicine, construction, and geotechnical engineering. Urease-producing microbes can be isolated from different ecosystems such as soil, oceans, and various geological formations. The aim of this study was to isolate and characterize rapid urease-producing bacteria from Ethiopian soils. Using qualitative urease activity assay, twenty urease-producing bacterial isolates were screened and selected. Among these, three expressed urease at high rates as determined by a conductivity assay. The isolates were further characterized with respect to their biochemical, morphological, molecular, and exoenzyme profile characteristics. The active urease-producing bacterial isolates were found to be nonhalophilic to slightly halophilic neutrophiles and aerobic mesophiles with a range of tolerance towards pH (4.0–10.0), NaCl (0.25—5%), and temperature (20–40°C). According to the API ZYM assays, all three isolates were positive for alkaline phosphatase, leucine aryl amidase, acid phosphatase, and naphthol_AS_BI_phosphohydrolase. The closest described relatives of the selected three isolates (Isolate_3, Isolate_7, and Isolate_11) were Bacillus paramycoides, Citrobacter sedlakii, and Enterobacter bugandensis with 16S rRNA gene sequence identity of 99.0, 99.2, and 98.9%, respectively. From the study, it was concluded that the three strains appear to have a relatively higher potential for urease production and be able to grow under a wider range of growth conditions.
Highlights
Urease is an enzyme that catalyzes the hydrolysis of urea by all plants and many algae, fungi, and bacteria [1]
Microbial urease has been studied in clinical samples as it is related to the virulence of pathogenic microorganisms [4], contributing to urinary stones, pyelonephritis, and gastric ulceration [5, 6]
In the last two decades, the use of microbial urease has switched from clinical relevance to geotechnical engineering and applied biotechnology [9], because of the abilities of microorganisms to induce calcite precipitation, a common natural soil cementing agent, in the presence of urea and calcium ions [10, 11]
Summary
Eshetu Mekonnen ,1 Ameha Kebede, Asefa Nigussie, Gessese Kebede, and Mesfin Tafesse. E aim of this study was to isolate and characterize rapid urease-producing bacteria from Ethiopian soils. Using qualitative urease activity assay, twenty urease-producing bacterial isolates were screened and selected. E isolates were further characterized with respect to their biochemical, morphological, molecular, and exoenzyme profile characteristics. E active urease-producing bacterial isolates were found to be nonhalophilic to slightly halophilic neutrophiles and aerobic mesophiles with a range of tolerance towards pH (4.0–10.0), NaCl (0.25—5%), and temperature (20–40°C). E closest described relatives of the selected three isolates (Isolate_3, Isolate_7, and Isolate_11) were Bacillus paramycoides, Citrobacter sedlakii, and Enterobacter bugandensis with 16S rRNA gene sequence identity of 99.0, 99.2, and 98.9%, respectively. It was concluded that the three strains appear to have a relatively higher potential for urease production and be able to grow under a wider range of growth conditions
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