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. 2021 Jul 9:2021:8888641.
doi: 10.1155/2021/8888641. eCollection 2021.

Isolation and Characterization of Urease-Producing Soil Bacteria

Eshetu Mekonnen  1 , Ameha Kebede  2 , Asefa Nigussie  3 , Gessese Kebede  3 , Mesfin Tafesse  3
Affiliations

Isolation and Characterization of Urease-Producing Soil Bacteria

Eshetu Mekonnen et al. Int J Microbiol. .

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.

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Conflict of interest statement

The authors declare that there are no conflicts of interest regarding this paper.

Figures

Figure 1
Figure 1
Specific urease activity.
Figure 2
Figure 2
Molecular phylogenetic analysis by maximum likelihood method based on almost-full-length 16S rRNA gene sequences illustrating the phylogenetic position of Isolate_3, Isolate_7, and Isolate_11 and related taxa. The percentage of trees in which the associated taxa clustered together are shown next to the branches.
Figure 3
Figure 3
(a, b, c) Phase-contrast photomicrographs of strains: Isolate_3, Isolate_7, and Isolate_11.
Figure 4
Figure 4
pH growth optimum and range analysis of the strains Isolate_11, Isolate_7, and Isolate_3, respectively.
Figure 5
Figure 5
Temperature optimum and range analysis of strains of Isolates_11, Isolate_7, and Isolate_3, respectively.
Figure 6
Figure 6
NaCl tolerance, optimum, and range analysis of the strains of Isolate_7, Isolate_11, and Isolate_3, respectively.
See this image and copyright information in PMC

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