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Ammonia colourimetric indicator for measuring urease and ureolytic bacteria concentrations.

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Τίτλος: Ammonia colourimetric indicator for measuring urease and ureolytic bacteria concentrations.
Συγγραφείς: Watson M; School of Chemistry and Chemical Engineering, Queens University Belfast, Stranmillis Road, Belfast, BT9 5AG, UK., O'Rourke C; School of Chemistry and Chemical Engineering, Queens University Belfast, Stranmillis Road, Belfast, BT9 5AG, UK., Mills A; School of Chemistry and Chemical Engineering, Queens University Belfast, Stranmillis Road, Belfast, BT9 5AG, UK. Electronic address: andrew.mills@qub.ac.uk.
Πηγή: Biosensors & bioelectronics [Biosens Bioelectron] 2026 Feb 15; Vol. 294, pp. 118238. Date of Electronic Publication: 2025 Nov 19.
Τύπος έκδοσης: Journal Article
Γλώσσα: English
Στοιχεία περιοδικού: Publisher: Elsevier Advanced Technology Country of Publication: England NLM ID: 9001289 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1873-4235 (Electronic) Linking ISSN: 09565663 NLM ISO Abbreviation: Biosens Bioelectron Subsets: MEDLINE
Imprint Name(s): Publication: Oxford : Elsevier Advanced Technology
Original Publication: [Barking, Essex, England] : Elsevier Applied Science, 1989-
Ιατρικοί όροι (MeSH): Urease*/analysis , Urease*/isolation & purification , Urease*/metabolism , Colorimetry*/methods , Ammonia*/analysis , Ammonia*/metabolism , Biosensing Techniques*/methods , Urea*/metabolism , Bacteria*/isolation & purification , Bacteria*/enzymology
Περίληψη: An effectively irreversible colourimetric ammonia (NH3) indicator is used to develop two new methods for determining the concentrations of, (i) urease [urease], and (ii) ureolytic bacteria under aerobic and anaerobic conditions. In both methods digital colour analysis (DCA) of a photographic image of the indicator is used to provide a value for the apparent absorbance, A', which reflects the level of NH3 present. In (i) the indicator is placed in a solution containing urea and the urease sample under test, and photographed as a function of incubation time, t. DCA of the photographs yields an A' vs t plot, from which a value for the time taken for the indicator to reach its half-way colour changing point, t50, is determined, the reciprocal of which is directly proportional to [urease]. In (ii), the indicator is placed in a Falcon™ tube containing a urea-based growth medium inoculated with a ureolytic bacterium of known concentration (units: CFU/mL), and photographed as a function of t. The resulting 'S' shaped A' vs t profile is used to determine a value of the half-way colour change, the threshold time, TT, which is shown to be directly proportional to log(CFU/mL) over the range 101-108 CFU/mL for ureolytic bacteria such as P. stuartii and P. mirabilis, even in the presence of a non-ureolytic bacterial species, such as E. coli. The latter novel NH3 indicator based micro-respirometry method for measuring TVC (NH3 μR-TVC) works under anaerobic and aerobic conditions.
(Copyright © 2025 The Authors. Published by Elsevier B.V. All rights reserved.)
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Contributed Indexing: Keywords: Ammonia; Bacteria; Indicator; Microrespirometry; TVC; Urease
Substance Nomenclature: EC 3.5.1.5 (Urease)
7664-41-7 (Ammonia)
8W8T17847W (Urea)
Entry Date(s): Date Created: 20251121 Date Completed: 20251206 Latest Revision: 20251206
Update Code: 20260130
DOI: 10.1016/j.bios.2025.118238
PMID: 41270361
Βάση Δεδομένων: MEDLINE
Περιγραφή
ISSN:1873-4235
DOI:10.1016/j.bios.2025.118238