Piriyakarnsakul S, Takarada K, Heab KE, Nasu M, Hata M, Furuuchi M. Optimal fluorescent-dye staining time for the real-time detection of microbes: a study of Saccharomyces cerevisiae.
J Appl Microbiol 2020;
128:1694-1702. [PMID:
31925843 DOI:
10.1111/jam.14577]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 12/27/2019] [Accepted: 01/06/2020] [Indexed: 11/28/2022]
Abstract
AIMS
To provide information on the time-dependent behaviour of microbe staining by fluorescent dyes in the order of seconds, which is important in terms of the recent rapid and online techniques for microbe measurements and/or environmental microbe analysis.
METHODS AND RESULTS
For combinations of yeast (Saccharomyces cerevisiae) and typical dyes, including DAPI (4',6-diamidino-2-phenylindole) and Auramine-O, a suspension of yeast cells in ultrapure water was injected into a dye solution in a micro cuvette placed inside a spectrofluorometer and the fluorescence intensity of the resulting solution was measured at 1 s intervals, starting immediately after the mixing and continued until the time for the maximum intensity using various concentrations of yeast and dyes. The relaxation time τ, which corresponds to ~63·2% of the maximum fluorescence intensity, was shown to decrease to below 1 s with increasing DAPI concentration, whereas it remained constant for 2-3 s with increasing Auramine-O concentration, for example at a yeast concentration of 100 µg ml-1 .
CONCLUSIONS
For the conditions of yeast >10 µg ml-1 , DAPI >1 µg ml-1 and Auramine-O >0·1 µg ml-1 , τ could be adjusted to below 5 s to achieve a rapid and stable staining.
SIGNIFICANCE AND IMPACT OF THE STUDY
Design and operating conditions for rapid and online measurements of microbes can be optimized.
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