Junillon Thomas, Morand Lucie, Flandrois Jean Pierre
Université Lyon 1, CNRS, UMR5558, Laboratoire de Biométrie et Biologie Evolutive, F-69622 Villeurbanne, France; CNRS, UMR5558, Laboratoire de Biométrie et Biologie Evolutive, F-69622 Villeurbanne, France; bioMerieux SA département Microbiologie industrielle, Chemin de l'Orme, 69280 Marcy l'Etoile, France.
bioMerieux SA département Microbiologie industrielle, Chemin de l'Orme, 69280 Marcy l'Etoile, France.
Food Microbiol. 2014 Sep;42:132-5. doi: 10.1016/j.fm.2014.03.008. Epub 2014 Mar 19.
Tetrazolium salts (TTZ), such as tetrazolium violet (TV), have been widely used for microbiological studies. The formation of the colored formazan product due to bacterial reduction of the uncolored reagent is extensively exploited to stain cells or colonies in agar or on filters. But an important toxic effect of tetrazolium salts on bacteria exists that limits their use at high concentrations, impairing the efficient staining of the colonies. This is especially the case for Salmonella spp. where we observed, using a classic photometric approach and mathematical modeling of the growth, an important impact of tetrazolium violet on the apparent growth rate below the inhibitory concentration. In this study, we demonstrate that adding magnesium to the medium in the presence of TV leads to a significant increase in the apparent growth rate. Moreover, when higher TV concentrations are used which lead to total inhibition of Salmonella strains, magnesium addition to the culture media allows growth and TV reduction. This effect of magnesium may allow the use of higher TTZ concentrations in liquid growth media and enhance bacteria detection capabilities.
四唑盐（TTZ），如四唑紫（TV），已广泛用于微生物学研究。由于细菌将无色试剂还原而形成的有色甲臜产物被广泛用于对琼脂或滤膜上的细胞或菌落进行染色。但是四唑盐对细菌存在一种重要的毒性作用，这限制了它们在高浓度下的使用，从而影响菌落的有效染色。对于沙门氏菌属尤其如此，在那里我们使用经典的光度法和生长的数学模型观察到，低于抑制浓度时，四唑紫对表观生长速率有重要影响。在本研究中，我们证明在有TV存在的情况下向培养基中添加镁会导致表观生长速率显著增加。此外，当使用更高浓度的TV导致沙门氏菌菌株完全抑制时，向培养基中添加镁可使细菌生长并还原TV。镁的这种作用可能允许在液体生长培养基中使用更高浓度的TTZ，并提高细菌检测能力。
