[Trials to improve the media used for the methyl red reaction (MRT). II].
The evolution of the methyl rot reaction (MRT), expressed by the pH dynamics in the first 18 hours was examined. A medium made of caseine or soya hydrolysate distributed in small volumes, was experimented versus a control broth made of meat peptone (Clark-Lubs). For Klebsiella the results showed that in the control group the pH acidifies and remains low, thus mimicking a positive reaction. In the caseine/soya medium, a decrease of pH at 4-8 hours is first noticed. Initial acidification, consecutive to glucose fermentation, is then counteracted by another type of processes that change the reaction direction. pH increases at 12-18 hours towards neutrality hat can be easily exceeded in 24 hours. Alkaline reversion is favoured by: a--the richer content in aa diaminomonocarboxylic and b--assurance of a large aeration by increase of the ratio between surface and volume. For evidencing realkalinization, characteristic of Klebsiellae, the medium with caseine/soya, including "ab initio" either Bromkresolpurpur (pH = 5.2-6.2) or Bromtimolblau (pH = 6.7-7.6) is experimented. The medium ensures the direct reading of the reaction, at 18-24 hours, by the colour change. The results correspond to metric pH recording. When the results are not clear (slowly metabolic strains), the culture may be reincubated, an important advantage versus the Clark-Lubs procedure.
Marica
D
D
Facultatea de Medicină Veterinară, Departamentul Microbiologie, Cluj-Napoca.
Rudăreanu
N
N
Kadar
I
I
Todoran
L
L
Rusu
A
A
D001391:Azo Compounds; D001431:Bacteriological Techniques; D004396:Coloring Agents; D003470:Culture Media; D004755:Enterobacteriaceae / Q000302:isolation & purification*; D004756:Enterobacteriaceae Infections / Q000175:diagnosis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D013997:Time Factors
D001391:Azo Compounds; D004396:Coloring Agents; D003470:Culture Media; C008492:methyl red
Incercări de optimizare a mediilor folosite pentru reacţia roşului de methyl (MRT). Nota II.