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[The Influence of the Permeability of the Cell Membrane on TMPD Oxydase Activity (author's transl)]
Abstract:
26 bacterial strains representing a variety of both Gram-negative and Gram-postive groups were investigated for their N,N,N',N'-Tetramethyl-1, 4-phenylendiamin (TMPD) oxidase activities and cytochrome contents. The oxidase activites of colonies were examined by dropping the reagent on agar surface colonies. Intact and sonicated cells were tested by recording the oxidation of the TMPD reagent at 546 nm after addition to the cell suspensions. Cytochromes were determined by recording the difference spectra (KBH4-reduced minus H2O2-oxidized) between 400nm and 630 nm. After sonication of intact cells of the "oxidase negative" Enterobacteriaceae except the Proteus strains, the Flavobacterium strains, Streptococcus faecalis, Xanthomonas phaseoli, and the Acinetobacter strains investigated oxidase activities were observed and the oxidase activities of the "oxidase positive" Bacillus and Micrococcus strains and Haemophilus influenzae were increases. These observations show that negative oxidase reactions exhibited by bacterial colonies may not only be due to the lack of the oxidizing enzyme system itself but also to impermeability of the cell membrane for the TMPD reagent. The TMPD oxidase activity could not be correlated to the cytochrome contents of the cells.
Insights
Bacterial N,N,N',N'-Tetramethyl-1,4-phenylendiamin (TMPD) oxidase activity may be underestimated due to cell membrane impermeability, not just enzyme absence. Sonication revealed hidden TMPD oxidase activity in some bacterial strains.
Area of Science:
- Microbiology
- Bacteriology
- Enzymology
Context:
- The N,N,N",N"-Tetramethyl-1,4-phenylendiamin (TMPD) oxidase test is a common method for bacterial identification.
- However, results can be ambiguous, particularly for Gram-negative bacteria.
Purpose:
- To investigate the N,N,N',N'-Tetramethyl-1,4-phenylendiamin (TMPD) oxidase activities and cytochrome contents of various bacterial strains.
- To determine if cell membrane permeability influences TMPD oxidase test results.
Summary:
- Twenty-six bacterial strains (Gram-negative and Gram-positive) were tested for TMPD oxidase activity using intact and sonicated cells.
- Sonication revealed TMPD oxidase activity in previously negative strains (e.g., Enterobacteriaceae, Flavobacterium, Streptococcus faecalis, Xanthomonas phaseoli, Acinetobacter), suggesting cell membrane impermeability as a cause for false-negative results.
- TMPD oxidase activity did not correlate with cytochrome content.
Impact:
- This study highlights the importance of considering cell membrane permeability when interpreting bacterial oxidase test results.
- It suggests that sonication can be a useful adjunct to unmask latent oxidase activity.
- Findings contribute to more accurate bacterial characterization and identification in diagnostic and research settings.