We have located links that may give you full text access.
Common dyes used to determine bacterial polysaccharides on agar are affected by medium acidification.
Canadian Journal of Microbiology 2017 June
In this work, we highlight effects of pH on bacterial phenotypes when using the bacteriological dyes Aniline blue, Congo red, and Calcofluor white to analyze polysaccharide production. A study of galactose catabolism in Sinorhizobium meliloti led to the isolation of a mutation in dgoK1, which was observed to overproduce exopolysaccharides when grown in the presence of galactose. When this mutant strain was spotted onto plates containing Aniline blue, Congo red, or Calcofluor white, the intensity of the associated staining was strikingly different from that of the wild type. Additionally, a Calcofluor dull phenotype was observed, suggesting production of a polysaccharide other than succinoglycan. Further investigation of this phenotype revealed that these results were dependent on medium acidification, as buffering at pH 6 had no effect on these phenotypes, while medium buffered at pH 6.5 resulted in a reversal of the phenotypes. Screening for mutants of the dgoK1 strain that were negative for the Aniline blue phenotype yielded a strain carrying a mutation in tkt2, which is annotated as a putative transketolase. Consistent with the plate phenotypes, when this mutant was grown in broth cultures, it did not acidify its growth medium. Overall, this work shows that caution should be exercised in evaluating polysaccharide phenotypes based strictly on the use of dyes.
Full text links
Related Resources
Get seemless 1-tap access through your institution/university
For the best experience, use the Read mobile app
All material on this website is protected by copyright, Copyright © 1994-2024 by WebMD LLC.
This website also contains material copyrighted by 3rd parties.
By using this service, you agree to our terms of use and privacy policy.
Your Privacy Choices
You can now claim free CME credits for this literature searchClaim now
Get seemless 1-tap access through your institution/university
For the best experience, use the Read mobile app