1887

Abstract

Detailed study of a representative paracolon strain showed that the delayed fermentation of 1% lactose coincided with the development of lactose-fermenting mutants, and that the essential difference between the normal non-lactose-fermenting (lac) organisms and the lactose-fermenting (lac) mutants was one of decreased permeability for lactose. Both types of organism showed the same degree of -galactosidase activity when grown on lactose-free media; the permeability of the lac organisms was increased by raising the concentration of lactose in the medium. On the assumption that permeability is governed by a specific permease which is genetically distinct from -galactosidase, a hypothetical scheme based on these two factors together with the presence or absence of hydrogenlyase suggested the existence of six phenotypes among the paracolon bacilli. In an examination of 51 naturally occurring paracolon strains four of these phenotypes were demonstrated. Since the lactose-fermenting paracolon organisms differ from coliform bacilli merely in being less permeable to 1% lactose, whereas the non-lactose-fermenting organisms differ from both the other groups in lacking -galactosidase activity, it is suggested that the term paracolon should not be applied to this last group but should be restricted to the late-lactose-fermenters. Alternatively, these could be classed within the coliform group.

Loading

Article metrics loading...

/content/journal/micro/10.1099/00221287-23-1-127
1960-08-01
2021-10-16
Loading full text...

Full text loading...

/deliver/fulltext/micro/23/1/mic-23-1-127.html?itemId=/content/journal/micro/10.1099/00221287-23-1-127&mimeType=html&fmt=ahah

References

  1. Cohen G.N., Monod J. 1957; Bacterial permeases. Bact Rev 21:169
    [Google Scholar]
  2. Cohn M., Horibata K. 1959a; Inhibition by glucose of the induced synthesis of the β-galactosidase-enzyme system of Escherichia coli. Analysis of maintenance. J. Bact 78:601
    [Google Scholar]
  3. Cohn M., Horibata K. 1959b; Analysis of the differentiation and of the heterogeneity within a population of Escherichia coli undergoing induced β-galactosidase synthesis. J. Bact 78:613
    [Google Scholar]
  4. Cohn M., Horibata K. 1959c; Physiology of the inhibition by glucose of the induced synthesis of the β-galactosidase-enzyme system of Escherichia cob. J. Bact 78:624
    [Google Scholar]
  5. Cook G.T., Knox R., Tomlinson A.H. 1951; Production of fermentative variants by Shigella sonnei and other ‘late-fermenting’ organisms. Brit. J. exp. Path 32:203
    [Google Scholar]
  6. Deere C.J. 1939; On the ‘activation’ of the lactase of Escherichia coli mutadile . J. Bact 37:473
    [Google Scholar]
  7. Lederberg J. 1950; The β-d-galactosidase of Escherichia coli, strain K-12. J. Bact 60:381
    [Google Scholar]
  8. Lewis I.M. 1934; Bacterial variation with special reference to behaviour of some mutabile strains of colon bacteria in synthetic media. J. Bact 28:619
    [Google Scholar]
  9. Lowe G.H., Evans J.H. 1957; A simple medium for the rapid detection of salmonellalike paracolon organisms. J. clin. Path 10:318
    [Google Scholar]
  10. Rotman B. 1958; Regulation of enzymatic activity in the intact cell. The β-d-galactosidase of Escherichia coli . J. Bact 76:1
    [Google Scholar]
http://instance.metastore.ingenta.com/content/journal/micro/10.1099/00221287-23-1-127
Loading
/content/journal/micro/10.1099/00221287-23-1-127
Loading

Data & Media loading...

Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error