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. 1974 Sep;119(3):830–839. doi: 10.1128/jb.119.3.830-839.1974

Characterization of Lactose-Fermenting Revertants from Lactose-Negative Streptococcus lactis C2 Mutants1

B R Cords a,2, L L McKay a
PMCID: PMC245687  PMID: 4368487

Abstract

Partial lactose-fermenting revertants from lactose-negative (lac−) mutants of Streptococcus lactis C2 appeared on a lawn of lac− cells after 3 to 5 days of incubation at 25 C. The revertants grew slowly on lactose with a growth response similar to that for cryptic cells. In contrast to lac+S. lactis C2, the revertants were defective in the accumulation of [14C]thiomethyl-β-d-galactoside, indicating that they were devoid of a transport system. Hydrolysis of o-nitrophenyl-β-d-galactoside-6-phosphate by toluene-treated cells confirmed the presence of phospho-β-d-galactosidase (P-β-gal) in the revertant. However, this enzyme was induced only when the cells were grown in the presence of lactose; galactose was not an inducer. In lac+S. lactis C2, enzyme induction occurred in lactose- or galactose-grown cells. The revertants were defective in EII-lactose and FIII-lactose of the phosphoenolpyruvate-dependent phosphotransferase system. Galactokinase activity was detected in cell extracts of lac+S. lactis C2, but the activity was 9 to 13 times higher in extracts from the revertant and lac−, respectively. This suggested that the lac− and the revertants use the Leloir pathway for galactose metabolism and that galactose-1-phosphate rather than galactose-6-phosphate was being formed. This may explain why lactose, but not galactose, induced P-β-gal in the revertants. Because the revertant was unable to form galactose-6-phosphate, induction could not occur. This compound would be formed on hydrolysis of lactose phosphate. The data also indicate that galactose-6-phosphate may serve not only as an inducer of the lactose genes in S. lactis C2, but also as a repressor of the Leloir pathway for galactose metabolism.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Balbinder E. The Fine Structure of the Loci Tryc and Tryd of Salmonella Typhimurium. II. Studies of Reversion Patterns and the Behavior of Specific Alleles during Recombination. Genetics. 1962 May;47(5):545–559. doi: 10.1093/genetics/47.5.545. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Bissett D. L., Anderson R. L. Lactose and D-galactose metabolism in group N streptococci: presence of enzymes for both the D-galactose 1-phosphate and D-tagatose 6-phosphate pathways. J Bacteriol. 1974 Jan;117(1):318–320. doi: 10.1128/jb.117.1.318-320.1974. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Campbell J. H., Lengyel J. A., Langridge J. Evolution of a second gene for beta-galactosidase in Escherichia coli. Proc Natl Acad Sci U S A. 1973 Jun;70(6):1841–1845. doi: 10.1073/pnas.70.6.1841. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Demko G. M., Blanton S. J., Benoit R. E. Heterofermentative carbohydrate metabolism of lactose-impaired mutants of Streptococcus lactis. J Bacteriol. 1972 Dec;112(3):1335–1345. doi: 10.1128/jb.112.3.1335-1345.1972. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. HERZENBERG L. A. Studies on the induction of beta-galactosidase in a cryptic strain of Escherichia coli. Biochim Biophys Acta. 1959 Feb;31(2):525–538. doi: 10.1016/0006-3002(59)90029-0. [DOI] [PubMed] [Google Scholar]
  6. HIRSCH A. Growth and nisin production of a strain of Streptococcus lactis. J Gen Microbiol. 1951 Feb;5(1):208–221. doi: 10.1099/00221287-5-1-208. [DOI] [PubMed] [Google Scholar]
  7. Hengstenberg W., Penberthy W. K., Hill K. L., Morse M. L. Phosphotransferase system of Staphylococcus aureus: its requirement for the accumulation and metabolism of galactosides. J Bacteriol. 1969 Aug;99(2):383–388. doi: 10.1128/jb.99.2.383-388.1969. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Lee R., Molskness T., Sandine W. E., Elliker P. R. Carbohydrate metabolism in lactic streptococci: fate of galactose supplied in free or disaccharide form. Appl Microbiol. 1973 Dec;26(6):951–958. doi: 10.1128/am.26.6.951-958.1973. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. McKay L. L., Baldwin K. A., Zottola E. A. Loss of lactose metabolism in lactic streptococci. Appl Microbiol. 1972 Jun;23(6):1090–1096. doi: 10.1128/am.23.6.1090-1096.1972. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. McKay L. L., Cords B. R., Baldwin K. A. Transduction of lactose metabolism in Streptococcus lactis C2. J Bacteriol. 1973 Sep;115(3):810–815. doi: 10.1128/jb.115.3.810-815.1973. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. McKay L. L., Walter L. A., Sandine W. E., Elliker P. R. Involvement of phosphoenolpyruvate in lactose utilization by group N streptococci. J Bacteriol. 1969 Aug;99(2):603–610. doi: 10.1128/jb.99.2.603-610.1969. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. McKay L., Miller A., 3rd, Sandine W. E., Elliker P. R. Mechanisms of lactose utilization by lactic acid streptococci: enzymatic and genetic analyses. J Bacteriol. 1970 Jun;102(3):804–809. doi: 10.1128/jb.102.3.804-809.1970. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Molskness T. A., Lee D. R., Sandine W. E., Elliker P. R. -D-phosphogalactoside galactohydrolase of lactic streptococci. Appl Microbiol. 1973 Mar;25(3):373–380. doi: 10.1128/am.25.3.373-380.1973. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Morse M. L., Hill K. L., Egan J. B., Hengstenberg W. Metabolism of lactose by Staphylococcus aureus and its genetic basis. J Bacteriol. 1968 Jun;95(6):2270–2274. doi: 10.1128/jb.95.6.2270-2274.1968. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Reeve E. C., Braithwaite J. A. The lactose system in Klebsiella aerogenes V9A. 2. Galactoside permeases which accumulate lactose or melibiose. Genet Res. 1973 Jun;21(3):273–285. doi: 10.1017/s001667230001346x. [DOI] [PubMed] [Google Scholar]
  16. Simoni R. D., Roseman S. Sugar transport. VII. Lactose transport in Staphylococcus aureus. J Biol Chem. 1973 Feb 10;248(3):966–974. [PubMed] [Google Scholar]
  17. Warren R. A. Lactose-utilizing mutants of lac deletion strains of Escherichia coli. Can J Microbiol. 1972 Sep;18(9):1439–1444. doi: 10.1139/m72-221. [DOI] [PubMed] [Google Scholar]

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