Hostname: page-component-78c5997874-v9fdk Total loading time: 0 Render date: 2024-11-20T01:10:53.849Z Has data issue: false hasContentIssue false
  • English
  • Français

The threshold growth response of Lactobacillus casei to 5-methyl-tetrahydrofolic acid: implications for folate assays

Published online by Cambridge University Press:  24 July 2007

A. J. A. Wright  and
D. R. Phillips
A. J. A. Wright
Affiliation:
AFRC Food Research Institute, Colney Lane, Norwich NR4 7, UA
D. R. Phillips
Affiliation:
AFRC Food Research Institute, Colney Lane, Norwich NR4 7, UA
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

1. The comparative and absolute growth response of Lactobacillus casei was measured nephelometrically for time periods of 17–23 h in the microbiological assay of folic acid and 5-methyl-tetrahydrofolic acid at concentrations of 0–8 ng/10 ml basal medium at pH 6.8.

2. At concentrations of 0–1 ng/10 ml the comparative growth response to 5-methyl-tetrahydrofolic acid was markedly depressed whereas growth was the same at 2 ng/10 ml and above. Comparative growth was unaffected by the length of assay incubation, depressed growth being due to differences in log-phase growth rates with the rate-plot for 5-methyl-tetrahydrofolic acid being sigmoidal and for folk acid being a rectangular hyperbola with linearity only in the 0–1 ng/10 ml range. The reciprocal rate-plot for folic acid was linear whereas that for 5-methyl-tetrahydrofolic acid was coincidental only in part, giving rise to the same estimate of maximum velocity and substrate concentration for half-maximum velocity, with the exhibition of a strong threshold at low concentration.

3. A previous observation (Phillips & Wright, 1982) that the L. casei growth response to 5-methyl-tetrahydrofolic acid may be significantly less than that to folic acid is confirmed as is the long-established view that the response to both folates may be equal. In the light of current knowledge regarding folate-binding, transport and metabolism by L. casei, it is argued that the intracellular oxidation of 5-methyl-tetrahydrofolic acid to 5, 10-methylene-tetrahydrofolic acid is a rate-limiting step at low substrate concentrations, subsequently giving rise to a threshold growth response peculiar to 5-methyl-tetrahydrofolic acid. Since the rate of L. cusei growth with folk acid is not linearabove 1 ng/10 ml, it is recommended that microbiological folate assays be conducted only in the 0–1 ng/10 ml range and at a pH that elicits the same growth response from L. casei to 5-methyl-tetrahydrofolic acid as to folic acid and other folate monoglutamates.

Type
Papers on General Nutrition
Information
British Journal of Nutrition , Volume 53 , Issue 3 , May 1985 , pp. 569 - 573
Copyright
Copyright © The Nutrition Society 1985

References

REFERENCES

Bakerman, H. A. (1961). Analytical Biochemistry 2, 558–567.CrossRefGoogle Scholar
Bates, C. J., Black, A. E., Phillips, D. R., Wright, A. J. A. & Southgated, D. A. T. (1982). Human Nutrition: Applied Nutrition 36A, 422–429.Google Scholar
Bell, J. G. (1974). Laboratory Practice 23, 235–242, 252.Google Scholar
Bird, O. D. & McGlohon, V. M. (1972). In Analytical Microbiology, vol. 2, pp. 409–437 [Kavanagh, F., editor]. New York: Academic Press.CrossRefGoogle Scholar
Bognar, A. L. & Shane, B. (1983). Journal of Biological Chemistry 258, 12574–12581.CrossRefGoogle Scholar
Cooper, B. A. (1970). Biochimica et Biophysica Acta 208, 99–109.CrossRefGoogle Scholar
Futterman, S. & Silverman, M. (1957). Journal of Biological Chemistry 224, 31–40.CrossRefGoogle Scholar
Henderson, G. B. & Huennekens, F. M. (1974). Archives of Biochemistry & Biophysics 164, 722–728.CrossRefGoogle Scholar
Henderson, G. B. & Huennekens, F. M. (1977). Journal of Biological Chemistry 252, 3760–3765.CrossRefGoogle Scholar
Herbert, V. (1966). Journal of Clinical Pathology 19, 12–16.CrossRefGoogle Scholar
Laurence, K. M., James, N., Miller, M. H. & Campbell, H. (1980). British Medical Journal 281, 1592–1594.CrossRefGoogle Scholar
Laurence, K. M., James, N., Miller, M. H., Tennant, G. B. & Campbell, H. (1981). British Medical Journal 282, 1509–1511.CrossRefGoogle Scholar
Paul, A. A. & Southgate, D. A. T. (1978). McCance and Widdowson's The Composition of Foods. London: H.M. Stationery Office.Google Scholar
Phillips, D. R. & Wright, A. J. A. (1982). British Journal of Nutrition 47, 183–189.CrossRefGoogle Scholar
Phillips, D. R. & Wright, A. J. A. (1983). British Journal of Nutrition 49, 181–186.CrossRefGoogle Scholar
Scott, J. M. & Weir, D. G. (1976). Clinics in Haematology, vol. 5, pp. 547–568, London: W. B. Saunders Co. Ltd.Google Scholar
Shane, B., Bognar, A. L., Goldfarb, R. D. & Le Bowitz, J. H. (1983). Journal of Bacteriology 153, 316–325.CrossRefGoogle Scholar
Shane, B. & Stokstad, E. L. R. (1975). Journal of Biological Chemistry 250, 2243–2253.CrossRefGoogle Scholar
Shane, B. & Stokstad, E. L. R. (1976). Journal of Biological Chemistry 251, 3405–3410.CrossRefGoogle Scholar
Shane, B. & Stokstad, E. L. R. (1977 a). Journal of General Microbiology 103, 249–259.CrossRefGoogle Scholar
Shane, B. & Stokstad, E. L. R. (1977 b). Journal of General Microbiology 103, 261–270.CrossRefGoogle Scholar
Shane, B., Tamura, T. & Stokstad, E. L. R. (1980). Clinica Chimica Acta 100, 13–19.CrossRefGoogle Scholar
Smithells, R. W., Sheppard, S. & Schorah, C. J. (1980). Lancet i, 339–340.CrossRefGoogle Scholar
Smithells, R. W., Sheppard, S. & Schorah, C. J. (1981). Archives of Disease in Childhood 56, 911–918.CrossRefGoogle Scholar
Stokstad, E. L. R. & Oace, S. M. (1965). In Newer Methods of Nutritional Biochemistry, vol. 2, pp. 285–313 [Albanese, A. A., editor]. New York: Academic Press.Google Scholar
Stokstad, E. L. R. & Thenen, S. W. (1972). In Analytical Microbiology, vol. 2, pp. 387–408 [Kavanagh, F, editor]. New York: Academic Press.CrossRefGoogle Scholar