Development of method to quantify extracellular carbohydrate complexes produced by Escherichia coli O157:H7

J. H. Ryu, L. R. Beuchat

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

Aims: The aim of this study was to optimize conditions to separate extracellular carbohydrate complexes (ECC) produced by Escherichia coli O157:H7 and to standardize the amount of ECC produced on a per cell basis. Methods and Results: ECC fraction I was removed from E. coli O157:H7 cells produced on tryptic soya agar and lettuce juice agar by centrifugation. To remove ECC fraction II, cells were heated at 100°C for 10 min, then centrifuged. The sum of ECC fractions I and II was considered as the total ECC produced by E. coli O157:H7. A correlation between cell mass and turbidity (O.D. 750nm) of cell suspensions was determined. Cell mass has a linear relationship (R2 = 0.93) with turbidity of cell suspensions from which ECC is removed. The amount of ECC produced on a per cell basis was calculated by dividing total amount of ECC (μg ml-1) produced by the turbidity (O.D.750nm) of heated cell suspension after removal ECC fractions I and II. Conclusions: A method for separating ECC from cells of E. coli O157:H7 has been developed and conditions have been optimized. A standard method to estimate the amount of ECC produced on a per cell basis was also developed. Significance and Impact of the Study: Using these procedures to prepare extract of ECC from E. coli O157:H7 and to standardize values, production of ECC on a per cell basis can be estimated and a comparison of the amount of ECC produced by the pathogen grown under different environmental conditions can be accurately measured.

Original languageEnglish
Pages (from-to)1304-1314
Number of pages11
JournalJournal of Applied Microbiology
Volume95
Issue number6
DOIs
Publication statusPublished - 2003
Externally publishedYes

Keywords

  • EPS
  • Escherichia coli O157:H7
  • Exopolysaccharides
  • Extracellular carbohydrate complexes

ASJC Scopus subject areas

  • Biotechnology
  • Applied Microbiology and Biotechnology

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