The influence of organic and inorganic nitrogen sources on low temperature growth of Shiga-like verotoxin-producing Escherichia coli (VTEC) was studied. Seven verotoxigenic strains were studied in complex and minimal medium systems. Results indicate that verotoxigenic strains require an organic nitrogen source (amino acids or peptides) for growth at 6.5°C. Minimal medium systems containing ammonium sulfate as the nitrogen source and glucose as the carbon source did not support the growth of any strain at 6.5°C. However, glucose and fructose minimal media systems with ammonia sulfate as the source of nitrogen supported growth at 9.5°C. Amino acids and/or peptides could serve as the source of nitrogen, carbon and energy for growth of some VTEC at 6.5°C. These results suggest that VTEC can readily grow at 6.5°C owing to the availability of organic nitrogen sources and sugars in foods.
Bibliographical noteFunding Information:
This article is published as paper No. 971180029 of the contribution series of the Minnesota Agricultural Experiment Station based on research conducted under project No. 1854 and supported by funds from the Minnesota South Dakota Dairy Foods Research Center.