Funding Information This study was partially supported by the Research Fellowships of the Japan Society for the Promotion of Science for Young Scientists.
Spread and change in stress resistance of Shiga toxin-producing Escherichia coli O157 on fungal colonies
Article first published online: 6 AUG 2013
© 2013 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
How to Cite
Lee, K.-i., Kobayashi, N., Watanabe, M., Sugita-Konishi, Y., Tsubone, H., Kumagai, S. and Hara-Kudo, Y. (2013), Spread and change in stress resistance of Shiga toxin-producing Escherichia coli O157 on fungal colonies. Microbial Biotechnology. doi: 10.1111/1751-7915.12071
Public Interest: Food-borne enterohaemorrhagic, Shiga toxin-producing E. coli 0157 (EHEC, STEC) causes outbreaks of severe diarrhoea which, in some cases progresses to kidney damage [haemolytic uraemic syndrome, (HUS)]. Public awareness of EHEC was raised by recent hamburger-transmitted outbreaks of the disease. This work reveals that fungal contamination of food may increase spread of co-contaminating STEC within the food, because the fungal mycelial network creates migration conduits for the bacteria. The physiological environment of the mycelial conduits also seems to increase bacterial resistance to stresses.
- Article first published online: 6 AUG 2013
- Manuscript Accepted: 24 MAY 2013
- Manuscript Received: 30 MAR 2012
- Research Fellowships of the Japan Society
To elucidate the effect of fungal hyphae on the behaviour of Shiga toxin-producing Escherichia coli (STEC) O157, the spread and change in stress resistance of the bacterium were evaluated after coculture with 11 species of food-related fungi including fermentation starters. Spread distances of STEC O157 varied depending on the co-cultured fungal species, and the motile bacterial strain spread for longer distances than the non-motile strain. The population of STEC O157 increased when co-cultured on colonies of nine fungal species but decreased on colonies of Emericella nidulans and Aspergillus ochraceus. Confocal scanning microscopy visualization of green fluorescent protein-tagged STEC O157 on fungal hyphae revealed that the bacterium colonized in the water film that existed on and between hyphae. To investigate the physiological changes in STEC O157 caused by co-culturing with fungi, the bacterium was harvested after 7 days of co-culturing and tested for acid resistance. After co-culture with eight fungal species, STEC O157 showed greater acid resistance compared to those cultured without fungi. Our results indicate that fungal hyphae can spread the contamination of STEC O157 and can also enhance the stress resistance of the bacteria.