When raw tomatoes turn health risk

Washing does not remove Salmonella typhimurium bacteria from them, a study by IISc team finds

Washing tomatoes thoroughly will not get rid of Salmonella typhimuriumbacteria, which cause gastroenteritis. Researchers at the Indian Institute of Science (IISc) Bengaluru have found that infection with S. typhimurium is a pre-harvest phenomenon and not a post-harvest problem as commonly thought. The researchers found irrefutable evidence of the bacteria entering the plants through tiny openings that form on the main root for the lateral roots to emerge. Contaminated irrigation water and open defecation are the main sources of this bacterial strain in the soil.

While the bacteria are killed on cooking, Salmonella infection is usually caused when raw vegetables used in salad contain the bacteria. “While studies are now being done to see if the bacteria infect other vegetables used in salad in the same manner, the key is to avoid eating any raw vegetable in the current scenario,” said Dipshikha Chakravortty, from the IISc’s Department of Microbiology and Cell Biology, who led the team.

Salmonella bacteria do not have the necessary enzymes to degrade plant cellulose and pectin and so cannot degrade cell wall. So active invasion by degrading the cell wall is not possible. Hence, S. typhimurium have to rely on natural entry points. “Lateral roots are formed by remodelling of the main root. During the formation of the lateral root, a small opening is formed for the lateral root to emerge,” said Professor Chakravortty. The pathogen takes advantage of these openings in the primary root to enter the plant.....Read more


Source web page: The Hindu

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