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Glucose fuels Salmonella's fire

By Joe Whitworth+

13-May-2014

Glucose is a major nutrient used by Salmonella Typhimurium during infection in humans, according to research.

Salmonella converts glucose to pyruvate in a process called glycolysis, which also releases energy needed to fuel growth and reproduction.

A source of energy and nutrition is vital, and knowing what Salmonella uses could inform new strategies to prevent infection, said the study.

The Institute of Food Research (IFR) and the Biotechnology and Biological Sciences Research Council, looked at how S. Typhimurium bacteria transmits through the food chain and why they are so effective.

Constructed strain

Dr Arthur Thompson and his team constructed S. Typhimurium strains lacking certain key genes in important metabolic pathways and examined how well these mutated strains reproduced in human epithelial cells, grown in cultures.

Knocking out one enzyme in the process and enzymes used to transport glucose into the bacteria reduced S. Typhimurium’s ability to reproduce in epithelial cells, but didn’t eradicate it completely.

Dr Arthur Thompson told FoodQualityNews.com the pathogen uses glucose to grow and divide in host cells.

“Once we know what it uses and know which genes are required for it to metabolise we can make strains which have them genes missing and use them as potential live attenuated vaccine strains.

“We knew Salmonella used nutrients but we didn’t know exactly what it feeds off when living in the host cells.

“Now we know it uses glucose but we want to know what the other nutrients are, this will enable us to gain more leverage and find therapeutic strains.” 

Salmonella’s movements

The first stage of infection is to get into the cells that line the gut, these epithelial cells are adapted to defend against such attacks, but Salmonella has can overcome these and be more virulent.

It also needs these virulence genes to overcome the cells of the immune system, which it invades to move around the body.

The researchers said that it was unknown how Salmonella fuelled itself to do this but the findings show glucose is one of the nutrients used.

However, it is also able to use other nutrients, which is the next stage in the research.

The findings contrasts with previous findings from similar experiments on macrophage cells, as for successful macrophage invasion, glycolysis is essential.

Macrophages are the immune cells sent to destroy Salmonella but the pathogen invades the macrophages.

Infected macrophages carry Salmonella around the body causing a potentially fatal systemic infection.

Source: PLOS ONE

Online ahead of print, DOI: 10.1371/journal.pone.0096266

Nutritional and metabolic requirements for the infection of HeLa cells by Salmonella enterica serovar Typhimurium

Authors: Steven D. Bowden, Amanda C. Hopper-Chidlaw, Christopher J. Rice, Vinoy K. Ramachandran, David J. Kelly and Arthur Thompson