PRESS RELEASE FROM THE ISME JOURNAL (http://www.nature.com/ismej/) This press release is copyrighted to The International Society for Microbial Ecology Journal. Its use is granted only for journalists and news media receiving it directly from the Nature Publishing Group. Salmonella has a sweet tooth for lettuce A possible route by which Salmonella could infect commercially available lettuce is clarified in a report online this week in The ISME Journal. The study reveals that Salmonella actively moves towards a sugar-like carbon source found in the root extracts of lettuce, and that in the presence of these root extracts the bacteria activate genes that enable them to attach to the lettuce root cells. Salmonella bacteria are some of the most commonly known bacterial pathogens to cause human illness, with infection often resulting in food poisoning. Well-established common causes of infection involve poultry, raw eggs and food that has been cooked or defrosted and not eaten straight away. However, it is also recognized that human pathogenic bacteria can be found associated with fresh produce – such as lettuce. In the present study Michel Klerks and colleagues examine the interactions between Salmonella and commercially available lettuce. They report that the Salmonella bacteria actively move towards the lettuce roots, and that this movement is associated with a sugar-like carbon source excreted by the roots. Genetic analysis revealed that pathogenicity-related genes in Salmonella are induced in the presence of the roots – demonstrating that Salmonella is conditioned for attachment to the lettuce roots. The authors suggest that knowledge of the route of infection of susceptible plants could be the basis for development of strategies to prevent infection by the Salmonella bacteria. They stress, however, that the risk of infection of plant produce is still relatively low compared to that of Salmonellosis associated with poultry or eggs. Differential interaction of Salmonella enterica serovars with lettuce cultivars and plantmicrobe factors influencing the colonization efficiency Michel M Klerks, Eelco Franz, Marga van Gent-Pelzer, Carolien Zijlstra and Ariena H C van Bruggen 10.1038/ismej.2007.82 http://www.nature.com/ismej/journal/vaop/ncurrent/abs/ismej200782a.html Author contacts: Michel Klerks (Wageningen University, Plant Research International BV, The Netherlands) Tel: +31 317 476 156; E-mail: Michel.Klerks@WUR.nl Editorial contact: Emma Greenwood (Nature Publishing Group, London) Tel: +44 207 843 4793; E-mail: emma.greenwood@nature.com Media contacts: Helen Jamison (Nature London) Tel: +44 20 7843 4658; E-mail: h.jamison@nature.com Ruth Francis (Nature London) Tel: +44 20 7843 4562; E-mail: r.francis@nature.com