Non-pathogenic Listeria strains acquiring pathogenic genes (IMAGE) University of Johannesburg Caption Dr Thendo Mafuna from the Department of Biochemistry at the University of Johannesburg (UJ). In this composite photo, Dr Mafuna is in one of the UJ Biochemistry laboratories, and facing genetic data for Listeria innocua. Food-borne bacteria Listeria innocua and L. welshimeri are often regarded as harmless, compared to the deadly Listeria monocytogenes. But both these species are developing an unexpected number of harmful characteristics that can make food safety measures more difficult to maintain. Credit Photo of data and Dr Mafuna by Therese van Wyk, University of Johannesburg. Usage Restrictions No restrictions. License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.