Bioengineered yogurt: ‘open source’ medicine

Genetically modified bacteria have a long history of use as gene delivery vectors primarily by intravenous administration, some progressing to clinical trials. Several molecules have been bioengineered into lactobacilli including cyanovirin, interleukin-10, betacarotene, cytosine deaminase and the extracellular domain of TRAIL (tumor necrosis factor related apoptosis inducing ligand). The discovery that a food grade bacterial vector can be ingested and can subsequently translocate out of the gastrointestinal tract to successfully deliver the gene of interest is relatively recent (1). It could have wide ranging implications to be applied to foods containing live bacterial cultures such as yogurt. In particular, the finding suggests that genetically engineered (GM) bacteria in yogurt need only be ingested in sufficient amounts to systemically deliver the product(s) of the engineered genes. Furthermore, the predominantly anaerobic and facultatively anaerobic bacteria in yogurt preferentially colonize hypoxic and necrotic regions such as those found in tumors although other mechanisms are active in such tumor homing as well (2).