Can GM “improve” probiotic bacteria without turn them into dangerous pathogens?
Probiotic bacteria modulate the immune system and provide an ecological balance in the gut that excludes disease-causing microbes. Germ-free mice bred in the laboratory have less immune cells, and tend to leak more food antigen across the intestinal barrier. These conditions improve after about a month of exposure to bacteria. Probiotic bacteria must not be pathogenic, however; and it is essential for probiotic treatments to be tested for safety. The vast majority of applications have been free of pathological outcomes; but there has been one case of local infection from a rogue Lactobacillus strain. The prospect that genetic modification might “improve” probiotic microbes must be seriously balanced against the potential of turning harmless, beneficial microbes into dangerous pathogens (“No biosecurity without biosafety”, ISIS report 16 March 2005), particularly in the case of bacteria that naturally inhabit the human gut. The complete genome sequence of the probiotic Lactobacillus aci
