Lactobacillus GG (LGG) is a bacterium that naturally lives in the human gastrointestinal tract. LGG was named after its co-discoverers, Gorbach and Goldin. The scientific name for LGG is Lactobacillus rhamnosus.LGG is a probiotic.actobacillus GG (LGG) is a bacterium that naturally lives in the human gastrointestinal tract. LGG was named after its co-discoverers, Gorbach and Goldin. The scientific name for LGG is Lactobacillus rhamnosus.