原文：They start out as industrial yeast or nonpathogenic strains o

原文：They start out as industrial yeast or nonpathogenic strains of E. coli, but LS9 modifies them by custom-designing their DNA.
译文：它们起初只是工业酵母或大肠杆菌的原菌株，但LS9通过定制设计它们的DNA对其进行改造。
【正确答案】：
改译：它们起初只是工业酵母或大肠杆菌的非病原菌株，但LS9通过定制设计它们的DNA对其进行改造。