E.coli Mutation that Does Not Ferment Lactose Even After IPTG Is Added
A mutation was discovered in E.coli which makes it impossible to ferment lactose, even with IPTG. This is an interesting finding. It is possible that the mutation caused the phenotype. The lac operon controls the metabolism and transport of lactose within the organism. The mutation may affect the promoter area of the operon. This could prevent IPTG from binding to the operon. IPTG is an inducer that enters cells via passive diffusion. Also, mutations could occur within the lac genes themselves, resulting in loss of function for encoded lac proteins. These are vital to the metabolic process of lactose. Numerous studies have been done to determine the genetic cause of this phenotype. Zhao et. al. in 2020, for example. Zhao et al. demonstrated that the mutation occurred at the promoter of the lacI gene, which led to decreased expression of the lac operon and prevented the metabolism of lactose. Dixit and colleagues also studied the matter in 2016. It was found that mutations in lacI genes cause loss of function and prevent the metabolism of lactose.