Gut Escherichia coli expressing Pb2+-adsorption protein reduces lead accumulation in grass carp, Ctenopharyngodon idellus.

ABSTRACT Lead (Pb2+) is easy to accumulate in fish which become a major source of Pb2+ exposure to humans. In this study, a recombinant Escherichia coli strain expressing Pb2+-specific surface-binding protein anchored by the ice nucleation protein was introduced into grass carp (Ctenopharyngodon idellus) gut to investigate its protective effect against dietary Pb2+ exposure. Pb2+ mostly precipitated on the surface of the engineered strain through Pb2+-specific surface-binding protein, with a maximum adsorption efficiency of 73% and an adsorption capacity of 163 μmol/g dry cells. The Pb2+ concentration in engineered bacteria-fed grass carp was reduced significantly, and the residual level of Pb2+ in feces was increased by 76%, compared with the control group. Meantime, the engineered bacteria were able to mitigate the oxidative stress and histological alterations of intestines and dysbiosis of gut microbiota induced by Pb2+exposure. Thus, the engineered bacterium that can effectively reduce Pb2+ residue in grass carp might be a useful tool for decontamintion of lead in aquatic organisms.