Phosphatase overproduction and enhanced uranium accumulation by a stable mutant of aCitrobactersp. isolated by a novel method

A phosphatase-overproducing mutant of a Citrobacter sp. was isolated by a novel method. This exploited the proposed role for the enzyme in metal detoxification by precipitation of heavy metals with enzymically-liberated inorganic phosphate at the cell surface. The mutant, tolerant to an otherwise growth-inhibitory concentration of copper, overproduced phosphatase approx. 3-fold as compared to the parent strain. With a comparable enhancement in uranium uptake, the industrial potential of the mutant in metal waste detoxification is apparent, and is discussed.