Selectivity in metal uptake by stationary phase microbial populations

In the interaction of metals with the cellular biomass of microorganisms in aqueous solutions, cell wall contituents have been implicated as being responsible for metal binding. Chemical and structural characteristics of cell membranes vary with species and should therefore influence the selective capacity for uptake of different metals by different microorganisms, and thus also influence the behavior of metallic species in the environment. While the rates of uptake of metals by microorganisms have been studied extensively, the comparative capacity for selective uptake of metals by different species of microorganisms under identical experimental conditions has not been studied systematically. To test for this property, cellular biomass derived from eight representative microorganisms has been allowed to interact under similar experimental conditions with acidic solutions of seven heavy metals. The results of these studies show that, in addition to metal selectivity, there is also a species dependent differentiation in the uptake capacity.