A method for the quantification of bacterial protein in the presence of Jarosite

A variation on Peterson's modification of the Lowry method for microbial protein determination was developed in which 10% (w/v) oxalic acid was used to remove jarosite. This allowed the quantification of Thiobacillus ferrooxidans entrapped in solid jarosite or in aqueous suspensions containing jarosite. The quantity of protein measured was not affected by the amount of jarosite in the culture, the concentration of oxalic acid, or the time of exposure (up to 72 h) of the sample to oxalic acid. An application of this method was demonstrated in the quantification of biomass immobilized in jarosite on the surface of polystyrene beads in an inverse fluidized bed bioreactor used for the rapid microbial oxidation of ferrous iron.