Adsorption of lead using mixed cultures of Bacillus subtilis and Pseudomonas aeruginosa.

Abstract

Adsorption using bacterial cultures is one of the methods broadly studied and used in the removal of heavy metal contaminants in water. Pseudomonas aeruginosa and Bacillus subtilis are two of the known bacteria that can bioadsorb lead. This study determined the adsorptive ability of these species by measuring the amount of their lead uptake. Results show that P. aeruginosa exhibited higher percent adsorption, of 35.57%, than B. subtilis,with 27.84%. There is an apparent decrease in amount of lead uptake when these cultures were mixed, showed by the 17.53% percent adsorption exhibited by the mixed cultures. Statistical tests revealed two significant groups, with the first comprising of B. subtilis and P. aeruginosa and the other of B. subtilis and mixed culture. The adsorption process was found to fit the Freundlich model, implying that there is a possible interaction between P. aeruginosa and B. subtilis in the mixed culture which resulted to a decrease in their adsorptive abilities. This study concludes that the mixtures of heat-killed P. aeruginosa and B. subtilis have lower lead adsorptive ability than the individual cultures.