Enzyme-based glucose delivery: a possible tool for biosorbent preparation for heavy metal removal from polluted environments

This study was performed to examine the influence of the controlled glucose supply technology, EnBase(A (R)) Flo, on growth and heavy metals uptake capacity of two Bacillus strains isolated from food industry wastewater. Bacillus sp. growth on EnBase Flo (mineral salt complex medium containing starch-derived polymer as substrate) was examined in 24 deep well plates, controlling the glucose amount release by adding two amyloglucosidase concentrations (3 and 6 UL-1). Adsorption of the heavy metals Zn2+, Cd2+ and Pb2+ was assessed in a single component system using synthetic metal solutions and as a function of the initial concentration of adsorbate, equilibrium time and removal efficiency. The Langmuir and Freundlich adsorption models were used for the mathematical description of the biosorption equilibrium and isotherm constants. A pseudo second-order model was applied to describe the uptake rate for two isolates. The EnBase(A (R)) Flo technology improved the cells growth over ten times after 24 h of fed-batch cultivation. The EnBase(A (R)) Flo technology improved the Cd2+ and Pb2+ uptake capacity of the bacterial strains by approximately 55 and 44 %, respectively. The biosorption of each metal was fairly rapid (within 30 min), which could be an advantage for large scale treatment of contaminated sites. This initial study may be a basis for future developments to apply EnBase Flo for the biomass production used further as biosorbent for heavy metal removal from aqueous solutions.