Sugar beet Ca-pectate gel as a cost-effective immobilized-cell matrix for metal biosorption.

Whole bacterial (Pseudomonas putida) and yeast (Saccharomyces cerevisiae) cells were immobilized by entrapment in gel beads of Ca-pectate obtained from sugar beet pulp and gel beads of commercial Ca-alginate (of algal origin). These immobilized-cell particles were tested for Cd2+ removal from dilute aqueous solutions and their mechanical properties were evaluated. Only Ca-pectate gel beads loaded with yeast cells displayed enhanced cadmium-binding efficiency (13.8 mg Cd2+ per g dry matter) as compared to sterile beads (10.7 mg/g). Sterile Ca-pectate gel beads were noticeably more brittle than algal alginate counterparts. The presence of cells reduced the mechanical resistance of both types of beads, however. The practical use of cell-loaded sugar beet Ca-pectate gel as a metal biosorbent is discussed in light of these results.