Abstract

Lactic acid bacteria (LAB) have been reported to remove heavy metals. The removal of heavy metals, from aqueous solution by LAB has been observed to be strain dependent. In this study, statistical designs were performed to optimize the conditions required for metal biosorption by Oenococcus oeni PSU1. A screening experiment revealed that O. oeni PSU-1 biosorp Cu²⁺ with a high percentage (28%), in comparison to other heavy metals. The Plackett-Burman design was applied and eleven variables were examined. The increase in Cu²⁺ biosorption was mainly affected by Cu²⁺ concentration, cell immobilization and mixing speed. These three variables were further adopted by the three-level Box–Behnken design to correlate between the three variables and to estimate the optimal conditions required for Cu²⁺biosorption. Although the maximum value for Cu²⁺ biosorption was 85%, the calculated optimum percentage was 72%, which was a 2.57-fold increase over that in basal medium. The estimated optimum values for Cu²⁺ biosorption are as follows: metal concentration (8.6 mg/ml), mixing speed (136 rpm) and immobilization (2.27%).

Key words: Oenococcus oeni PSU-1, metal biosorption, Plackett-Burman, Box-Behnken.