Bioaugmentation of carbofuran residues in soil using Burkholderia cepacia PCL3 adsorbed on agricultural residues

Abstract

Burkholderia cepacia PCL3 (GenBank accession number of EF990634) is a carbofuran degrader isolated from phytoremediated rhizosphere soil in our laboratory. Free and the immobilized PCL3 on corncob and sugarcane bagasse were investigated for their abilities to degrade carbofuran in Basal Salt Medium (BSM) and soil microcosm. The reusability and survival of immobilized PCL3 in comparison to free cells were also examined. Short half-lives (t 1/2) of carbofuran of 3–4 d in BSM were obtained using the isolate PCL3 in both free and immobilized cell forms. Immobilized cells could survive (10 6–10 7 cfu ml −1) through 30 d of incubation, while the number of free cells decreased continuously after 10 d. Immobilized B. cepacia PCL3 could be reused twice without loss in their abilities to degrade carbofuran in BSM, which suggested an advantage of using immobilized cell over free cell. Free and immobilized cells were augmented into soil and showed an effective capability to remediate carbofuran residues, both of which indicated by 5-folds decrease in carbofuran half-lives in augmented soil. Immobilization of PCL3 on corncob and sugarcane bagasse provided the possibilities of reusing the cells as well as improving the cell survival without decreasing carbofuran degradation activity.