Degradation of p-nitrophenol by immobilized cells of Bacillus spp. isolated from soil

Two species of Bacillus, Bacillus pantothenticus and Bacillus aminovorans, capable of degrading p-nitrophenol (PNP), were isolated from soil following selective enrichment. Washed cells of PNP-grown cultures were entrapped in alginate beads and assessed for their potential in degrading PNP. Degradation of PNP by immobilized cells in batch cultures was slow when compared with those in shake cultures. Cells of B. pantothenticus entrapped in 3% calcium alginate were more efficient in degrading PNP than those immobilized in 4 or 5% alginate beads. The rate of PNP degradation by immobilized cells was directly proportional to the stocking density of cells in the beads. The potential of PNP biodegradation in immobilized cells of B. pantothenticus lasted even after two years of storage of the beads in medium supplemented with PNP at refrigerated temperature of 4 °C. Our results clearly indicate that these soil isolates of Bacillus spp. have great potential in bioremediation of aqueous systems contaminated with PNP.

► Soil isolates of Bacillus spp. exhibited great potential in degrading PNP.
► Bacillus pantothenticus entrapped in alginate rapidly removed PNP in shake cultures.
► Entrapment of B. pantothenticus in 3% alginate was effective in degrading PNP.
► Entrapped B. pantothenticus degraded PNP even after two years of storage at 4 °C.