Characterization and Identification of A Sludge-Associated Bacterial Isolate

During a metal speciation study, an unusually high retention of lead ·was observed when lead solution was percolated through a column packed with sludge compost obtained from Hampton Roads Sanitation department. A bacterium was isolated from the sludge compost and identified as Bacillus sphaericus using electron microscopy, whole cell fatty acid analysis (Midi System) and Biolog GP Microplate. The isolate grows in broth and agar media containing up to 800 μM lead. Lead accumulation study using atomic absorption spectrophotometer indicates that the isolate adsorbs lead. Lead adsorption is pH dependent. The isolate contains a plasmid of approximately 40 -50 kbp that might be involved in resistance to lead. Studies are in progress to characterize this plasmid. The bacterial isolate has the potential of being used in bioremediation of heavy metal contaminated water and could be involved in localized accumulation of lead in gardens if heavy metal contain­ ing sludge compost is used as fertilizer.