Fig. 8

Degradation of caprolactam in soil by A. citreus. For the study of biodegradation of caprolactam in soil, fertile garden soil was used. 5 g of dry sterile soil (autoclaved twice) or fertile-non sterile soil (10¹¹ cfu of natural soil flora/g dry soil) in 50 ml sterilised vials, was mixed with 10 mg caprolactam and a minimal amount of sterile water, inoculated (filled square) with A. citreus (10⁸ cfu/g soil) and incubated at 30 (± 2) °C for 7 days. Soil not inoculated with culture (filled diamond) was kept as control. By addition of sterile water the soil was kept sufficiently moist. At various time intervals, 5 ml of sterile water was added to the entire system, the contents were vigorously vortexed and the aqueous extract was centrifuged at 10,000×g for 20 min and the supernatant was used for estimation of caprolactam