Anaerobic microbial degradation of the herbicide propanil

The fate of propanil (3,4-dichloropropionanilide) in an anaerobic soil environment was studied. Two mineral salts media, one amended with 0.05% yeast extract and 0.05% tryptone, and both with 33 μg propanil ml^?1, were inoculated with 10% (v/v) soil to establish enrichment cultures. Cultures were incubated at 30°C under an atmosphere of 95% N₂ and 5% CO₂. There was a complete loss of propanil in 15 days in soil enrichment cultures. One degradation product was detected and identified by HPLC and TLC co-chromatography as 3,4-dichloroaniline. Propanil was also degraded in a soil-free medium containing 0.05% yeast extract and 0.05% tryptone and inoculated with supernatant from a soil enrichment culture. After 100 days, propanil concentration decreased by 81%; 3,4-dichloroaniline and meta-chloroaniline were produced. No decrease in propanil concentration was detected in soil-free cultures without yeast extract and tryptone. No labeled CO₂ or volatile products were detected after 80 days in soil-free enrichment cultures containing ¹⁴C-ring-labeled propanil.