Summary Enrichment cultures capable of reductively dechlorinating 1,2,4‐trichlorodibenzo‐ p ‐dioxin (1,2,4‐TrCDD) were shown to dechlorinate 1,2,3‐trichlorobenzene (1,2,3‐TrCB) to 1,3‐dichlorobenzene. To test if this activity can be used to enrich for dioxin‐dechlorinating bacteria, a two‐liquid phase cultivation with 200 mM 1,2,3‐TrCB dissolved in hexadecane was established. During the dechlorination of 1,2,3‐TrCB, the number...