Proposed pathways of 2C4NP degradation by different 2C4NP utilizers. Panels: A, Burkholderia sp. strain SJ98 (present study); B, Burkholderia sp. strain SJ98 (13); C, R. imtechensis RKJ 300 (14) and Burkholderia sp. strain RKJ 800 (12); D, Arthrobacter sp. strain SJCon (1). The dash lines in panels A and D indicate the ring cleavage positions. Structures: I, 2C4NP; II, CBQ; III, CHQ; IV, 2-chloro-4-hydroxymuconic semialdehyde; V, PNP; VI, 4-NC; VII, BT; VIII, maleylacetate; IX, HQ; X, 4-hydroxymuconic semialdehyde; XI, acyl chloride.