Fig. 2

4-HCA degradation in strain XC1 of Xcc via the hca gene cluster. a Using the gene cluster PP_3356–PP_3359 which is involved in 4-HCA degradation in Pseudomonas putida, homology analysis identified a putative 4-HCA degradation gene cluster, hca in Xcc (colored arrows). hcaL encodes a putative 4-hydroxycinnamoyl-CoA ligase; hcaD encodes a benzaldehyde dehydrogenase; hcaH encodes a 4-hydroxycinnamoyl-CoA hydratase/lyase, and hcaR encodes a MarR-family transcriptional regulator. The numbers inside the parentheses indicate the amino acid identity. b Growth time course of XC1 and XC1-derived mutants in NYG medium supplemented with 50 μM 4-HCA. c Time course for 4-HCA production by strain XC1, XC1-derived mutants and restored mutants in NYG cultures supplemented with 50 μM 4-HCA. d A simple schematic diagram of 4-HBA synthesis, utilization and degradation processes in Xcc. e Time course of 4-HCA and 4-HBA production of strains ΔxanB2ΔxanA2ΔpobA (ΔIII) and ΔxanB2ΔxanA2ΔpobAΔhcaL (ΔIIIΔhcaL). f The proposed 4-HCA degradation pathway in Xcc. For the data in (b, c and e), three independent experiments were conducted for each and the averages with standard deviations are shown