Addendum: Polyvinyl chloride degradation by a bacterium isolated from the gut of insect larvae

In our published article 1 , we reported that a purified catalase-peroxidase from Klebsiella sp.EMBL-1 displayed PVC depolymerization activity.However, Stepnov et al. 2 have recently reported that their attempts to replicate our experiments failed to provide any evidence of PVC oxidation or depolymerization activity.Moreover, they concluded that the FTIR peaks that we claimed to indicate enzymatic oxidation of PVC resulted from adsorbed residual protein and not from PVC oxidation 2 .We repeated the catalase-peroxidase enzymatic assays and the FTIR analyses, but this time we failed to detect any significant reduction in PVC molecular weight or any potential degradation products.Moreover, based on the overall evidence, we cannot rule out the possibility that the differences in FTIR peaks may be attributable to residual characteristic peaks of the enzyme itself, rather than to the action of catalase-peroxidase on PVC as we previously claimed.We believe that the potential PVC degradation products detected by GC-MS in our earlier experiments might be attributable to unstable components in the self-prepared PVC powder rather than the enzyme's activity.In summary, any potential roles played by the catalase-peroxidase from Klebsiella sp.EMBL-1 on PVC degradation remains unclear.However, all other findings in our original article 1 remain valid.In addition, our article 1 included an error in the "Methods" (section titled 'Preparation of pure PVC polymer'), in which an incorrect sentence 'All treatments were repeated three times and cultured in a shake (150 rpm, 30 C) for 96 h' should read 'All treatments were repeated three times, provided with 100 M H 2 O 2 at 0, 24 and 48 h, and cultured in a shake (150 rpm, 30 C) for 96 h'.This error has not been corrected in the original article.