Fig. 6

UHPLC chromatograms of 1 g/L depolymerized lignin on day 0, 4 and 14 after high cell density bacterial conversion by a R. opacus b, c P. fluorescens d P. putida EM42 e non-inoculated control in M9 medium. The peaks at retention time 1.6, 2.4, 3.5, 4.6 and 4.7 min were identified as 4-HBA, vanillate, vanillin, guaiacol and acetovanillone, respectively. The occurrence of new large peaks at retention times 0.4–0.5 min for P. fluorescens on day 14 are highlighted with a green arrow. For a better visibility of the newly formed peaks on day 14, the chromatograms are arranged in reverse order (bottom to top) for b, c