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Biotransformation of phenolic compounds by bacterium Schlegelella thermodepolymerans
Opial, Tomáš ; Dvořák,, Pavel (referee) ; Obruča, Stanislav (advisor)
The diploma thesis deals with the optimization of the biotransformation of ferulic acid into sensory active substances and production of P3HB by bacterium Schlegelella thermodepolymerans. Cultivation experiments were performed in a medium with various concentrations of ferulic acid. Four bacterial strains were used for these experiments. Attention was paid to the model strain DSM 15344, in which a bioinformatic analysis of genes encoding enzymes, that catalyzed the biotransformation reactions of ferulic acid was also performed. Ferulic acid metabolites, specifically sensory active substances such as vanillyl alcohol, vanillic acid, vanillin and 4-vinylguaiacol, were measured by HPLC. S. thermodepolymerans DSM 15344 exhibited a very fast utilization of ferulic acid already within 8 hours of cultivation. The highest yields of ferulic acid metabolites were detected between 8 and 24 hours depending on the initial concentration of ferulic acid. The main metabolites of ferulic acid were vanillic acid and vanillyl alcohol. Vanillic acid reached the highest concentration in 16 hours in the presence of ferulic acid at initial concentration of 0.5 g/l. The highest yield of vanillyl alcohol occurred in 8 hours with ferulic acid at initial concentration of 0.75 g/l. In addition to biotransformation to ferulic acid, the amount of produced P3HB was also measured by GC-FID. Schlegelella thermodepolymerans DSM 15344 produced the highest amount of P3HB at 72 h at the lowest initial concentration of ferulic acid (0.25 g/l). Within the bioinformatic analysis, the presence of one fcs gene was confirmed using the available databases and the BLAST tool, but this was not enough to construct the complete metabolic pathway of ferulic acid by the bacterium S. thermodepolymerans DSM 15344.
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