Bioprocess design for the microbial production of natural phenolic compounds by Debaryomyces hansenii.

Debaryomyces hansenii NRRL Y-7426 metabolised ferulic acid into different phenolic compounds using a factorial design where glucose concentration (in the range of 1-20 g/L), peptone concentration (2-20 g/L) and yeast extract concentration (0.2-10 g/L) were the independent variables. The interrelationship between dependent and operational variables was well fitted (R (2) > 0.95) to models including linear, interaction and quadratic terms. Depending on the glucose and nitrogen concentrations, which redirected the metabolism, the major degradation products were 1,226.2 mg 4-vinyl guaiacol/L after 72 h (molar yield of 86.0 %), 1,077.8 mg vanillic acid/L after 360 h (molar yield of 91.1 %) or 1,682.6 mg acetovanillone/L after 408 h (molar yield of 98.8 %) in fermentations carried out with 2,000 mg ferulic acid/L. Other metabolites such as vanillin, vanillyl alcohol or 4-ethylguaiacol were present in lower amounts.