Improvement of ferulic acid bioconversion into vanillin by use of high-density cultures of Pycnoporus cinnabarinus

High-density cultures of Pycnoporus cinnabarinus were tested with a view to optimisation of ferulic acid bioconversion into vanillin. The dry weight w as increased fourfold by using glucose, fructose or a mixture of glucose an d phospholipids as carbon source instead of maltose, the carbon source prev iously used. 5 mmol l(-1) vanillin, i.e. 760 mg l(-1), was produced over 15 days with glucose-phospholipid medium. In contrast, formation of vanillin was lower using glucose or fructose compared to the maltose control. A bior eactor (2 1) with a glucose-phospholipid medium gave a molar yield of vanil lin of 61% (4 mmol l(-1)). An alternative strategy was to grow the fungus o n a glucose or fructose medium for 3 days, then switch to maltose during th e bioconversion phase: this method allowed 3.3 mmol l(-1) vanillin to be ob tained in 10 days. Many by-products such as methoxyhydroquinone and vanilly l alcohol were also produced.