Design of a fungal bioprocess for vanillin production from vanillic acid at scalable level by Pycnoporus cinnabarinus

The biotechnological process of vanillin production from vanillic acid by P ycnoporus cinnabarinus was scaled-up at the laboratory level. Vanillin prod uction was studied in two types of bioreactors, a mechanically agitated and an air-lift bioreactor. In the mechanically agitated bioreactor where vani llin was produced in greater quantities, oxygen availability was studied du ring the growth and production phases. A maximal aeration rate (90 l/h equi valent to 0.83 volume of air/volume of medium/min or vvm) during the growth phase and a minimal aeration rate (30 l/h equivalent to 0.28 vvm) during t he production phase were necessary to increase vanillin production to 1260 mg/l. Vanillic acid bioconversion to vanillin occurred under the conditions of reduced dissolved oxygen concentration, gentle agitation, high carbon d ioxide production and low specific growth rate. However, under these condit ions, vanillin production was accompanied by a significant amount of methox yhydroquinone. Vanillin over a concentration of 1000 mg/l was shown to be h ighly toxic to the growth of P. cinnabarinus on agar medium. The applicatio n of selective XAD-2 resin led to a reduction of vanillin concentration in the medium, thus limiting its toxicity towards the fungal biomass as well a s the formation of unwanted by-products such as methoxyhydroquinone and all owed the concentration of vanillin produced to reach 1575 mg/l.