Optimization of laccase production by Botryosphaeria sp in the presence of veratryl alcohol by the response-surface method

Botryosphaeria sp. produced two laccases (PPO-I and PPO-II) constitutively, whose titers were enhanced by veratryl alcohol. The effect of veratryl alcohol and yeast extract concentration, time of cultivation and agitation speed were evaluated by factorial analysis to select variables for optimizing the production of laccases. Maximal laccase production was determined using a second-order central-composite design and analyzed by the response-surface method. Veratryl alcohol concentration and time of cultivation were the main factors increasing laccase production, while yeast extract had no influence within the range 0.2-2.0% w/v. Response-surface analysis showed that 30.4 mM veratryl alcohol, for 4.5 days at 28 degrees C and 180 rpm, were the optimal conditions to maximize PPO-I production, while conditions for maximal PPO-II production occurred within a range of 28-35 mM veratryl alcohol over a growth period of 4-5.5 days. The model predicted 5.6 U ml(-1) for PPO-I, and 0.6-1.0 U ml(-1) for PPO-II, which agreed with the experimentally observed results. (C) 2000 Elsevier Science Ltd. All rights reserved.