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    Enhanced production of laccase by fungi under solid substrate fermentation condition
    (2011) Boran F.; Yeşilada O.
    Funalia trogii and Trametes versicolor were grown on agro byproduct wheat bran moistened with various natural moistening agents, and their effects on laccase production under solid substrate condition were investigated. Laccase was the main enzyme detected under this condition. High levels of laccase activity were obtained with solid substrate cultures moistened with olive oil mill wastewater (OOMW) or alcohol factory wastewater (vinasse). Among the cultures without inducer, T. versicolor culture was detected as a more effective laccase producer than F. trogii culture. Copper and xylidine were used as laccase inducers, and copper induced laccase production more than xylidine. The maximum laccase activity was detected as 14.18 U/mL with F. trogii grown on wheat bran moistened with 5 mM CuSO 4.5H 2O added 25% vinasse. Azo dye decolorization activity of the supernatants from solid substrate cultures was also tested. While the use of 0.063 U/mL F. trogii laccase in reaction solution gave 66% decolorization in a minute, it was 14% for T. versicolor. This method can be a possible alternative for valorization of lignocellulosic materials and industrial wastewaters during solid substrate fermentation and for obtaining enzyme source with very high decolorization activity.
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    Influence of the medium conditions on enzymatic oxidation of bisphenol A
    (2014) Yalçinkaya Z.; Gün S.; Şahan T.; Birhanli E.; Sahiner N.; Aktaş N.; Yeşilada O.
    A multistep response surface methodology (RSM) was successfully applied to optimise the medium conditions for the enzymatic polymerisation of bisphenol A (BPA). The laccase enzyme used as the catalyst was derived from Funalia trogii (ATCC 200800) yeast culture. The enzymatic polymerisation rate of BPA, based on the measurements of the initial dissolved oxygen (DO) consumption rate in a closed batch system, was studied through RSM. Initially the most effective medium factors, which are monomer concentration (mg/L), temperature (°C) and solvent content (% methanol), were determined through Plackett-Burman Design (PBD), then the steepest ascent combined with central composite design (CCD) steps were applied to evaluate the optimal reaction conditions for the enzymatic polymerisation. The optimal conditions were evaluated to be 748.46mg/L, 32.24°C and 15.92% for monomer concentration, temperature and solvent content, respectively. A quadratic model was developed through RSM to represent DO consumption in the medium. The maximum DO consumption rate was calculated to be 0.093mg DO/Lmin. Several repetitions were conducted at the optimal conditions to validate the system performance. The data evaluated from the quadratic model were in good agreement with those measured experimentally. The variations between the values did not exceed 10%. The correlation coefficient, R2, was calculated to be 0.95, which indicates that 95% of results can be explained by model. © 2013 Canadian Society for Chemical Engineering.