Application of the response surface methodology (RSM) for optimizing the production of volatile organic compounds (VOCs) by Trichosporon moniliiforme

Response surface methodology (RSM) was applied in optimizing the production of volatile organic compounds (VOCs) by shake-flask cultures of a selected Trichosporon moniliiforme strain (DBVPG 4665). A factorial experiment (23) was designed by setting three parameters at two levels: X1 = incubation time (IT = 72–168 h); X2 = pH (4–7); X3 = l-methionine concentration (l-MET = 5–20 g l−1). On the basis of the results of factorial design, X2 (pH) and X3 (l-MET) were optimized by performing a central composite design (CCD). Second-order polynomial models and response surfaces were obtained for total VOC concentration (VOCl) and for the percentage of dimethyl disulphide (DMDS)/total VOCs (%DMDS). A range of variation of X2 and X3 able to maximize simultaneously both responses has been found. Average final values of responses (VOCl = 4.9 ± 1.3 mg l−1; %DMDS = 97.6 ± 1.1%) were about 532 and 133% of data of central point and were in good agreement with calculated values, thus confirming the reliability of our empirical model in optimizing VOCs production by T. moniliiforme