ABSTRACT
Background and Objective: Microbial protein production can resolve one of the major world challenges, i.e. lack of protein sources. Candida tropicalis growth was investigated to specify a medium to reach the highest cell proliferation and protein production
Material and Methods: Fractional factorial design and the index of signal to noise ratio were applied for optimization of microbial protein production. Optimization process was conducted based on the experimental results of Taguchi approach designs. Fermentation was performed at 25[degree sign]C and the agitation speed of 300 rpm for 70 h. Ammonium sulfate, iron sulfate, glycine and glucose concentrations were considered as process variables. Optimization of the culture medium composition was conducted in order to obtain the highest cell biomass concentration and protein content. Experiment design was performed based on the Taguchi approach and L[-1]6 orthogonal arrays using Qualitek-4 software
Results and Conclusion: Maximum biomass of 8.72 log [CFU ml[-1]] was obtained using the optimized medium with 0.3, 0.15, 2 and 80 g l[-1] of ammonium sulfate, iron sulfate, glycine and glucose, respectively. Iron sulfate and ammonium sulfate with 41.76% [w w[-1]] and 35.27% [w w[-1]] contributions, respectively, were recognized as the main components for cell growth. Glucose and glycine with 17.12% and 5.86% [w w[-1]] contributions, respectively, also affected cell production. The highest interaction severity index of +54.16% was observed between glycine and glucose while the least one of +0.43% was recorded for ammonium sulfate and glycine. A deviation of 7% between the highest predicted cell numbers and the experimented count confirms the suitability of the applied statistical method. High protein content of 52.16% [w w[-1]] as well as low fat and nucleic acids content suggest that Candida tropicalis is a suitable case for commercial processes