Mycoprotein production by Fusarium venenatum in surface culture using a central composite design

Due to their nutritional, physical and chemical characteristics, mycoproteins, produced in the process of fungal growth, have been proposed to be used as a food additive for man. In this study a central composite design was applied to assessing the effect of seed size and initial concentrations of carbon and nitrogen sources on mycoprotein production by Fusarium venenatum [ATCC20334] from date sugar. Chemical composition [percent dried cell weight, nitrogen, moisture, and ash] and pH of the substrate were determined. Vogel culture medium was used for maintenance and inoculum preparation, and incubation was done at 30 °C for 72h. Dried cell weight was measured by the oven method. The experimental results were fitted to a full quadratic second order polynomial equation and the optimization of response was done with Minitab 14 software. Optimum conditions were determined and a confirmation test was conducted. The regression coefficient of the model presented for mycoprotein production [based on dried cell weight] was 98.0%. The optimum conditions for the mycoprotein production included a seed size of 15.39% v/v, and a carbon and nitrogen source of 20 and 4.35 g/L, respectively. The predicted value for the optimum production of dried biomass was 5.032 g/L. The reconfirmation test was conducted at the optimum conditions and the result obtained was 4.84 g/L of biomass production. The regression coefficient indicates accuracy and suitability of the model for the experimental data. By changing the inoculum conditions and the chemical composition of the culture medium, optimal growth of Fusarium venenatum and, consequently, maximum biomass production, can be achieved. Use of date syrup as an available and domestic Iranian substrate for modification of Vogel medium makes possible protein production at an industrial scale in surface culture

[Comparison of bench-scale production of xanthan by xanthomonas campestris in solid state and submerged fermentation]

Xanthan gum is an important natural biopolymer with numerous applications in various technologies, specially food industry. In this research, microbial production of xanthan by Xanthomonas campestris PTCC1473 from sugarcane molasses and date sugar in submerged fermentation [SmF] and also dried date waste [cake produced after pressing] in solid state fermentation [SSF] were compared. The Plackett-Burmann design [PBD] was used in this study. Chemical composition and characteristics [dried cell weight, nitrogen, moisture, ash and pH] of the substrates were determined. Yeast malt broth [YMB] and yeast malt agar [YMA] were used as maintenance and inoculum preparation media, and incubation was performed in a shaker incubator [at 28degreeC, 72 h and 200 rpm]. The fermentation medium was centrifuged at 5degreeC and 21055 multiplied by g for 50 minutes and the supernatant separated from the pellet for further xanthan extraction. After precipitation of xanthan by isopropanol, resuspension and further purification by centrifuge [at 2056 x g], the xanthan dry weight was determined. The effects of several variables, including the kind and concentration of carbon [date sugar and sugarcane molasses], nitrogen [ammonium nitrate and diammonium phosphate] and phosphorus [KH2PO4], temperature, shaking, and size and age of inoculum, on the yield were determined. The most effective variables were found to be the type of carbon and nitrogen sources in the medium. It can be concluded that both the yield [% w/w of xanthan/consumed sugar] and productivity [g/g.day xanthan/consumed sugar] are higher in SmF [22.4 and 7.46] than in SSF [13.3 and 4.43]. In addition, date extract results in a higher productivity than date waste and sugarcane molasses. The xanthan yield could be increased by changing the composition and physical conditions of the culture medium