دانلود رایگان مقاله بهینه سازی پردازش زیستی رنگدانه آستاگزانتین با چهار گونه مخمر

Abstract

The utilization of wheat wastes in order to produce astaxanthin by pigment producer microorganisms, ATCC 90197 (Yamadazyma guilliermondii), ATCC 24060 (Yarrowia lipolytica), ATCC 24202 (Xanthophyllomyces dendrorhous) and ATCC 24259 (Sporidiobolus salmonicolor) using solid state fermentation technique was carried out pursuant to Box-Behnken design (BBD). Incubation temperature, initial pH and moisture content parameters with three levels were generated for each fermentation process of the microorganisms to optimize the astaxanthin bioprocessing. Maximal astaxanthin with the yield of 109.23 µg AX/g WW was produced by ATCC 24202 at the conditions; 20.0 °C temperature, 5.5 pH and 90.0% moisture content. A second optimization for inoculation rate was followed out by steepest ascent method (SAM). It was revealed that one of the major agro-industrial wastes of the whole world, wheat wastes, might be used to produce value-added astaxanthin pigment biotechnologically.

3. Results and discussion

The SSF systems with four yeasts ATCC 90197, ATCC 24060, ATCC 24202 and ATCC 24259 were achieved according to the design matrixes (Table 3). The fermentation periods were settled 12 days for ATCC 24202 and ATCC 24259, 15 days for ATCC 90197 and ATCC 24060. The parameters were optimized based on the maximal yield for each yeast as shown in Table 4. 109.23 mg AX/g WW as the maximum yield by ATCC 24202 and wheat wastes fermentation was obtained at the conditions; 20.0 °C temperature, 5.5 pH and 90.0% moisture content. Johnson and Lewis (1979) reported that higher astaxanthin amount was obtained at 4.5 pH than the amount at 5.5 pH. However, Yuanshuai (2006) indicated that 5.0 pH is selected in most recent studies and a temperature range, 15–20 °C is recommended and for astaxanthin production. Ananda et al. (2011) stated that 66.75 mg astaxanthin per gram wheat bran by ATCC 24202 was reached at the day 11th of the process. The relation between the experimental and the predicted values were stated by statistical evaluation in Table 5. It is seen that the selected model is adequate at the [αo0.1] probability for ‘model’ and ‘lack of fit’ tools for all the yeasts, except ATCC 24060. R2 and adjusted R2 values of ATCC 24259; 0.89 and 0.74 respectively presented more satisfied results. Low standard deviation and coefficient of the variance (C.V.%) values are better results for precision and reliability of the experimental data (Montgomery, 2001; Zou et al., 2013). ATCC 90197 demonstrated the lowest standard deviation and C.V.% values.