The propagation of the yeast Saccharomyces cerevisiae was optimized using a Taguchi parameter design (TPD) L9(3 4) to produce bioethanol from an amylaceous material. The response factor selected was the specific growth rate of the yeast as calculated from the slope of the linear portion of its growth curve (neperian log cell concentration versus time). The reason is that the greater this rate, the higher the number of viable cells in the fermentation broth capable of ethanol production. The control factors selected were the initial amount of inoculum in the medium, the amount of glucose, the temperature, and the shaking speed which are the chemical and physical variables that most affect the growth behavior of this yeast. The noise factor selected was the initial peptone concentration in the medium. Statistical analysis and factorial split-plots indicate that the factor that most affected the response was the inoculum concentration (50.79% contribution), followed by the glucose concentration (25.22%), and shaking speed (14.79%). The contribution of temperature to the response variable was small (2.85%). This result was independent of the uncontrolled variation in the percentage of peptone in the sample…
Tag: <span>peptone</span>
The impact of individual and interactive behaviors of various fermentation process parameters on laccase and peroxidase-free tyrosinase production were investigated by isolated Streptomyces antibioticus RSP-T1. Six key bioprocess factors (medium pH, rpm, incubation time, sodium chloride concentration, complex nitrogen [yeast extract + peptone], and carbon source [maltose]) were selected based on using a one variable at a time methodology. All selected parameters had an impact at individual and interactive levels on tyrosinase production. Only 25% of the improved tyrosinase production was attributed to the optimized fermentation parameters selected. Regarding the nutritional parameters, the complex nitrogen/carbon source concentration (maltose and yeast extract + peptone) was found to have the most significance impact on overall tyrosinase enzyme production. Physiological growth factors (pH, rpm, and incubation time) played key roles at an interactive level. A maximum yield of 12.60 IU/mL tyrosinase production was achieved with optimized medium, adjusted to 7.5 pH, consisting of 0.75% maltose (w/v), 0.2% yeast extract (w/v), 0.2% peptone (w/v), and 1.25% sodium chloride (w/v) at 160 rpm in 24 hours. This study identified the optimum medium component concentrations for improved tyrosinase production by S. antibioticus RSP-T1. This strain requires complex nitrogen sources (yeast extract and peptone) for increased product yield. Overall, a greater than 250% increase in tyrosinase production was achieved using this optimization approach, as compared to conventional methods…