Optimization of Bacillus subtilis cell growth effecting jiean-peptide production in fed batch fermentation using central composite design

Background Optimization of nutrient feeding was developed to improve the growth of Bacillus subtilis in fed batch fermentation to increase the production of jiean-peptide (JAA). A central composite design (CCD) was used to obtain a model describing the relationship between glucose, total nitrogen, and the maximum cell dry weight in the culture broth with fed batch fermentation in a 5 L fermentor. Results The results were analyzed using response surface methodology (RSM), and the optimized values of glucose and total nitrogen concentration were 30.70 g/L and 1.68 g/L in the culture, respectively. The highest cell dry weight was improved to 77.50 g/L in fed batch fermentation, which is 280% higher than the batch fermentation concentration (20.37 g/L). This led to a 44% increase of JAA production in fed batch fermentation as compared to the production of batch fermentation. Conclusion The results of this work improve the present production of JAA and may be adopted for other objective products' production.

Kinetic characteristics of beta-cyclodextrin production by cyclodextrin glycosyltransferase from newly isolated Bacillus sp. C26

The kinetic characteristics of beta-cyclodextrin production by a cyclodextrin glycosyltransferase (CGTase) produced by Bacillus sp. C26, a new isolate from a soil sample was investigated. Considering highest yield and initial production rate of beta-cyclodextrin, among the starches examined, soluble starch, tapioca starch, sago starch, corn starch and rice starch, tapioca starch was the best substrate for this CGTase. The optimum temperature for tapioca starch gelatinization prior to its use as a substrate for beta-cyclodextrin production was 65ºC. The yield and initial production rate of beta-cyclodextrin increased with increasing starch concentration up to 6 percent and an enzyme concentration up to 48 U/g-starch. The kinetic parameters of Vmax and Km of beta-cyclodextrin production from tapioca starch by CGTase were 1.59 mg/mL/h and 22.3 mg/mL, respectively. Considering high initial production rate and high yield of beta-cyclodextrin, the optimum reaction temperature was at 50ºC. This study provided the necessary kinetic information that may be useful to define the most suitable condition for industrialized production of beta-cyclodextrin with the high yield and productivity.

Response surface methodology used for statistical optimization of jiean-peptide production by Bacillus subtilis cells adsorbed on wood chips

Response surface methodology (RSM) was used for statistical optimization of jiean-peptide (JAA) production by Bacillus subtilis ZK8 cells adsorbed on wood chips to form a novel fermentation system. The Plackett-Burman design was used in the first step to evaluate the effects of eight factors, including six fermentation medium components and two cell adsorption conditions. Among the variables screened, soybean meal hydrolysate (SMH) and MgSO4A7H2O in the fermentation medium had significant effects on JAA production. In the second step, the concentrations of SMH and MgSO4A7H2O were further optimized using central composite designs and response surface analysis. The optimized concentration of SMH and MgSO4À7H2O was 24 percent (v/v) and 0.38 percent (w/v), respectively, which increased the production of JAA in a shake flask system by 41 percent relative to optimization of a single variable component of the culture medium.