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Statistical optimization of process variables for antibiotic activity of Xenorhabdus bovienii.

Fang XL, Han LR, Cao XQ, Zhu MX, Zhang X, Wang YH - PLoS ONE (2012)

Bottom Line: A 2(5-1) factorial central composite design was chosen to determine the combined effects of the five variables, and to design a minimum number of experiments.Statistical analysis of the results showed that initial pH, medium volume, rotary speed and temperature had a significant effect (P<0.05) on the antibiotic production of X. bovienii YL002 at their individual level; medium volume and rotary speed showed a significant effect at a combined level and was most significant at an individual level.After optimization, the antibiotic activity was improved by 23.02% as compared with that of unoptimized conditions.

View Article: PubMed Central - PubMed

Affiliation: Research and Development Center of Biorational Pesticides, Northwest A & F University, Yangling, Shaanxi, People's Republic of China.

ABSTRACT
The production of secondary metabolites with antibiotic properties is a common characteristic to entomopathogenic bacteria Xenorhabdus spp. These metabolites not only have diverse chemical structures but also have a wide range of bioactivities of medicinal and agricultural interests. Culture variables are critical to the production of secondary metabolites of microorganisms. Manipulating culture process variables can promote secondary metabolite biosynthesis and thus facilitate the discovery of novel natural products. This work was conducted to evaluate the effects of five process variables (initial pH, medium volume, rotary speed, temperature, and inoculation volume) on the antibiotic production of Xenorhabdus bovienii YL002 using response surface methodology. A 2(5-1) factorial central composite design was chosen to determine the combined effects of the five variables, and to design a minimum number of experiments. The experimental and predicted antibiotic activity of X. bovienii YL002 was in close agreement. Statistical analysis of the results showed that initial pH, medium volume, rotary speed and temperature had a significant effect (P<0.05) on the antibiotic production of X. bovienii YL002 at their individual level; medium volume and rotary speed showed a significant effect at a combined level and was most significant at an individual level. The maximum antibiotic activity (287.5 U/mL) was achieved at the initial pH of 8.24, medium volume of 54 mL in 250 mL flask, rotary speed of 208 rpm, temperature of 32.0°C and inoculation volume of 13.8%. After optimization, the antibiotic activity was improved by 23.02% as compared with that of unoptimized conditions.

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Desirability charts of variables for maximum response.
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pone-0038421-g004: Desirability charts of variables for maximum response.

Mentions: The desirability function to obtain an optimal antibiotic activity was fitted by the least square method assigning the antibiotic activity at the observed low (113.44 U/mL) and high (268.12 U/mL) values for a corresponding desirability of 0 and 1, respectively, and the profiles were plotted. These desirability profiles show which levels of predicted variables (viz. X1, X2, X3, X4 and X5) produce the most desirable predicted responses on the dependent variable (Y). The profiles for predicted response and the desirability level for variables (Fig. 4) indicated that pH of 8.24, medium volume of 54 mL, rotary speed of 208 rpm, temperature of 32°C and inoculation volume of 13.8% gave maximum antibiotic activity at an optimal desirability score of 1 (Fig. 4). These profiles also suggested that an increase in the pH, medium volume, rotary speed, temperatures and inoculation volume above the optimized levels will decrease the antibiotic activity.


Statistical optimization of process variables for antibiotic activity of Xenorhabdus bovienii.

Fang XL, Han LR, Cao XQ, Zhu MX, Zhang X, Wang YH - PLoS ONE (2012)

Desirability charts of variables for maximum response.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3368850&req=5

pone-0038421-g004: Desirability charts of variables for maximum response.
Mentions: The desirability function to obtain an optimal antibiotic activity was fitted by the least square method assigning the antibiotic activity at the observed low (113.44 U/mL) and high (268.12 U/mL) values for a corresponding desirability of 0 and 1, respectively, and the profiles were plotted. These desirability profiles show which levels of predicted variables (viz. X1, X2, X3, X4 and X5) produce the most desirable predicted responses on the dependent variable (Y). The profiles for predicted response and the desirability level for variables (Fig. 4) indicated that pH of 8.24, medium volume of 54 mL, rotary speed of 208 rpm, temperature of 32°C and inoculation volume of 13.8% gave maximum antibiotic activity at an optimal desirability score of 1 (Fig. 4). These profiles also suggested that an increase in the pH, medium volume, rotary speed, temperatures and inoculation volume above the optimized levels will decrease the antibiotic activity.

Bottom Line: A 2(5-1) factorial central composite design was chosen to determine the combined effects of the five variables, and to design a minimum number of experiments.Statistical analysis of the results showed that initial pH, medium volume, rotary speed and temperature had a significant effect (P<0.05) on the antibiotic production of X. bovienii YL002 at their individual level; medium volume and rotary speed showed a significant effect at a combined level and was most significant at an individual level.After optimization, the antibiotic activity was improved by 23.02% as compared with that of unoptimized conditions.

View Article: PubMed Central - PubMed

Affiliation: Research and Development Center of Biorational Pesticides, Northwest A & F University, Yangling, Shaanxi, People's Republic of China.

ABSTRACT
The production of secondary metabolites with antibiotic properties is a common characteristic to entomopathogenic bacteria Xenorhabdus spp. These metabolites not only have diverse chemical structures but also have a wide range of bioactivities of medicinal and agricultural interests. Culture variables are critical to the production of secondary metabolites of microorganisms. Manipulating culture process variables can promote secondary metabolite biosynthesis and thus facilitate the discovery of novel natural products. This work was conducted to evaluate the effects of five process variables (initial pH, medium volume, rotary speed, temperature, and inoculation volume) on the antibiotic production of Xenorhabdus bovienii YL002 using response surface methodology. A 2(5-1) factorial central composite design was chosen to determine the combined effects of the five variables, and to design a minimum number of experiments. The experimental and predicted antibiotic activity of X. bovienii YL002 was in close agreement. Statistical analysis of the results showed that initial pH, medium volume, rotary speed and temperature had a significant effect (P<0.05) on the antibiotic production of X. bovienii YL002 at their individual level; medium volume and rotary speed showed a significant effect at a combined level and was most significant at an individual level. The maximum antibiotic activity (287.5 U/mL) was achieved at the initial pH of 8.24, medium volume of 54 mL in 250 mL flask, rotary speed of 208 rpm, temperature of 32.0°C and inoculation volume of 13.8%. After optimization, the antibiotic activity was improved by 23.02% as compared with that of unoptimized conditions.

Show MeSH