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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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Response surface plot and contour plot.(A) The combined effect of pH and medium volume on the antibiotic activity of Xenorhabdus bovienii YL002. (B) The combined effect of pH and temperature on the antibiotic activity of X. bovienii YL002. (C) The combined effect of medium volume and rotary speed on the antibiotic activity of X. bovienii YL002.
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pone-0038421-g003: Response surface plot and contour plot.(A) The combined effect of pH and medium volume on the antibiotic activity of Xenorhabdus bovienii YL002. (B) The combined effect of pH and temperature on the antibiotic activity of X. bovienii YL002. (C) The combined effect of medium volume and rotary speed on the antibiotic activity of X. bovienii YL002.

Mentions: Fig. 3A showed the 3D plot and its corresponding contour plot of the effects of initial pH and medium volume on the antibiotic activity while the other three variables were fixed at their middle level. With the increase of the initial pH from 4.0 to 7.0, the antibiotic activity significantly increased from 98.0 to 231.6 U/mL at a low medium volume, but only increased from 100.0 to 180.0.0 U/mL at a high medium volume. This suggests that increasing the initial pH within the tested range was beneficial to the antibiotic production. Our results also showed when the initial pH beyond 7.6, the antibiotic activity decreased. The three-dimensional plot and its respective contour plot facilitated the identification of the optimal levels of initial pH and medium volume. The optimal initial pH was around 7.2, and the medium volume was around 25.0 mL.


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)

Response surface plot and contour plot.(A) The combined effect of pH and medium volume on the antibiotic activity of Xenorhabdus bovienii YL002. (B) The combined effect of pH and temperature on the antibiotic activity of X. bovienii YL002. (C) The combined effect of medium volume and rotary speed on the antibiotic activity of X. bovienii YL002.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0038421-g003: Response surface plot and contour plot.(A) The combined effect of pH and medium volume on the antibiotic activity of Xenorhabdus bovienii YL002. (B) The combined effect of pH and temperature on the antibiotic activity of X. bovienii YL002. (C) The combined effect of medium volume and rotary speed on the antibiotic activity of X. bovienii YL002.
Mentions: Fig. 3A showed the 3D plot and its corresponding contour plot of the effects of initial pH and medium volume on the antibiotic activity while the other three variables were fixed at their middle level. With the increase of the initial pH from 4.0 to 7.0, the antibiotic activity significantly increased from 98.0 to 231.6 U/mL at a low medium volume, but only increased from 100.0 to 180.0.0 U/mL at a high medium volume. This suggests that increasing the initial pH within the tested range was beneficial to the antibiotic production. Our results also showed when the initial pH beyond 7.6, the antibiotic activity decreased. The three-dimensional plot and its respective contour plot facilitated the identification of the optimal levels of initial pH and medium volume. The optimal initial pH was around 7.2, and the medium volume was around 25.0 mL.

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