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Optimization of fermentation conditions and properties of an exopolysaccharide from Klebsiella sp. H-207 and application in adsorption of hexavalent chromium.

Qiang L, Yumei L, Sheng H, Yingzi L, Dongxue S, Dake H, Jiajia W, Yanhong Q, Yuxia Z - PLoS ONE (2013)

Bottom Line: The resulting product showed good properties, such as high concentration of uronic acid (41.67%), low average molecular weight (about 1.94×10(5) Da) and porous surface structure, were very advantageous to biosorption.Therefore HZ-7 was applied to absorb hexavalent chromium (Cr(VI)).These data suggest Klebsiella sp.

View Article: PubMed Central - PubMed

Affiliation: School of Medicine and Life Sciences, University of Jinan, Jinan, China. chm_ lq@ujn.edu.cn

ABSTRACT
The novel exopolysaccharide HZ-7 is produced by Klebsiella sp. H-207, and its fermentation conditions were optimized by response surface methodology (RSM). In this study, the optimized medium consisted of sucrose 31.93 g/L, KNO(3) 2.17 g/L and K(2)HPO(4) 5.47 g/L; while the optimized culture conditions consisted of seed age 13 h, with an inoculum size of 10.6% and incubation temperature of 28.9°C. A maximum HZ-7 yield of about 15.05 g/L was achieved under the optimized conditions using RSM and single-factor experiments. Next the exopolysaccharide HZ-7 was partially purified and characterized. The resulting product showed good properties, such as high concentration of uronic acid (41.67%), low average molecular weight (about 1.94×10(5) Da) and porous surface structure, were very advantageous to biosorption. Therefore HZ-7 was applied to absorb hexavalent chromium (Cr(VI)). The maximum adsorption efficiency (99.2%) which was obtained at an initial pH of 1.0 along with an initial Cr(VI) concentration of 20 mg/L, was not affected by ordinary metal ions and temperature. These data suggest Klebsiella sp. H-207 exopolysaccharide will be promising potential for industrial application.

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Response surface plots of the effect of three variables in medium on HZ-7 production.A, interaction of sucrose (X1, g/L) and KNO3 (X2, g/L); B, interaction of sucrose (X1, g/L) and K2HPO4 (X3, g/L); C, interaction of KNO3 (X2, g/L) and K2HPO4 (X3, g/L).
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pone-0053542-g003: Response surface plots of the effect of three variables in medium on HZ-7 production.A, interaction of sucrose (X1, g/L) and KNO3 (X2, g/L); B, interaction of sucrose (X1, g/L) and K2HPO4 (X3, g/L); C, interaction of KNO3 (X2, g/L) and K2HPO4 (X3, g/L).

Mentions: The statistical significance of equation (3) was evaluated by the F-test and ANOVA analysis (Table 2). The three-dimensional graphs based on Equation (3) were shown in Figure 3. The equation was very reliable with an R2 value of 0.9975, which indicated that 99% of the variability in the response could be explained by this model. As shown in Table 2, the ‘Model F-value’ of 222.31 implied that the model was significant, and there was only a 0.01% chance that a ‘Model F-value’ could occur due to noise (P<0.0001). The low coefficient of variation (CV) of 1.6% also indicated that the model was reliable. Values of ‘prob>F’ less than 0.05 indicated the model terms were significant. In this case, coded values X1, X2, X3, X12, X22 and X32 were significant model terms. The interaction of X1X2 (sucrose/KNO3) was not significant (P>0.05), however, a substantial amount of sucrose was necessary for HZ-7 production (Figure 3A). On the other hand the interactive effect of K2HPO4/sucrose (X1X3) and K2HPO4/KNO3 (X2X3) on HZ-7 production were significant (P<0.05), which implied potassium and phosphate were crucial to HZ-7 synthesis (Figure 3B, C). According to the canonical analysis, the optimal concentrations of sucrose, KNO3 and K2HPO4 were 31.93 g/L, 2.17 g/L and 5.47 g/L, respectively. The maximum yield was estimated to be 13.54 g/L, and the actual yield obtained with the optimal medium was 13.42 g/L (the average value of triple experiments), which was in close accordance with the model prediction. In addition, the sole nitrogen source and mineral salt were used in the fermentation medium for maximum HZ-7 production, which would be advantage to reduce production cost and operation process of EPS. Also, this medium composition for EPS production was simplest among present reports which consisted of complex nitrogen sources or multiple mineral [23]–[26].


Optimization of fermentation conditions and properties of an exopolysaccharide from Klebsiella sp. H-207 and application in adsorption of hexavalent chromium.

Qiang L, Yumei L, Sheng H, Yingzi L, Dongxue S, Dake H, Jiajia W, Yanhong Q, Yuxia Z - PLoS ONE (2013)

Response surface plots of the effect of three variables in medium on HZ-7 production.A, interaction of sucrose (X1, g/L) and KNO3 (X2, g/L); B, interaction of sucrose (X1, g/L) and K2HPO4 (X3, g/L); C, interaction of KNO3 (X2, g/L) and K2HPO4 (X3, g/L).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3539975&req=5

pone-0053542-g003: Response surface plots of the effect of three variables in medium on HZ-7 production.A, interaction of sucrose (X1, g/L) and KNO3 (X2, g/L); B, interaction of sucrose (X1, g/L) and K2HPO4 (X3, g/L); C, interaction of KNO3 (X2, g/L) and K2HPO4 (X3, g/L).
Mentions: The statistical significance of equation (3) was evaluated by the F-test and ANOVA analysis (Table 2). The three-dimensional graphs based on Equation (3) were shown in Figure 3. The equation was very reliable with an R2 value of 0.9975, which indicated that 99% of the variability in the response could be explained by this model. As shown in Table 2, the ‘Model F-value’ of 222.31 implied that the model was significant, and there was only a 0.01% chance that a ‘Model F-value’ could occur due to noise (P<0.0001). The low coefficient of variation (CV) of 1.6% also indicated that the model was reliable. Values of ‘prob>F’ less than 0.05 indicated the model terms were significant. In this case, coded values X1, X2, X3, X12, X22 and X32 were significant model terms. The interaction of X1X2 (sucrose/KNO3) was not significant (P>0.05), however, a substantial amount of sucrose was necessary for HZ-7 production (Figure 3A). On the other hand the interactive effect of K2HPO4/sucrose (X1X3) and K2HPO4/KNO3 (X2X3) on HZ-7 production were significant (P<0.05), which implied potassium and phosphate were crucial to HZ-7 synthesis (Figure 3B, C). According to the canonical analysis, the optimal concentrations of sucrose, KNO3 and K2HPO4 were 31.93 g/L, 2.17 g/L and 5.47 g/L, respectively. The maximum yield was estimated to be 13.54 g/L, and the actual yield obtained with the optimal medium was 13.42 g/L (the average value of triple experiments), which was in close accordance with the model prediction. In addition, the sole nitrogen source and mineral salt were used in the fermentation medium for maximum HZ-7 production, which would be advantage to reduce production cost and operation process of EPS. Also, this medium composition for EPS production was simplest among present reports which consisted of complex nitrogen sources or multiple mineral [23]–[26].

Bottom Line: The resulting product showed good properties, such as high concentration of uronic acid (41.67%), low average molecular weight (about 1.94×10(5) Da) and porous surface structure, were very advantageous to biosorption.Therefore HZ-7 was applied to absorb hexavalent chromium (Cr(VI)).These data suggest Klebsiella sp.

View Article: PubMed Central - PubMed

Affiliation: School of Medicine and Life Sciences, University of Jinan, Jinan, China. chm_ lq@ujn.edu.cn

ABSTRACT
The novel exopolysaccharide HZ-7 is produced by Klebsiella sp. H-207, and its fermentation conditions were optimized by response surface methodology (RSM). In this study, the optimized medium consisted of sucrose 31.93 g/L, KNO(3) 2.17 g/L and K(2)HPO(4) 5.47 g/L; while the optimized culture conditions consisted of seed age 13 h, with an inoculum size of 10.6% and incubation temperature of 28.9°C. A maximum HZ-7 yield of about 15.05 g/L was achieved under the optimized conditions using RSM and single-factor experiments. Next the exopolysaccharide HZ-7 was partially purified and characterized. The resulting product showed good properties, such as high concentration of uronic acid (41.67%), low average molecular weight (about 1.94×10(5) Da) and porous surface structure, were very advantageous to biosorption. Therefore HZ-7 was applied to absorb hexavalent chromium (Cr(VI)). The maximum adsorption efficiency (99.2%) which was obtained at an initial pH of 1.0 along with an initial Cr(VI) concentration of 20 mg/L, was not affected by ordinary metal ions and temperature. These data suggest Klebsiella sp. H-207 exopolysaccharide will be promising potential for industrial application.

Show MeSH
Related in: MedlinePlus