Optimization for biopolymer production by Enterobacter cloacae WD7

Prasertsan, Poonsuk, Wichienchot, Santad, Doelle, Horst and Kennedy, John F. (2008) Optimization for biopolymer production by Enterobacter cloacae WD7. Carbohydrate Polymers, 71 3: 468-475. doi:10.1016/j.carbpol.2007.06.017

Author Prasertsan, Poonsuk
Wichienchot, Santad
Doelle, Horst
Kennedy, John F.
Title Optimization for biopolymer production by Enterobacter cloacae WD7
Formatted title
Optimization for biopolymer production by Enterobacter cloacae WD7
Journal name Carbohydrate Polymers   Check publisher's open access policy
ISSN 0144-8617
Publication date 2008-02-08
Sub-type Article (original research)
DOI 10.1016/j.carbpol.2007.06.017
Volume 71
Issue 3
Start page 468
End page 475
Total pages 8
Place of publication East Park, Kidlington, Oxford, U.K.
Publisher Pergamon
Language eng
Formatted abstract
Factors affecting the production of exopolysaccharide (EPS) from Enterobacter cloacae WD7 cultivated in basal medium (pH 7.0) using 1% w/v glucose as a carbon source for 5 days at 30°C were investigated. The EPS yield of 2.23 g L−1 was obtained after 3 days cultivation. Among the carbon sources tested, 3% sucrose was selected and gave an EPS yield of 2.72 g L−1. This indicated that sucrose is a better carbon source than the glucose used previously. The addition of either inorganic nitrogen [(NH4)2SO4, NH4Cl and NH4NO3] or organic nitrogen (polypeptone) sources had no effect on the EPS yield. The optimum concentration of yeast extract was found to be 0.05% w/v. The optimum environmental conditions were: initial pH 7.0, temperature 30°C, pH control at 7.0 and the aeration rate of 2.0 vvm which elevated the EPS yield to 4.80 g L−1 while further increase in the agitation speed (200 rpm) reduced the production of EPS. Comparison of the kinetic parameters of the shake-flask and batch fermentations revealed that batch fermenter culture gave about 2 times higher values of specific growth rate (μ = 0.15 and 0.29 h−1), product yields (Yp/s = 0.25 and 0.52 g EPS g sucrose−1) and maximum productivity (Rm = 0.04 and 0.07 g of EPS L−1 h−1). Substitution of the analytical grade sucrose by commercial sucrose resulted in 15% lower EPS yield (i.e. from 4.90 to 4.18 g L−1, respectively) but could lower the raw material cost by 98%, and therefore is a suitable component for the production medium. For continuous culture studies, the optimum dilution rate was 0.05 h−1 giving the maximum EPS concentration of 7.28 g L−1 which is 1.5 times higher than the batch culture and a total of 3.2 times higher than the beginning (2.23 g L−1). The critical dilution rate (Dc) was calculated to be 0.49 h−1 with the maximum dilution rate (Dm) of 0.485 h−1, Yx/s of 0.03 g cell/g sucrose and the Rm of 0.06 g EPS L−1 h−1. Batch culture therefore gave a slightly higher productivity and would be the method of choice for scale-up studies.
Keyword Optimization
Exopolysaccharide production
Enterobacter cloacae
Batch culture
Continuous culture
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Biological Sciences Publications
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Citation counts: TR Web of Science Citation Count  Cited 25 times in Thomson Reuters Web of Science Article | Citations
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Created: Thu, 03 Sep 2009, 10:27:49 EST by Mr Andrew Martlew on behalf of Microbiology and Parasitology, Department of