Immobilization of <it>Acetobacter</it> sp. CCTCC M209061 for efficient asymmetric reduction of ketones and biocatalyst recycling
<p>Abstract</p> <p>Background</p> <p>The bacterium <it>Acetobacter</it> sp. CCTCC M209061 is a promising whole-cell biocatalyst with exclusive anti-Prelog stereoselectivity for the reduction of prochiral ketones that can be used to make valuable chiral alcoh...
| Main Authors: | , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
BMC
2012-09-01
|
| Series: | Microbial Cell Factories |
| Subjects: | |
| Online Access: | http://www.microbialcellfactories.com/content/11/1/119 |
| _version_ | 1828497716685045760 |
|---|---|
| author | Chen Xiao-Hong Wang Xiao-Ting Lou Wen-Yong Li Ying Wu Hong Zong Min-Hua Smith Thomas J Chen Xin-De |
| author_facet | Chen Xiao-Hong Wang Xiao-Ting Lou Wen-Yong Li Ying Wu Hong Zong Min-Hua Smith Thomas J Chen Xin-De |
| author_sort | Chen Xiao-Hong |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Background</p> <p>The bacterium <it>Acetobacter</it> sp. CCTCC M209061 is a promising whole-cell biocatalyst with exclusive anti-Prelog stereoselectivity for the reduction of prochiral ketones that can be used to make valuable chiral alcohols such as (<it>R</it>)-4-(trimethylsilyl)-3-butyn-2-ol. Although it has promising catalytic properties, its stability and reusability are relatively poor compared to other biocatalysts. Hence, we explored various materials for immobilizing the active cells, in order to improve the operational stability of biocatalyst.</p> <p>Results</p> <p>It was found that Ca-alginate give the best immobilized biocatalyst, which was then coated with chitosan to further improve its mechanical strength and swelling-resistance properties. Conditions were optimized for formation of reusable immobilized beads which can be used for repeated batch asymmetric reduction of 4′-chloroacetophenone. The optimized immobilized biocatalyst was very promising, with a specific activity of 85% that of the free-cell biocatalyst (34.66 <it>μ</it>mol/min/g dw of cells for immobilized catalyst <it>vs</it> 40.54 <it>μ</it>mol/min/g for free cells in the asymmetric reduction of 4′-chloroacetophenone). The immobilized cells showed better thermal stability, pH stability, solvent tolerance and storability compared with free cells. After 25 cycles reaction, the immobilized beads still retained >50% catalytic activity, which was 3.5 times higher than degree of retention of activity by free cells reused in a similar way. The cells could be recultured in the beads to regain full activity and perform a further 25 cycles of the reduction reaction. The external mass transfer resistances were negligible as deduced from Damkohler modulus Da < <1, and internal mass transfer restriction affected the reduction action but was not the principal rate-controlling step according to effectiveness factors <it>η</it> < 1 and Thiele modulus 0.3<<it>∅</it> <1.</p> <p>Conclusions</p> <p>Ca-alginate coated with chitosan is a highly effective material for immobilization of <it>Acetobacter</it> sp. CCTCC M209061 cells for repeated use in the asymmetric reduction of ketones. Only a small cost in terms of the slightly lower catalytic activity compared to free cells could give highly practicable immobilized biocatalyst.</p> |
| first_indexed | 2024-12-11T12:52:53Z |
| format | Article |
| id | doaj.art-ab54dd590dab4d2ba07259b27f1c86ec |
| institution | Directory Open Access Journal |
| issn | 1475-2859 |
| language | English |
| last_indexed | 2024-12-11T12:52:53Z |
| publishDate | 2012-09-01 |
| publisher | BMC |
| record_format | Article |
| series | Microbial Cell Factories |
| spelling | doaj.art-ab54dd590dab4d2ba07259b27f1c86ec2022-12-22T01:06:39ZengBMCMicrobial Cell Factories1475-28592012-09-0111111910.1186/1475-2859-11-119Immobilization of <it>Acetobacter</it> sp. CCTCC M209061 for efficient asymmetric reduction of ketones and biocatalyst recyclingChen Xiao-HongWang Xiao-TingLou Wen-YongLi YingWu HongZong Min-HuaSmith Thomas JChen Xin-De<p>Abstract</p> <p>Background</p> <p>The bacterium <it>Acetobacter</it> sp. CCTCC M209061 is a promising whole-cell biocatalyst with exclusive anti-Prelog stereoselectivity for the reduction of prochiral ketones that can be used to make valuable chiral alcohols such as (<it>R</it>)-4-(trimethylsilyl)-3-butyn-2-ol. Although it has promising catalytic properties, its stability and reusability are relatively poor compared to other biocatalysts. Hence, we explored various materials for immobilizing the active cells, in order to improve the operational stability of biocatalyst.</p> <p>Results</p> <p>It was found that Ca-alginate give the best immobilized biocatalyst, which was then coated with chitosan to further improve its mechanical strength and swelling-resistance properties. Conditions were optimized for formation of reusable immobilized beads which can be used for repeated batch asymmetric reduction of 4′-chloroacetophenone. The optimized immobilized biocatalyst was very promising, with a specific activity of 85% that of the free-cell biocatalyst (34.66 <it>μ</it>mol/min/g dw of cells for immobilized catalyst <it>vs</it> 40.54 <it>μ</it>mol/min/g for free cells in the asymmetric reduction of 4′-chloroacetophenone). The immobilized cells showed better thermal stability, pH stability, solvent tolerance and storability compared with free cells. After 25 cycles reaction, the immobilized beads still retained >50% catalytic activity, which was 3.5 times higher than degree of retention of activity by free cells reused in a similar way. The cells could be recultured in the beads to regain full activity and perform a further 25 cycles of the reduction reaction. The external mass transfer resistances were negligible as deduced from Damkohler modulus Da < <1, and internal mass transfer restriction affected the reduction action but was not the principal rate-controlling step according to effectiveness factors <it>η</it> < 1 and Thiele modulus 0.3<<it>∅</it> <1.</p> <p>Conclusions</p> <p>Ca-alginate coated with chitosan is a highly effective material for immobilization of <it>Acetobacter</it> sp. CCTCC M209061 cells for repeated use in the asymmetric reduction of ketones. Only a small cost in terms of the slightly lower catalytic activity compared to free cells could give highly practicable immobilized biocatalyst.</p>http://www.microbialcellfactories.com/content/11/1/119ImmobilizationAsymmetric reduction<it>Acetobacter</it> sp. CCTCC M209061Alginate-chitosanMass transfer |
| spellingShingle | Chen Xiao-Hong Wang Xiao-Ting Lou Wen-Yong Li Ying Wu Hong Zong Min-Hua Smith Thomas J Chen Xin-De Immobilization of <it>Acetobacter</it> sp. CCTCC M209061 for efficient asymmetric reduction of ketones and biocatalyst recycling Microbial Cell Factories Immobilization Asymmetric reduction <it>Acetobacter</it> sp. CCTCC M209061 Alginate-chitosan Mass transfer |
| title | Immobilization of <it>Acetobacter</it> sp. CCTCC M209061 for efficient asymmetric reduction of ketones and biocatalyst recycling |
| title_full | Immobilization of <it>Acetobacter</it> sp. CCTCC M209061 for efficient asymmetric reduction of ketones and biocatalyst recycling |
| title_fullStr | Immobilization of <it>Acetobacter</it> sp. CCTCC M209061 for efficient asymmetric reduction of ketones and biocatalyst recycling |
| title_full_unstemmed | Immobilization of <it>Acetobacter</it> sp. CCTCC M209061 for efficient asymmetric reduction of ketones and biocatalyst recycling |
| title_short | Immobilization of <it>Acetobacter</it> sp. CCTCC M209061 for efficient asymmetric reduction of ketones and biocatalyst recycling |
| title_sort | immobilization of it acetobacter it sp cctcc m209061 for efficient asymmetric reduction of ketones and biocatalyst recycling |
| topic | Immobilization Asymmetric reduction <it>Acetobacter</it> sp. CCTCC M209061 Alginate-chitosan Mass transfer |
| url | http://www.microbialcellfactories.com/content/11/1/119 |
| work_keys_str_mv | AT chenxiaohong immobilizationofitacetobacteritspcctccm209061forefficientasymmetricreductionofketonesandbiocatalystrecycling AT wangxiaoting immobilizationofitacetobacteritspcctccm209061forefficientasymmetricreductionofketonesandbiocatalystrecycling AT louwenyong immobilizationofitacetobacteritspcctccm209061forefficientasymmetricreductionofketonesandbiocatalystrecycling AT liying immobilizationofitacetobacteritspcctccm209061forefficientasymmetricreductionofketonesandbiocatalystrecycling AT wuhong immobilizationofitacetobacteritspcctccm209061forefficientasymmetricreductionofketonesandbiocatalystrecycling AT zongminhua immobilizationofitacetobacteritspcctccm209061forefficientasymmetricreductionofketonesandbiocatalystrecycling AT smiththomasj immobilizationofitacetobacteritspcctccm209061forefficientasymmetricreductionofketonesandbiocatalystrecycling AT chenxinde immobilizationofitacetobacteritspcctccm209061forefficientasymmetricreductionofketonesandbiocatalystrecycling |