title: Optimization of culture conditions to produce high yields of active Acetobacter sp. CCTCC M209061 cells for anti-Prelog reduction of prochiral ketones.
abstract: BACKGROUND
  Chiral alcohols are widely used in the synthesis of chiral pharmaceuticals, flavors and functional materials and appropriate whole-cell biocatalysts offer a highly enantioselective, minimally polluting route to these valuable compounds. The recently isolated strain Acetobacter sp. CCTCC M209061 showed exclusive anti-Prelog stereoselectivity for the reduction of prochiral ketones, but the low biomass has limited its commercialization and industrial applications. To tackle this problem, the effects of medium components and culture conditions on the strain's growth and reduction activity were explored.
  
  
  RESULTS
  By using a one-at-a-time method and a central composite rotatable design (CCRD), the optimal medium and culture conditions were found to be as follows: glucose 8.26 g/L, fructose 2.50 g/L, soy peptone 83.92 g/L, MnSO4·H2O 0.088 g/L, pH 5.70, 30°C and 10% (v/v) inoculum. Under the above-mentioned conditions, the biomass after 30 h cultivation reached 1.10 ± 0.03 g/L, which was 9.5-fold higher than that obtained with basic medium. Also, the reduction activity towards 4'-chloroacetophenone was markedly enhanced to 39.49 ± 0.96 μmol/min/g from 29.34 ± 0.65 μmol/min/g, with the product e.e. being above 99%. Comparable improvements were also seen with the enantioselective bioreduction of 4-(trimethylsilyl)-3-butyn-2-one to the key pharmaceutical precursor (R) - 4-(trimethylsilyl)-3-butyn-2-ol.
  
  
  CONCLUSIONS
  The biomass and reduction activity of Acetobacter sp. CCTCC M209061 can be greatly enhanced through the optimization strategy. This facilitates use of the strain in the anti-Prelog stereoselective reduction of prochiral ketones to enantiopure chiral alcohols as building blocks for many industries.
authors.affiliation: Lab of Applied Biocatalysis, South China University of Technology, Guangzhou, 510640, China.
authors.forename: Xiao-Hong
authors.initials: XH
authors.lastname: Chen
authors.forename: Wen-Yong
authors.initials: WY
authors.lastname: Lou
authors.forename: Min-Hua
authors.initials: MH
authors.lastname: Zong
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Smith
mesh_terms: D000091:Acetobacter / Q000254:growth & development* / Q000378:metabolism; D000438:Alcohols / Q000378:metabolism; D018533:Biomass; D018929:Cell Culture Techniques / Q000379:methods*; D002849:Chromatography, Gas; D003470:Culture Media / Q000737:chemistry*; D007659:Ketones / Q000378:metabolism*; D010084:Oxidation-Reduction
chemical_list: D000438:Alcohols; D003470:Culture Media; D007659:Ketones
references.citation: J Ind Microbiol Biotechnol. 2009 Dec;36(12):1513-27
references.pmid: 19784853
references.citation: Appl Microbiol Biotechnol. 2010 Jan;85(3):741-51
references.pmid: 19711069
references.citation: J Ind Microbiol Biotechnol. 2009 Jul;36(7):875-83
references.pmid: 19350297
references.citation: Bioresour Technol. 2008 Mar;99(5):1036-43
references.pmid: 17446065
references.citation: Bioresour Technol. 2009 Dec;100(23):5560-5
references.pmid: 19564106
references.citation: Appl Microbiol. 1964 Mar;12:165-8
references.pmid: 14133240
references.citation: Bioresour Technol. 2009 Sep;100(17):4012-6
references.pmid: 19356927
references.citation: Bioresour Technol. 2005 Jul;96(10):1175-82
references.pmid: 15683909
references.citation: FEMS Yeast Res. 2002 Dec;2(4):481-94
references.pmid: 12702265
references.citation: Appl Microbiol Biotechnol. 2005 Jan;66(4):352-5
references.pmid: 15538556
references.citation: Biochim Biophys Acta. 1969 May;180(1):63-7
references.pmid: 4306852
references.citation: Biotechnol Bioeng. 2007 Aug 15;97(6):1654-9
references.pmid: 17274067
references.citation: Bioelectrochemistry. 2009 Sep;76(1-2):53-62
references.pmid: 19329366
references.citation: BMC Biotechnol. 2009 Oct 22;9:90
references.pmid: 19849833
references.citation: Int J Food Microbiol. 2006 Apr 25;108(2):182-7
references.pmid: 16434117
references.citation: Int J Food Microbiol. 2010 Mar 31;138(1-2):130-6
references.pmid: 20117853