W. Su et al. / Tetrahedron: Asymmetry 15 (2004) 1275–1277
1277
panediol employed G. oxydans DSM 2003 under mild
conditions. The biotransformation occurred with high
retention times of the enantiomers were 7.151 min
-lactic acid) and 9.105 min ( -lactic acid). The abso-
(
L
D
molar conversion (98% of
D
-(ꢀ)-1,2-propanediol) and
lute configuration of the obtained acid was determined
by the comparison of the specific rotation of authentic
samples of the enantiomerically pure compounds. The
high enantioselectivity (ee 100%) when the substrate
concentration was lower than 20 g/L. When the sub-
strate concentration was higher, a decrease in pH in the
oxidation reaction was shown to influence the enantio-
selectivity. The maintenance of pH improved the selec-
tivity (ee from 80% to 100%). As a result, we have shown
20
specific rotational value of the product is ½aꢁ ¼ ꢀ1:8
D
(c 8, H2O). The stereochemical outcomes of the bio-
transformations were expressed as enantiomeric excesses
(ee’s) of the major enantiomer.
an approach for
technically and economically interesting.
D
-(ꢀ)-lactic acid production that is
Acknowledgements
4. Experimental
The financial support for the scientific research from the
Doctorial
(20020251004) and the National Key Program for Basic
Research (2002CCA400) and the Key Disciplinary
Foundation of Shanghai are fully acknowledged.
Foundation
of
Chinese
University
4.1. Microorganism, growth and biotransformation con-
ditions
The G. oxydans DSM 2003 strains were from our own
collection. For the highest growth of organism, several
media were tested with the best being chosen: Y-S
medium (pH 6.0), consisted of 8 g of sorbitol, 2.4 g of
yeast extract and other factors. The organisms were
incubated at 28 °C with shaking at 250 rpm for 24 h. The
cultivated cells were collected by centrifugation at
8000 rpm for 8 min. The cells were washed twice with
distilled water and then dried at 110 °C for 24 h for
determining the dry weight. Biotransformations were
directly carried out with growing cells or with cells
centrifuged and suspended in phosphate buffers (0.1 M)
at various pH values. Different concentrations of sub-
strates were added directly to the suspensions and flasks
shaken at 250 rpm and incubated at 28 °C, which were
the optimal conditions based on a previous report of
biotransformations using Gluconobacter strains.
References and notes
1. Sue, M.; Brian, M.; Linda, M. H. Crit. Rev. Biotechnol.
2001, 21, 1.
2. Deppenmeier, U.; Hoffmeister, M.; Prust, C. Appl. Micro-
biol. Biotechnol. 2002, 60, 233.
3. Arun, G.; Vinay, K. S.; Qazi, G. N.; Anil, K. J. Mol.
Microbiol. Biotechnol. 2001, 3, 445.
4. Romano, A.; Gandolfi, R.; Nitti, P.; Rollini, M.; Molinari,
F. J. Mol. Catal. B: Enzym. 2002, 17, 235.
5. Suzuki, T.; Kasai, N.; Minamimura, N. Microbial pro-
duction of optically active 1,2-diols using resting cells of
alcaligenes sp. DS-S-7G. J. Ferment. Bioeng. 1994, 78,
194.
6. Jongejan, A.; Machado, S. S.; Jongejan, J. A. J. Mol.
Catal. B: Enzym. 2000, 8, 121.
7. Schumacher, K.; Asche, S.; Heil, M.; Mosandl, A.; Engel-
Kristen, K.; Rauhut, D. Z Lebensm Unters Forsch A 1998,
207, 74.
8. Molinari, F.; Villa, R.; Aragozzini, F.; Leon, R.; Prazeres,
D. M. F. Tetrahedron: Asymmetry 1999, 10, 3003.
9. Demirci, A.; Pometto, A. L. J. Ind. Microbiol. Biotechnol.
1992, 11, 23.
10. Shieh, W. R.; Gopalan, A. S.; Sih, C. J. J. Am. Chem. Soc.
1985, 12, 2993.
11. Chen, C. S.; Zhou, B. N.; Girdaukas, G.; Shieh, W. R.;
Van Middlesworth, F.; Gopalan, A. S.; Sih, C. J. Bioorg.
Chem. 1984, 12, 98.
12. Gandolfi, R.; Borrometi, A.; Romano, A.; Gago, J. V. S.;
Molinari, F. Tetrahedron: Asymmetry 2002, 13, 2345.
4.2. Analytical methods
The production of lactic acid was routinely determined
by HPLC analysis using a ZORBAX SB-AQ column
(Agilent Technologies, USA) and an aqueous acidic
solution (H3PO4, 1%) as the eluent in 1 mL/min. Sam-
ples were taken at intervals, brought to pH 1.0 by the
addition of HCl (1 M) and extracted with an equal
volume of CHCl3. The enantiomeric composition was
also determined by HPLC analysis using an SU-
MICHIRAL OA-5000 column (Sumika Chemical
Analysis, Japan) and the eluent composed with 2 mM
copper sulfate in water/2-propanol (95/5, v/v). The