An easy and efficient method for the production of carboxylic acids and aldehydes by microbial oxidation of primary alcohols

Article abstract of DOI:10.1016/S0040-4039(00)02008-6

An easy and efficient methodology for obtaining aldehydes or carboxylic acids by oxidation of the corresponding primary alcohols with acetic acid bacteria is reported. When the biotransformation is performed in water the acids are obtained; aldehydes can be accumulated by using a water/isooctane two-liquid phase system.

Full text of DOI:10.1016/S0040-4039(00)02008-6

TETRAHEDRON
LETTERS
Pergamon
Tetrahedron Letters 42 (2001) 513–514
An easy and efficient method for the production of carboxylic
acids and aldehydes by microbial oxidation of primary alcohols
Raffaella Gandolfi, Nicola Ferrara and Francesco Molinari*
Dipartimento di Scienze e Tecnologie Alimentari e Microbiologiche, Sezione Microbiologia Industriale,
Universita` degli Studi di Milano, via Celoria 2, 20133 Milan, Italy
Received 2 October 2000; revised 1 November 2000; accepted 8 November 2000
Abstract—An easy and efficient methodology for obtaining aldehydes or carboxylic acids by oxidation of the corresponding
primary alcohols with acetic acid bacteria is reported. When the biotransformation is performed in water the acids are obtained;
aldehydes can be accumulated by using a water/isooctane two-liquid phase system. © 2001 Elsevier Science Ltd. All rights
reserved.
Biotransformations are a useful and complementary
tool for preparative organic chemistry. In the course of
a biotransformation the chemo-, regio- and stereoselec-
tive transformation of a substrate often takes place
under mild and ecologically-compatible conditions. The
oxidation of primary alcohols by acetic acid bacteria to
the respective acids is a widespread transformation
which proceeds firstly through the action of alcohol
dehydrogenases and secondly through aldehyde dehy-
drogenase.1 The overall dehydrogenase activities are
generally not very specific and aldehydes are not nor-
mally accumulated.2–4 The use of two-liquid phase
systems (composed of water and an organic solvent)
may provide a method for the production of sufficiently
hydrophobic aldehydes, since they can be extracted in
situ from the aqueous phase, avoiding further oxida-
tion.5 Two strains of acetic acid bacteria were used in
this work: Acetobacter sp. ALEG MIM, which has
previously shown the highest yields of phenylacetalde-
hyde production5 and Gluconobacter asaii MIM 1000/
14.6 The oxidation of different alcohols was carried out
in water and in a two-liquid phase system composed of
water and isooctane (vol/vol 1/1) (Scheme 1).7
which proceeds through the action of two dehydroge-
nases is not very specific and, therefore, aldehydes are
not accumulated. Acetobacter sp. ALEG oxidized all
the substrates with high rates and yields, the only
exception being benzyl alcohol; also the Gluconobacter
showed good selectivities, although sometimes (1d and
1h) with lower yields.
The transformations carried out in the two-liquid phase
system composed of water and isooctane (vol/vol 1/1)
showed that the use of an apolar extractive solvent
allowed the accumulation of the aldehydes which are
mostly found in the organic phase. Over prolonged
reaction times the aldehydes were further oxidized to
carboxylic acids, with the exception of geranial which
was not further transformed by Acetobacter sp. ALEG.
With Gluconobacter asaii we observed a higher conver-
sion of geraniol in the two-liquid phase system than in
water; this may be due to an inhibitory effect of geran-
iol on the microbial dehydrogenases, which is reduced
As shown in Table 1, the oxidation of primary alcohols
in water by the two strains tested furnished the respec-
tive carboxylic acids as main products, while aldehydes
were only transiently observed. The transformation
Keywords: biotransformation; carboxylic acid; aldehyde; alcohol oxi-
dation; acetic acid bacteria; two-liquid phase system.
* Corresponding author. Tel.: 0039-0223955844; fax: 0039-
0270630829; e-mail: francesco.molinari@unimi.it
Scheme 1.
0040-4039/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved.
PII: S0040-4039(00)02008-6

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R. Gandolfi et al. / Tetrahedron Letters 42 (2001) 513–514
Table 1.
Acetobacter
Gluconobacter
Water
Yielda
Water/isooctane
Water
Yield
Water/isooctane
Substrate Product
Time (h) Product
Yieldb
Time (h) Product
Time (h) Product
Yield
Time (h)
1a
1b
1c
1d
1e
1f
1g
1h
1i
3a
3b
3c
3d
3e
3f
3g
3h
3i
\97
\97
\97
\97
25
\97
\97
\97
40
3
3
3
24
24
3
2
8
24
2a
2b
2c
2d
2e
2f
2g
2h
2i
74
90
87
72
B5
90
93
77
B5
1
1
1
4
3a
3b
3c
3d
3e
3f
3g
3h
3i
\97
\97
\97
16
B5
\97
\97
20
4
4
3
24
24
5
5
24
24
2a
2b
2c
2d
2e
2f
2g
2h
2i
93
90
91
29
B5
85
96
24
B5
45 min
1
45 min
5
24
2
1
4
24
45 min
45 min
45 min
24
33
24
a Yields (%) determined by standard GLC analysis; carboxylic acids were analysed after conversion to the corresponding methyl ester after
treatment with CH2N2.
b The yields of the aldehydes are related to the sum of the products detected in the aqueous and organic phase.
beni, M. J. Chem. Technol. Biotechnol. 1997, 70/3, 294–
298.
5. Molinari, F.; Gandolfi, R.; Aragozzini, F.; Le`on, R.;
Prazeres, D. M. F. Enzyme Microb. Technol. 1999, 25,
729–735.
in the presence of an organic phase where the hydro-
phobic substrate mostly accumulates. The aldehydes
produced by these biotransformations were easily
purified from the organic phase.8
6. Strains (Acetobacter sp. ALEG and Gluconobacter asaii
1000/14) were from our collection (MIM, Microbiologia
Industriale Milano) and routinely maintained on GYC
The racemic mixture of 1i was subjected to a kinetic
resolution, furnishing the (S)-alcohol with high ee.
(95% at 40% molar conversion); the use of acetic acid
bacteria to perform enantioselective oxidation of
racemic mixtures of primary alcohols has been already
reported.9–11 The enantiomeric composition of 2-
phenylpropanoic acid was determined as previously
described.11
solid medium (glucose 50 g l−1, yeast extract 10 g l−1
,
CaCO3 30 g l−1, agar 15 g l−1, pH 6.3) at 28°C. Sub-
merged cultures were carried out in a GlyY medium
(glycerol 25 g l−1, yeast extract 10 g l−1, pH 5) into 1 l
Erlenmeyer flasks containing 200 ml of medium on a
reciprocal shaker (100 spm).
7. Experiments were carried out with 24 hour submerged
cultures. In experiments with two-liquid phase systems,
solvents were added to reach the desired volumes. Neat
substrates (2.5 g l−1) were directly added to the suspen-
sions and flasks were shaken on a reciprocal shaker (100
spm).
8. The work-up of the production of phenylthioacetalde-
hyde is reported as an example. Biotransformation was
carried out starting from 500 mg of the alcohol in 200 ml
of cultural broth containing 200 ml of isooctane and after
50 minutes the reaction mixture was centrifuged (15000 g,
10 min) to remove the bacterial cells, the surnatant was
extracted with ethyl acetate. The organic extracts were
dried over Na2SO4 and the solvent removed; the crude
product was purified by flash chromatography (hexane/
ethyl acetate, 7/3) to give 415 mg of phenylthioacetalde-
The use of a two-liquid phase system composed of
water and isooctane appears, therefore, to be suited to
the production of various aldehydes by oxidation of
primary alcohols using acetic acid bacteria. This micro-
bial biotransformation seems a promising and possibly
general method to furnish aldehydes under mild and
ecologically compatible conditions.
Acknowledgements
This work was supported by the C.N.R. Target Project
on Biotechnology (n 97.01019. PF 115.08601). The
authors would like to thank Dr. Angela Bassoli for
valuable help and GC/MS analysis of the products.
hyde. All compounds were characterized by
a
combination of 1H NMR, GC/MS and molar conver-
sions determined by GC or reversed phase HPLC analy-
sis.
References
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