Biotechnology Letters 25: 887–890, 2003.
© 2003 Kluwer Academic Publishers. Printed in the Netherlands.
887
Application of a two-stage temperature control strategy for enhanced
glutathione production in the batch fermentation by Candida utilis
Gongyuan Wei
1
,YinLi
1,2
, Guocheng Du
1
&JianChen
1,2,∗
1
Key Laboratory of Industrial Biotechnology, Ministry of Education and
2
Laboratory of Environmental Biotech-
nology, School of Biotechnology, Southern Yangtze University, Wuxi 214036, P.R. China
∗
Author for correspondence (Fax: +86-510-5888301; E-mail: jchen@sytu.edu.cn)
Received 18 December 2002; Revisions requested 2 January 2003/4 March 2003; Revisions received 3 March 2003/28 March 2003; Accepted
7 April 2003
Key words: batch fermentation, Candida utilis, glutathione, temperature, two-stage strategy
Abstract
In batch culture for glutathione production with Candida utilis, a higher temperature (30
◦
C) was required to hasten
cell growth while a lower temperature (26
◦
C) was needed to increase the production of glutathione. A two-stage
temperature control strategy was used to enhance both the yield and the productivity of glutathione. As a result,
glutathione production was increased by 5% and 23% of that at 26
◦
C and 30
◦
C, respectively, and the intracellular
glutathione content reached 2.5% (w/w).
Introduction
Glutathione (
L
-γ -glutamyl-
L
-cysteinylglycine) is
widely distributed in nature and protects cells against
oxidation (Meister 1994). Its antioxidation function is
closely associated with its role in maintaining the nor-
mal redox environment of cells (Izawa et al. 1995).
Glutathione is now widely used in medicine, food and
the cosmetic industry. The commercial demand for it
has been expanding.
Temperature is one of the important environmental
factors in the production of glutathione by fermenta-
tion. According to a previous study (Tadayuki et al.
1985), cell growth, glutathione formation and intra-
cellular glutathione content were all influenced by
temperature. In general, the optimal temperatures for
cell growth and glutathione production are different
(Mei et al. 2000). Many researchers have tried to im-
prove the microbial production of glutathione (Murata
et al. 1980, Shimizu et al. 1991, Alfafara et al. 1992,
Li et al. 1998) but very little work has been done to
investigate the influence of temperature on glutathione
production with yeasts. In this paper, the effects of
temperature on the batch fermentation of glutathione
with Candida utilis were studied in detail. Also, an
optimal two-stage temperature control strategy was
developed to improve the yield and the productivity
of glutathione in the batch fermentation.
Materials and methods
Microorganism and growth
Candida utilis WSH 02-08 was grown on a medium of
20gglucosel
−1
,20gpeptonel
−1
, 10 g yeast extract
l
−1
,pH6at30
◦
C for 20 h on a reciprocal shaker
at 200 rev min
−1
, which was then inoculated at 10%
(v/v) into a 7 l stirred fermenter. The fermentation
medium contained 30 g glucose l
−1
, 8 g ammonium
sulfate l
−1
,3gKH
2
PO
4
l
−1
and 0.25 g MgSO
4
l
−1
.
pH was controlled automatically at 5.5 by adding 3 M
H
2
SO
4
or 3 M NaOH. The aeration rate was 5 l min
−1
and the agitation rate was controlled at 300 rev min
−1
.
Analytical methods
Culture broth of 25 ml was centrifuged at 2000 × g
for 10 min and the cells washed twice with distilled
water. Dry cell weight (DCW) was determined af-
ter drying the cells at 105
◦
C to a constant weight.