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Efficient synthesis of hydroxytyrosol from LDOPA using engineered Escherichia coli whole cells Chaozhi Li, Pu Jia, Yajun Bai, Tai-Ping Fan, Xiaohui Zheng, and yujie cai J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.9b01856 • Publication Date (Web): 28 May 2019 Downloaded from http://pubs.acs.org on May 31, 2019
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Journal of Agricultural and Food Chemistry
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Efficient synthesis of hydroxytyrosol from L-DOPA using
2
engineered Escherichia coli whole cells
3
Chaozhi Lia, Pu Jiab, Yajun Baib, Tai-ping Fanc, Xiaohui Zhengb*, Yujie Caia*
4
a
5
Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
6
b
College of Life Sciences, Northwest University, Xi’an, Shaanxi 710069, China
7
c
Department of Pharmacology, University of Cambridge, Cambridge CB2 1T, UK
The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of
8 9
First author: Chaozhi Li and Pu Jia contributed equally to this work
10
a*
11
The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of
12
Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
13
Tel.: +86-18961727911
14
Fax: +86-0551-85327725
15
E-mail:
[email protected] 16
Address: Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
17
b*
18
E-mail:
[email protected] 19
Address: College of Life Sciences, Northwest University, Xi’an, Shaanxi 710069,
20
China
Corresponding authors: Yujie Cai
Xiaohui Zheng
21
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Abstract
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Hydroxytyrosol is a high value-added compound with a variety of biological and
24
pharmacological activities. In this study, a whole-cell catalytic method for the synthesis
25
of hydroxytyrosol was developed: aromatic amino acid aminotransferase (TyrB), L-
26
glutamate dehydrogenase (GDH), α-keto acid decarboxylase (PmKDC), and aldehyde
27
reductase (YahK) were co-expressed in Escherichia coli to catalyze the synthesis of
28
hydroxytyrosol from L-DOPA. The plasmids with different copy numbers were used
29
to balance the expression of the four enzymes, and the most appropriate strains (pRSF-
30
yahK-tyrB, pCDF-gdh-Pmkdc) were identified. After determining the optimum
31
temperature (35 ℃) and pH (7.5) for whole-cell catalysis, the yield of hydroxytyrosol
32
reached 36.33 mM (5.59 g/L) and the space-time yield reached 0.70 g L−1 h−1.
33 34
Key words:
35
L-DOPA, hydroxytyrosol, Escherichia coli, whole-cell catalysis, co-expression
36 37 38 39 40 41 42
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Introduction
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Hydroxytyrosol (3, 4-dihydroxyphenylethanol) is a natural polyphenolic
45
compound, which has high fat- and water-solubility. It is an excellent antioxidant with
46
many biological and pharmacological activities, such as anticancer, antibacterial, and
47
anti-inflammatory properties 1-4, so it is a promising compound for the pharmaceutical
48
industry 5. Hydroxytyrosol mainly exists in olives in the form of oleuropein, hence
49
hydroxytyrosol can be extracted from olives or the wastewater from olive processing
50
6-8,
51
but the source of raw materials is limited and the yield is low. Several methods of chemical synthesis have been developed. The starting
52
materials,
53
dihydroxybenzaldehyde
54
converted to hydroxytyrosol by one or more steps in the presence of a chemical catalyst.
55
However, there are problems with many of these methods, such as an expensive
56
substrate, harsh conditions, complicated steps, or low yield, so that they are not suitable
57
for large-scale industrial production.
58
such
as
3,4-dihydroxyphenylacetic 11,
tyrosol
12-14,
acid
9,
catechol10,
and 3,4-dimethoxyphenylacetic acid
3,415,
are
Some biosynthesis methods have also been reported. For example, Espin et al.
59
used mushroom tyrosinase to convert tyrosol into hydroxytyrosol
60
Serratia marcescens
61
can
62
Pseudomonas mendocina KR1 can convert 2-phenylethanol into hydroxytyrosol
63
Orenes-Piñero et al. transferred the phenol hydroxylase gene from Geobacillus
convert
17,
tyrosol
Pseudomonas aeruginosa into
hydroxytyrosol.
18,
16.
In addition,
and Pseudomonas putida F6
Toluene-4-monooxygenase
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from 20.
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thermoglucosidasius into Escherichia coli, to transform tyrosol into hydroxytyrosol 21.
65
Satoh et al. cloned tyrosine hydroxylase from mouse into E. coli to convert tyrosine to
66
hydroxytyrosol 22. Li et al. designed an artificial pathway to obtain hydroxytyrosol from
67
simple carbon sources, such as glucose and glycerol, through a series of steps 23. Wei
68
et al. designed multiple-pathway networks to synthesize hydroxytyrosol from tyrosine
69
based on HpaBC mutants 24. However, the efficiency of these methods is not high or
70
the substrate is expensive. The task to find methods for the production of
71
hydroxytyrosol that are economical, simple, and efficient is still challenging.
72
In this study, a pathway for the production of hydroxytyrosol from L-DOPA, using
73
engineered E. coli whole cells is proposed. Aromatic amino acid aminotransferase
74
(TyrB), L-glutamate dehydrogenase (GDH), α-keto acid decarboxylase (PmKDC), and
75
aldehyde reductase (YahK) were co-expressed in E. coli. First, L-DOPA is converted
76
to 3,4-dihydroxyphenylpyruvic acid through the transamination of TyrB, which is
77
further converted to 3,4-dihydroxyphenylacetaldehyde by decarboxylation of PmKDC,
78
and finally, 3, 4-dihydroxyphenylacetaldehyde is reduced by YahK to hydroxytyrosol.
79
The transamination and the reduction were coupled by GDH to achieve cofactor
80
regeneration (Fig. 1).
81
Materials and methods
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Strains, plasmids, and reagents
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The bacterial strains and plasmids used in this study were listed in Table 1. E. coli
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JM109 and E. coli BL21 (DE3), both from TaKaRa (Dalian, China), were used as 4 ACS Paragon Plus Environment
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cloning host and expression host, respectively. The pRSFDuet-1, pETDuet-1, and
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pCDFDuet-1 expression vectors were all from Novagen (Darmstadt, Germany).
87
Molecular biological reagents such as T4 DNA ligase, PrimeSTAR HS DNA
88
polymerase, restriction endonuclease, Taq DNA polymerase, plasmid miniprep kit, and
89
DNA gel extraction kit were from TaKaRa. Isopropyl β-D-1-thiogalactopyranoside
90
(IPTG), ampicillin, streptomycin, and kanamycin were from Sangon Biotech (Shanghai,
91
China). L-DOPA and hydroxytyrosol were from Sigma-Aldrich (St. Louis, MO, USA).
92
Other chemical reagents are analytically pure and of an analytical grade.
93
Pathway and plasmid construction
94
The synthesis pathway of hydroxytyrosol constructed in this study is shown in Fig.
95
1. The gdh gene from Clostridium difficile ATCC 9689 (GenBank ID: M65250)25 was
96
synthesized by Sangon Biotech. The tyrB, Pmkdc, yahK were cloned from E. coli BL21
97
(DE3) (GenBank ID: ACT45717)26, Proteus mirabilis JN458 (GenBank ID:
98
KY441412)27 and E. coli BL21 (DE3) (GenBank ID: AAC73428.1)28, respectively. The
99
genes were amplified by PCR and three plasmids (pRSFDuet-1, pETDuet-1,
100
pCDFDuet-1) used in this study were extracted by the plasmid miniprep kit (TaKaRa).
101
The plasmids and genes were digested, and then the genes were ligated to the plasmids
102
with T4 DNA ligase. The recombinant plasmids were transformed into E. coli JM109
103
and verified by colony PCR and sequencing. All successfully constructed plasmids
104
were transformed into E. coli BL21 (DE3) to express the genes. The plasmids and
105
strains constructed in this study are shown in Table 1. 5 ACS Paragon Plus Environment
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Growth media, culture conditions, and preparation of whole-cell catalysts
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The constructed strains were inoculated into a test tube containing 3 mL Luria-
108
Bertani (LB) medium and cultured for 12 h, and then a 250-mL Erlenmeyer flask
109
containing 50 mL LB medium was inoculated with 1 mL of culture and incubated at 37
110
℃, 200 rpm. When the optical density (OD) at 600 nm reached 0.6, IPTG was added to
111
a final concentration of 0.4 mM, and cultured at 15 ℃, 200 rpm for 24 h. Corresponding
112
antibiotics were added at the appropriate working concentration throughout the culture
113
process. The bacteria were collected by centrifugation (8000×g, 10 min), washed with
114
pH 6.0 phosphate buffer (PB) and resuspended to obtain the whole-cell catalyst, which
115
was stored at 4 ℃.
116
Whole-cell catalysis and optimization of reaction conditions
117
The reaction system was 6 mL of PB containing whole-cell catalysts 20 g/L (wet
118
cells), L-DOPA 40.61 mM, L-glutamate 30 mM, and NAD+ 30 mM. The reaction was
119
carried out in a 50-mL Erlenmeyer flask at 30 ℃, 100 rpm for 6 h and terminated by
120
boiling in a water bath for 2 min. In order to optimize the reaction conditions, different
121
temperatures and pHs were set to explore the optimum temperature and pH of the
122
whole-cell catalyst.
123
Enzyme activity assays
124
The activity of TyrB was assayed by detecting the increase of hydroxytyrosol
125
when excess GDH, PmKDC, YahK, and L-DOPA were added. Excess L-glutamate and
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NAD+ were added when assaying the activity of GDH and then the increase of NADH 6 ACS Paragon Plus Environment
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was measured at 340 nm (Shimadzu UV-1800, Suzhou, China). The enzyme activity of
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PmKDC was determined by adding excess 3,4-dihydroxyphenylpyruvic acid, NADH,
129
and YahK, and detecting the increase in hydroxytyrosol concentration. In determining
130
the activity of yahK, excess 3,4-dihydroxyphenylpyruvic acid, NADH, and PmKDC
131
were added to detect the increase in hydroxytyrosol concentration. One unit of enzyme
132
activity (U) was defined as the amount of enzyme required for the increase of 1μmol
133
hydroxytyrosol (NADH) per min. The results were converted to units of enzyme
134
activity contained in 1 mL of the whole-cell catalyst. All assays were repeated three
135
times.
136
Analytical methods
137
Ultra-performance liquid chromatography-mass spectrometry (UPLC-MS, Waters
138
Acquity UPLC and Waters MALDI SYNAPT Q-TOF MS, Milford, USA) was used to
139
confirm the formation of hydroxytyrosol. The amount of hydroxytyrosol was
140
determined by high-performance liquid chromatography (HPLC, PerkinElmer Flexar,
141
Waltham, USA). The analytical conditions of HPLC were as follows: PerkinElmer
142
Series 200 UV/VIS detector, Waters SunFire C18 column (5 μm, 4.6 × 250 mm);
143
column temperature 35 ℃, detection wavelength 280 nm, injection quantity 10 μL, flow
144
rate 1 mL/min. The mobile phase A was 100% acetonitrile and the mobile phase B was
145
water containing 0.1% formic acid. The mobile phase was changed from A/B=10/90 to
146
A/B=100/0 for 15 min, and a linear gradient was performed.
147
Results 7 ACS Paragon Plus Environment
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Confirmation of hydroxytyrosol
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The whole-cell catalytic reaction was carried out with strain 1 and the reaction
150
solution was assayed by UPLC-MS with Electron Spray Ionization (ESI) under
151
negative ion mode. [M-H]- appeared at m/z=153, in accordance with the molecular
152
weight of hydroxytyrosol and the results of the standard, which indicated that the
153
synergistic effect of the four enzymes produced hydroxytyrosol (Fig. 2). From the
154
results of the UPLC-MS assay, we also know that hydroxytyrosol has a strong
155
absorption under UV light at 280 nm, which influenced the detection conditions for the
156
detection of hydroxytyrosol by HPLC in subsequent experiments.
157
Comparison of the ability of different strains to produce hydroxytyrosol
158
Plasmids with different copy numbers have previously been used to balance the
159
expression of enzymes in a multi-enzyme system 29-30. To achieve the best performance
160
for the present pathway, we used three plasmids with different copy numbers:
161
pRSFDuet-1, pETDuet-1, and pCDFDuet-1. A series of strains were constructed (Table
162
1), and their production capacity and enzyme activity were compared (Fig. 3, Fig. 4).
163
Firstly, strains 1–4 were constructed. Under the premise that the overexpression of
164
yahK was strong, gdh, tyrB, and Pmkdc were strongly overexpressed (strains 2, 3, and
165
4). In strains 1–4, the enzyme activity of TyrB and the amount of hydroxytyrosol
166
increased significantly when tyrB was strongly overexpressed but the amount of
167
hydroxytyrosol did not change significantly after the activities of GDH and PmKDC
168
increased. Therefore, it was determined that TyrB was the bottleneck for this pathway, 8 ACS Paragon Plus Environment
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and the enzyme activities of GDH and PmKDC are relatively sufficient. In addition,
170
strain 5 (tyrB, Pmkdc, gdh were strongly overexpressed but yahK was modestly
171
overexpressed in comparison), strain 6 (yahK and tyrB were strongly overexpressed,
172
gdh and Pmkdc were modestly overexpressed in comparison) and strain 7 (all genes
173
were strongly overexpressed) were constructed. Compared with strain 7, the amount of
174
hydroxytyrosol in strain 5 decreased significantly after the overexpression of yahK was
175
reduced, which indicated that strong overexpression of yahK was also essential. Finally,
176
strains 3, 6, and 7, which exhibited high yields, were compared and strain 3 was
177
determined to be the best strain for the production of hydroxytyrosol, with a yield that
178
reached 24.31 mM (3.74 g/L). Subsequently, we used sodium dodecyl sulfate-
179
polyacrylamide gel electrophoresis (SDS-PAGE) to verify the expression of the four
180
enzymes in strain 3 (Fig. 5). Because the molecular weights of TyrB, GDH, and YahK
181
are similar, they are difficult to distinguish well in SDS-PAGE, hence, their expression
182
is mainly verified by enzyme activity assays.
183
Optimization of pH and temperature of whole-cell catalysis
184
In order to improve the production of hydroxytyrosol, the optimum pH and
185
temperature of whole-cell catalysis were determined in strain 3. Hydroxytyrosol was
186
synthesized at different pHs (5–9), and the yield reached the highest when pH was 7.5
187
(Fig. 6a). Moreover, hydroxytyrosol was synthesized at temperatures of 20 ℃, 25 ℃,
188
30 ℃, 35 ℃, 40 ℃, and 45 ℃. The optimum temperature was found to be 35 ℃ (Fig.
189
6b). To sum up, the optimum conditions for the synthesis of hydroxytyrosol in strain 3 9 ACS Paragon Plus Environment
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are pH 7.5 and 35 ℃.
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Production of hydroxytyrosol under optimal conditions
192
Based on the above studies, strain 3 was used to catalyze the synthesis of
193
hydroxytyrosol under the optimum conditions, and the time course of the synthesis of
194
hydroxytyrosol was studied (Fig. 7). Considering that a high substrate concentration is
195
beneficial to the improvement of volumetric productivity and process economy, but that
196
the solubility of L-DOPA in water is only about 3 g/L (15.23 mM), we used
197
supersaturated L-DOPA (8 g/L). Therefore, before the supply of undissolved L-DOPA
198
was exhausted, its concentration was almost unchanged. When all the L-DOPA was
199
dissolved, its concentration decreased gradually, and the concentration of
200
hydroxytyrosol increased gradually with the progress of the reaction. After 8 h, L-
201
DOPA was almost exhausted and the concentration of hydroxytyrosol reached the
202
maximum value. Ultimately, up to 36.33 mM hydroxytyrosol (5.59 g/L) was obtained
203
from 40.61 mM L-DOPA (8 g/L), and the space-time yield was up to 0.70 g L−1 h−1.
204
Discussion
205
Whole-cell biocatalysis has been widely used in the synthesis of many compounds
206
31-36. Firstly, the whole-cell catalyst has better operability and economy than the isolated
207
enzyme 31; secondly, the whole-cell catalyst has better stability and can be reused in
208
several bioconversions with little loss in activity 34; finally, the tolerance of the whole-
209
cell catalyst to substrate and product was higher than that of the free-enzyme system 35.
210
These characteristics suggest that the whole-cell catalyst is more suitable for industrial 10 ACS Paragon Plus Environment
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processes than the free-enzyme system. In addition, the growth stage of the bacterial
212
strain is not suitable for synthesis of hydroxytyrosol because of its extensive
213
antibacterial activity 37. The whole-cell catalysis can separate the growth stage of the
214
strain from the synthesis stage of hydroxytyrosol, avoiding the inhibition of
215
hydroxytyrosol on the growth of the strain.
216
Here, we designed a pathway to synthesize hydroxytyrosol from L-DOPA through
217
three steps: transamination, decarboxylation, and reduction (Fig. 1). On the one hand,
218
α-ketoglutaric acid is consumed as an amino receptor in the transamination, and L-
219
glutamate is produced at the same time. On the other hand, NADH is consumed as the
220
reduction equivalent in the reduction, and NAD+ is produced at the same time.
221
Therefore, we used L-glutamate dehydrogenase to couple the transamination and
222
reduction, achieving the regeneration of both α-ketoglutaric acid and NADH. Usually,
223
the regeneration of NADH uses glucose dehydrogenase or formate dehydrogenase
224
39.
225
impurity (gluconic acid) into the reaction system, which leads to an increase in the
226
complexity of product purification. Formate dehydrogenase does not produce new
227
impurities, but its activity and stability are not high. In this pathway, the use of
228
transaminase instead of deaminase or amino acid oxidase makes the synthesis of
229
hydroxytyrosol do not need oxygen, which is conducive to prevent hydroxytyrosol from
230
being oxidized.
231
38-
Glucose dehydrogenase has high activity and stability. However, it introduces a new
In the multi-enzyme cascade reaction, if the activity of each enzyme cannot be 11 ACS Paragon Plus Environment
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well coordinated, bottleneck or excess enzyme activity will appear, which will usually
233
lead to the accumulation of metabolic intermediates and affect the production of the
234
final product. Therefore, it is necessary to take measures to balance the expression of
235
the enzymes in this study. One way to balance the expression of enzymes is to use
236
plasmids with different copy numbers 29-30. In this study, tyrB and yahK were strongly
237
overexpressed in pRSFDuet-1 (high copy number), while gdh and Pmkdc with
238
sufficient activity were weakly overexpressed in pCDFDuet-1 (low copy number),
239
which made the whole synthesis pathway achieve the highest performance (strain 3).
240
Interestingly, the production of strain 6 (pRSF-yahK-tyrB, pET-gdh-Pmkdc) and strain
241
7 (pRSF-tyrB-gdh-Pmkdc-yahK) was slightly lower than that of strain 3 (Fig. 3). This
242
phenomenon may be as a result of strong overexpression of too many enzymes, leading
243
to a heavy metabolic burden on the strain 40, which in turn affected the expression of
244
rate-limiting enzymes. In strain 3, the enzyme with excess activity was weakly
245
overexpressed, with only the rate-limiting enzyme being strongly overexpressed, so that
246
more intracellular resources and energy would be given to the rate-limiting enzyme.
247
After the optimization of pH and temperature of the whole-cell catalysis, strain 3
248
synthesized 36.33 mM hydroxytyrosol (5.59 g/L) from 40.61 mM L-DOPA within 8 h,
249
and the space-time yield was up to 0.70 g L−1 h−1, characteristics which were
250
significantly better than those reported in previous studies(Table 2). However, there are
251
some endogenous enzymes in E. coli that degrade phenolic compounds, for example,
252
HpaD (3, 4-dihydroxyphenylacetic acid 2, 3-dioxygenase) and MhpB (2,312 ACS Paragon Plus Environment
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dihydroxyphenlypropionic acid 1, 2-dioxygenase) can destroy the catechol structure of
254
phenolic compounds and cause their ring opening41, FeaB (phenylacetaldehyde
255
dehydrogenase)
256
dihydroxyphenylacetic acid23, so that L-DOPA, 3, 4-dihydroxyphenylpyruvic acid, 3,
257
4-dihydroxyacetaldehyde and hydroxytyrosol are likely to be degraded. Therefore, if
258
these endogenous enzymes are knocked out, a better result may be obtained.
may
oxidize
3,
4-dihydroxyphenylacetaldehyde
to
3,
4-
259
In conclusion, hydroxytyrosol was synthesized efficiently from L-DOPA by the
260
catalysis of engineered E. coli co-expressing aromatic amino acid aminotransferase, L-
261
glutamate dehydrogenase, α-keto acid decarboxylase, and aldehyde reductase. At the
262
same time, cofactor regeneration was achieved. At present, there are many methods to
263
produce L-DOPA 50, which is easy to obtain commercially and is cheap relative to the
264
high value of hydroxytyrosol. As far as we know, this is the first whole-cell catalytic
265
synthesis of hydroxytyrosol from L-DOPA. This method has the advantages of simple
266
operation, high efficiency, and good economy, and has great potential for industrial
267
application.
268
Abbreviations GDH
L-glutamate dehydrogenase
IPTG
isopropyl β-D-1-thiogalactopyranoside
PB
phosphate buffer
UPLC-MS
ultra-performance liquid chromatography-mass spectrometry
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HPLC
high-performance liquid chromatography
ESI
Electron Spray Ionization
SDS-PAGE
sodium dodecyl sulphate-polyacrylamide gel electrophoresis
Funding
270
We thank the National Key Scientific Instrument and Equipment Development
271
Project of China (2013YQ17052504), the Program for Changjiang Scholars and
272
Innovative Research Team in the University of Ministry of Education of China
273
(IRT_15R55), the seventh group of Hundred-Talent Program of Shanxi Province
274
(2015), and The Key Project of Research and Development Plan of Shaanxi
275
(2017ZDCXL-SF-01-02-01) for financial support.
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Figure Captions
430
Fig. 1. The synthesis pathway of hydroxytyrosol. TyrB, aromatic amino acid
431
aminotransferase;
432
decarboxylase; YahK, aldehyde reductase.
GDH,
L-glutamate
dehydrogenase;
PmKDC,
α-keto
acid
433 434
Fig. 2. UPLC-MS assay of hydroxytyrosol. (a) Mass spectrometry of hydroxytyrosol.
435
(b) UV absorption spectra of hydroxytyrosol.
436 437
Fig. 3. Comparison of the hydroxytyrosol production in each strain.
438 439
Fig. 4. Comparison of the activities of four enzymes in each strain.
440 441
Fig. 5. SDS-PAGE assay of crude enzymes in strain 3 and four enzymes. (M) the
442
molecular-weight marker. E. coli BL21 (DE3) harboring (Lane 1) pRSF-tyrB,
443
(Lane 2) pRSF-gdh, (Lane 3) pRSF-Pmkdc, (Lane 4) pRSF-yahK, and (Lane 5)
444
pRSF-yahK-tyrB and pCDF-gdh-Pmkdc (strain 3).
445 446
Fig. 6. Effects of different conditions on the yield of hydroxytyrosol from strain 3. The
447
effect of (a) different pHs and (b) temperatures on the production of hydroxytyrosol.
448 449
Fig. 7. Time course of hydroxytyrosol synthesis from L-DOPA in strain 3. 21 ACS Paragon Plus Environment
Journal of Agricultural and Food Chemistry
450
Tables
451
Table 1. Strain and plasmids used in this study
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Strain and plasmids
Description
Source
pRSFDuet-1
Double T7 promoters, RSF ori, KanR
Novagen
pETDuet-1
Double T7 promoters, pBR322 ori, AmpR
Novagen
pCDFDuet-1
Double T7 promoters, CDF13 ori, SmR
Novagen
pRSF-yahK
pRSFDuet-1 carrying yahK
This study
pCDF-tyrB-gdh-Pmkdc
pCDFDuet-1 carrying tyrB, gdh and Pmkdc
This study
pRSF-yahK-tyrB
pRSFDuet-1 carrying yahK and tyrB
This study
pCDF-gdh-Pmkdc
pCDFDuet-1 carrying gdh and Pmkdc
This study
pRSF-yahK-Pmkdc
pRSFDuet-1 carrying yahK and Pmkdc
This study
pCDF-tyrB-gdh
pCDFDuet-1 carrying tyrB and gdh
This study
pRSF-yahK-gdh
pRSFDuet-1 carrying yahK and gdh
This study
pCDF-tyrB-Pmkdc
pCDFDuet-1 carrying tyrB and Pmkdc
This study
pRSF-tyrB-gdh-Pmkdc
pRSFDuet-1 carrying tyrB, gdh and Pmkdc
This study
pET-yahK
pETDuet-1 carrying yahK
This study
pET-gdh-Pmkdc
pETDuet-1 carrying gdh and Pmkdc
This study
pRSF-tyrB-gdh-Pmkdc-yahK
pRSFDuet-1 carrying tyrB, gdh, Pmkdc and yahK
This study
Strain 1
E.coli BL21(DE3)/(pRSF-yahK, pCDF-tyrB-gdh-Pmkdc)
This study
Strain 2
E.coli BL21(DE3)/(pRSF-yahK-gdh, pCDF-tyrB-Pmkdc)
This study
Strain 3
E.coli BL21(DE3)/(pRSF-yahK-tyrB, pCDF-gdh-Pmkdc)
This study
Strain 4
E.coli BL21(DE3)/(pRSF-yahK-Pmkdc, pCDF-tyrB-gdh)
This study
Strain 5
E.coli BL21(DE3)/(pRSF-tyrB-gdh-Pmkdc, pET-yahK)
This study
Strain 6
E.coli BL21(DE3)/(pRSF-yahK-tyrB, pET-gdh-Pmkdc)
This study
Strain 7
E.coli BL21(DE3)/(pRSF-tyrB-gdh-Pmkdc-yahK)
This study
452 453 454 455 456 457 458
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Journal of Agricultural and Food Chemistry
Table 2. Comparison of different hydroxytyrosol biosynthesis method Year
Substrate
Concentration
Space-time yield
Reference
2001
tyrosol
16 mM
591.3 mg L-1 h-1
16
2004
tyrosol
3.84 g/L
548.6 mg L-1 h-1
18
2005
tyrosol
1.6 g/L
228.6 mg L-1 h-1
17
2006
tyrosol
4 g/L
571.4 mg L-1 h-1
42
2006
tyrosol
0.8 mM
49.3 mg L-1 h-1
19
2007
tyrosol
2.30 mM
44.3 mg L-1 h-1
43
2009
tyrosol
3.22 mM
49.6 mg L-1 h-1
44
2012
2-phenylethanol
133 mg/L
54 mg L-1 h-1
20
2012
tyrosine
0.19 mM
1.5 mg L-1 h-1
22
2013
tyrosol
≦5 mM
≦77 mg L-1 h-1
2014
3-nitrophenethyl alcohol
0.121 g/L
121 mg L-1 h-1
45
2014
3,4-dihydroxyphenylacetic acid
27.9 mM
204.6 mg L-1 h-1
46
2017
tyrosine
208 mg/L
6.9 mg L-1 h-1
47
2018
tyrosine
268.3 mg/L
8.9 mg L-1 h-1
48
2018
tyrosol
37.39 mM
213.3-319.9 mg L-1 h-1
49
2018
tyrosine
1243 mg/L
25.9 mg L-1 h-1
23
2019
tyrosine
1890 mg/L
52.5 mg L-1 h-1
24
2019
L-DOPA
5.59 g/L
698.8 mg L-1 h-1
This work
460
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Journal of Agricultural and Food Chemistry
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Figure graphics
463
Fig. 1.
464 465
Fig. 2.
466 467 468
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Journal of Agricultural and Food Chemistry
Fig. 3.
470 471
Fig. 4.
472 473 474
Fig. 5.
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475 476
Fig. 6.
477 478
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Journal of Agricultural and Food Chemistry
Fig. 7.
481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496
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Graphic for table of contents
498
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