Accelerating Quinoline Biodegradation and Oxidation with

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Endogenous electrons accelerate quinoline biodegradation and oxidation Qi Bai, Lihui Yang, Rongjie Li, Bin Chen, Lili Zhang, Yongming Zhang, and Bruce E. Rittmann Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.5b03293 • Publication Date (Web): 01 Sep 2015 Downloaded from http://pubs.acs.org on September 2, 2015

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Environmental Science & Technology

Endogenous electrons accelerate quinoline biodegradation and oxidation Qi Bai1, Lihui Yang1, Rongjie Li1, Bin Chen1, Lili Zhang1, Yongming Zhang1*, Bruce E. Rittmann2 1. Department of Environmental Science and Engineering, College of Life and Environmental Science, Shanghai Normal University, Shanghai, 200234, P. R. China 2. Swette Center for Environmental Biotechnology, Biodesign Institute, Arizona State University, Tempe, AZ85287-5701, USA

Qi Bai1, Lihui Yang1, Rongjie Li1, Bin Chen1, Lili Zhang1, Yongming Zhang1 * 1. Department of Environmental Science and Engineering, College of Life and Environmental Science, Shanghai Normal University, Shanghai, 200234, P. R. China *

Email: [email protected]; Telephone: +86 21 64321071; Fax: +86 21 6432 3329 Address: Guilin Road 100, Shanghai, Shanghai Normal University, Shanghai, 200234, P. R. China

Bruce E. Rittmann2 2. Swette Center for Environmental Biotechnology, Biodesign Institute, Arizona State University, Tempe, AZ85287-5701, USA

ACS Paragon Plus Environment


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1

Abstract:

Quinoline, a recalcitrant heterocyclic compound, is biodegraded by a series of

2

reactions that begin with mono-oxygenations, which require an intracellular electron donor.

3

Photolysis of quinoline can generate readily biodegradable products, such as oxalate, whose

4

bio-oxidation can generate endogenous electron donors that ought to accelerate quinoline

5

biodegradation and, ultimately, mineralization.

6

compared for biodegradation of quinoline:

7

photolysis of 1 hour (P1h+B) or 2 hours (P2h+B), and biodegradation by adding oxalate

8

commensurate to the amount generated from photolysis of 1 hour (O1+B) or 2 hours (O2+B).

9

The experimental results show that P1h+B and P2h+B accelerated quinoline biodegradation by

To test this hypothesis, three protocols were

direct biodegradation (B), biodegradation after

10

19% and 50%, respectively, compared to B.

Protocols O1+B and O2+B also gave 19% and

11

50% increases, respectively.

12

2-hydroxyquinoline, accumulated gradually in parallel to quinoline loss, but declined once

13

quinoline was depleted.

14

mono-oxygenation of quinoline, but the inhibition was relieved when extra electrons donors

15

were added from oxalate, whether formed by UV photolysis or added exogenously.

16

oxalate oxidation stimulated both mono-oxygenations, which accelerated overall quinoline

17

oxidation that provided the bulk of the electron donor.

During quinoline biodegradation, its first intermediate,

Mono-oxygenation of 2-hydroxyquinoline competed with


Rapid

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18 19 20


■ INTRODUCTION Quinoline (C9H7N), also called heterocyclic naphthalene or benzene-coupled pyridine, is a typical nitrogenous heterocyclic compound that is recalcitrant to biodegradation 1. 2

It is widely

21

used in dye, rubber, pharmaceutical, food, and chemical industries .

22

water environments with wastewater or surface runoff, and it has relatively high water solubility.

23

Moreover, quinoline and its derivatives are found in urban air, tobacco smoke, seawater, and

24

fish tissue 3-6.

25

growth and development of animals and plants, and they are carcinogenic, teratogenic, and

26

mutagenic to human beings 7-9.

27 28 29 30

Quinoline can migrate to

Quinoline and its derivatives bioaccumulate and can have harmful effects on the

Quinoline degradation is gaining attention 10-13, and biodegradation is a good strategy since it is economical, while many bacteria are known to biodegrade quinoline 10, 14-17. focused on quinoline’s biodegradation pathway and kinetics

Research has

11,18-23

Figure 1 shows a typical quinoline-biodegradation pathway

.

17,24

, which is initiated by two

31

mono-oxygenation reactions that require molecular oxygen (O2) and an intracellular electron

32

carrier (such as NADH + H+, represented as 2H) 25,26.

33

the sequential formation of 2-hydroxyquinoline (2HQ) (step A) and 2,8-two hydroxyquinoline

34

(step B)

35

steps are respectively hydroxylation, mono-oxygenation reaction, and reductive deammination

36

to form a carboxylic acid (2,3-dihydroxyphenyl propionic acid).

37

and dehydrogenation steps lead to full mineralization and the release of 38 electron equivalents

38

(or 38H).

39

steps A through F.

40

10,27-30

.

The mono-oxygenation reactions lead to

Step C is a reduction reaction that cleaves the pyridine ring.

The following

Subsequent hydroxylation

Some of the electron equivalents must be used to provide the net 10H needed for

Steps A and B should be accelerated if an intracellular electron donor (i.e., 2H) is provided

41

from sources other than the steps that mineralize 2,3-dihydroxyphenyl propionic acid.

42

source can be carboxylic acids formed during photolysis of nitrogen containing heterocyclic

43

compounds, as has been shown for pyridine

44

speed up all the downstream steps, leading to faster mineralization of quinoline.

26, 31

.

One

Acceleration of steps A and B ought to

45

In this work, quinoline was illuminated with UV light as a pre-treatment, and the

46

photolyzed quinoline was subsequently biodegraded in an internal circulation baffled biofilm

47

reactor (ICBBR) to investigate the role of a photolytic product (oxalate, C2O42–) as an electron

48

donor for accelerating quinoline biodegradation.

49

between quinoline oxidation and biodegradation of its intermediate (2HQ), since we hypothesize

50

that oxalate should be an electron donor that provides extra electrons to accelerate

51

mono-oxygenation of quinoline and 2HQ.

We especially explored the relationship

The availability of more intracellular electron donor



Page 4 of 27

52

should accelerate the initial removal of quinoline and its overall oxidation.

53

longer photolysis time, which generates more oxalate from quinoline photolysis, should increase

54

the rate of quinoline removal and oxidation.

55

of 2HQ competes electrons with mono-oxygenation of quinoline during their biodegradation;

56

supplying

57

mono-oxygenations, as well as overall oxidation.

extra

electron

donor

should

This means that a

A corollary hypothesis is that mono-oxygenation

counteract

inhibition

58


and

accelerate

both

Page 5 of 27


59

■ MATERIALS AND METHODS

60

Chemicals and preparation of quinoline, and nutrient solutions

61

Quinoline, 2-hydroxyquinoline (2HQ), and other analytical reagents were purchased from

62

Shanghai Sinopharm Chemical Reagent Co. Ltd., China.

For the quinoline-biodegradation

63

experiments, quinoline was added to ultrapure deionized water (18 MΩ, prepared with Millipore

64

(USA) Milli-Q water purifier) to obtain a 15.5 mM (2000-mg/L) stock solution, and quinoline

65

solutions for normal experiments were diluted with tap water to get different initial

66

concentrations according to the need for the biodegradation experiments. 0.4 g CaCl2, 0.2g MgSO4·7H2O, and 0.12g

67

The trace-element solution contained:

68

MnSO4·H2O diluted in 1-L Milli-Q water.

69

g KH2PO4 diluted in 1-L Milli-Q water to yield 2.5 g N/L and 0.5 g P/L stock nutrient solutions,

70

respectively.

Nutrient solutions contained:

9.6 g NH4Cl or 2.2

71 72 73

Quinoline photolysis To evaluate photolysis of quinoline, the quinoline stock solution was diluted to 1.55 mM

74

(200 mg/L) and placed in a glass dish with 2-cm water depth and 15-cm diameter for

75

illumination with UV light having a wavelength of 254 nm, power of 40 W, and light intensity

76

of 1.5 mW/cm2.

77

the solution was stirred by means of magnetic stirrer.

78

quinoline and oxalate concentrations.

79

The lamp was located 10 cm above the water surface. During UV photolysis, Samples were taken to measure

For the experiments of biodegradation after UV photolysis (designated Pxh+B, where xh

80

is 1h or 2 h), quinoline solutions with initial concentrations of 0.47 mM (60 mg/L) and 0.54 mM

81

(70 mg/L) were illuminated by UV light for 1 h and 2 h, respectively, to obtain the same

82

quinoline concentration (0.39 mM) that was added at the start of biodegradation-only

83

experiments.

84 85 86

Acclimation of quinoline-degrading bacteria Activated sludge was taken from the underflow of a secondary clarifier at the Changqiao

87

municipal wastewater treatment plant in Shanghai.

The activated sludge was washed with tap

88

water before acclimation, in which 600 mL sludge and 1400 mL tap water were fed into 2-L

89

beaker to mix well by magnetic stirrer for 10 min, and allowed to settle for 30 min.

90

about 1400-mL of supernatant was poured out.

91

until the supernatant was slightly turbid to get washed sludge.

Then,

The washing protocol was repeated 3 times,


For the first stage of


92

acclimation, the sludge was batch acclimated in a 2-L graduated cylinder with aeration at 30°C

93

for two weeks.

94

sludge, 600 mg glucose, 20 mL trace-element solution, and 12 mL N and P nutrient solution

95

(C:N:P = 100:5:1 in grams).

96

the solids were settled for 30 min when aeration was stopped, and the supernatant was poured

97

out, and the same volume of fresh culture medium was added for following acclimation every

98

day.

The initial mixture was tap water of 1700 mL tap water, 300 mL washed

The acclimations were carried out for two weeks, during which

99

From the fifteenth day, which began the second stage of acclimation, the glucose

100

concentration was decreased gradually from 300 mg/L to zero, and the quinoline concentration

101

was increased gradually from zero to 0.78 mM (100 mg/L), while the N, P, buffer, and

102

trace-element media were unchanged.

103

been acclimated to quinoline biodegradation, since the quinoline was completely removed

104

within 4 hours of addition.

After two weeks of quinoline addition, the sludge had

105

For all experiments in which we evaluated the effects of photolysis or oxalate on quinoline

106

biodegradation, we diluted quinoline into purified water in order to avoid interference by

107

uncontrolled components in tap water.

108

micro-nutrients into the solution for subsequent biodegradation. We used tap water only when

109

we were acclimating the microbial culture to biodegrade quinoline.

After photolysis, we supplemented macro- and

110 111 112

Bioreactor and biofilm formation An internal circulation baffled biofilm reactor (ICBBR), similar to Zhang et al. 26, was

113

employed for quinoline-biodegradation experiments.

The ICBBR, which had a total liquid

114

volume of 730 mL, was divided into top and bottom sections by a segregation board and had

115

220 mL and 510 mL volumes, respectively.

116

bottom section with staggered levels to create up-and-down flow through the lower baffled

117

biofilm section.

118

the upper and lower sections.

119

immerse the ceramic plates for 2 hours to form a preliminary biofilm by adsorption, and then

120

excess sludge was discharged out.

121

solution containing 0.78 mM quinoline for 15 days, at which time the 0.78 mM of quinoline was

122

completely removed within 4 - 8 hours.

123

between top and bottom sections.

Ten ceramic porous plates were installed in the

Liquid medium was circulated by a pump and flowed continuously through The acclimated activated sludge was fed into the reactor to

The biofilm was acclimated with daily batch feeding of a

During acclimation, the solution was circulated

124 125


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126


Quinoline biodegradation Quinoline-biodegradation experiments were carried out in five sets.

127 128

All experiments

were carried out at 30°C and with duplicate runs successively in the same ICBBR. The first set of experiments followed two protocols.

129

The first protocol was direct

130

quinoline biodegradation (designated B).

131

having a concentration of 0.39 mM, the contents were mixed for 5 min in the ICBBR.

132

measured quinoline concentration was 0.31 mM, as carry over solution in the ICBBR diluted the

133

quinoline concentration.

134

The second protocol was quinoline biodegradation after photolysis of different times (designated

135

Pxh+B, where xh is respectively 1h and 2 h).

136

initial quinoline concentrations were, respectively, 0.47 mM (60 mg/L) and 0.54 mM (70 mg/L),

137

and the quinoline concentration at the start of the biodegradation phase in the ICBBR was 0.31

138

mM.

139

and its intermediate, 2-hydroxyquinoline (2HQ), and COD.

140

After quinoline was added into nutrient medium The

Thus, the starting concentration for each experiment was 0.31 mM.

For 1-h and 2-h photolysis experiments, the

Liquid samples were taken at time intervals to measure the concentrations of quinoline

The second set of experiments investigated the effect of addition of oxalate on quinoline

141

biodegradation.

142

mM of oxalate was added into the quinoline solution for biodegradation; these concentrations

143

correspond to the oxalate concentrations after 1 and 2 h of photolysis.

144

designated O1+B and O2+B, respectively.

145

measure quinoline concentrations and COD.

146

The initial quinoline concentration was still 0.31 mM, and 0.01 mM or 0.02

These experiments are

Samples were also taken at time intervals to

The third set of experiments investigated quinoline removal in the presence of added 2HQ,

147

and it tested the degree to which oxalate accelerated quinoline and 2HQ biodegradation

148

simultaneously.

149 150 151

The fourth set of experiments investigated competition between quinoline and 2HQ for electrons, and it involved comparing their removal rates. The fifth set of experiments, which also had an initial quinoline concentration of 0.31 mM

152

in the ICBBR, investigated relationships between intermediate generation and mineralization

153

(COD removal).

154 155

Analytical methods

156

Every liquid sample was filtered through a 0.22-µm membrane filter before measurement.

157

Quinoline and 2-hydroxyquinoline (2HQ) were measured with a high performance liquid

158

chromatograph (HPLC, model: 1100, Agilent, USA) equipped with a diode array detector (DAD)

159

with wavelength of 250 nm, and ZORBAX SB-C18 column (5 µm, 4.6×150 mm, Agilent).



160

The mobile phase was a methanol:water solution (80:20, v/v), the flow rate was 1 mL/min, and

161

the column temperature was 30°C.

162

column (5µm, 4. 6×150 mm), the mobile phase was a mixture of 0.01-mol/L potassium

163

dihydrogen phosphate plus 0.5% methanol, the flow rate was 0.4 mL/min, the column

164

temperature was 25°C, and the detector wavelength was 210 nm.

165

The COD concentration was determined using potassium dichromate oxidation according to

166

standard methods

167

BG-2254, Shanghai Biangan Trade Co. Ltd., China).

32

.

For oxalate, the HPLC was equipped with Aglient HC-C18

The UV-light intensity was measured by an UV light meter (model:


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Page 9 of 27


168

■ RESULTS AND DISCUSSIONS

169

Oxalate generation during quinoline UV photolysis Figure 2 shows that UV photolysis transformed quinoline to form oxalate (one of the

170 171

major products), and longer photolysis time generated more oxalate.

172

linearly for the first three hours, with an oxalate accumulation of 0.05 mM corresponding to loss

173

of 0.33 mM quinoline, or a net generation ratio of 0.14 mol oxalate per mol quinoline lost,

174

which means that UV photolysis generated other products, probably ones less oxidized than

175

oxalate.

176

quinoline loss was 28%, but the COD loss was only 3.7 % (not shown).

177

quinoline concentration of 1.55 mM, 0.08 mM and 0.15 mM oxalate per mM of quinoline lost

178

were generated at 1 and 2 hours of UV photolysis, respectively; these ratios determined the

179

oxalate concentrations used on the O1+B and O2+B experiments:

180

mM (O2+B).

Mineralization was minor during UV photolysis:

Oxalate increased

For UV photolysis of 5 h, For the initial

0.01 mM (O1+B) and 0.02

181 182

Quinoline biodegradation and 2-hydroxyquinoline (2HQ) generation after UV photolysis

183

Quinoline removals corresponding to protocols B, P1h+B, and P2h+B for starting

184

quinoline concentration of 0.31 mM, as well as the fate of its intermediate, 2HQ, are shown in

185

Figure 3.

186

rates.

187

C = [C01−α − kt (1 − α )]1−α .

188

get a common value of α = 0.28, which gives the indicated k values in units of (mg/L)0.72· h–1.

189

The model fits (dashed lines in Figure 3) match well with the experimental data, and P2h+B

190

clearly had the largest k value for quinoline removal, while B had the smallest k value.

191

Comparing the k values in Figure 3 shows that two hours of UV photolysis increased k by 26%

192

over one hour of UV photolysis and by 50% over no photolysis.

Consistent with our hypothesis, longer photolysis time gave faster quinoline removal

The removals fit fractional-order kinetics: r = −

dC = kC α , which is integrated to yield: dt

1

A trial-and-error method was used to estimate the α and k values and

193

Figure 3 also shows that the first mono-oxygenation intermediate, 2HQ, accumulated over

194

the first two to three hours, but then declined as the quinoline concentration approached zero.

195

The kinetics of 2HQ loss are evaluated in a later section.

196 197

Effect of oxalate added on quinoline removal kinetics

198

Based on the oxalate generation ratios from Figure 2, oxalate of 0 mM (B), 0.01 mM

199

(O1+B), or 0.02 mM (O2+B) was added into the quinoline solution having an initial



Page 10 of 27

200

concentration of 0.31 mM for biodegradation experiments.

The quinoline removal kinetics are

201

shown in Figure 4.

202

are consistent with the corresponding k values in Figure 3, which supports that oxalate had the

203

same roles for accelerating quinoline mono-oxygenation reaction whether it was generated by

204

UV photolysis or added independently.

205 206

Competition for electron donor between the first two mono-oxygenation steps

Adding more oxalate led to faster quinoline loss.

The k values in Figure 4

207

The need to transform 2HQ by mono-oxygenation may decelerate quinoline

208

mono-oxygenation due to competition for electrons (2H), but extra electron donors should

209

relieve the competition and accelerate both steps.

210

experiments with an initial quinoline concentration of 0.31 mM.

211

quinoline (B), the second had quinoline plus 0.06 mM of 2HQ (2HQ+B), and the third added

212

0.06 mM 2HP plus 0.02 mM oxalate (2HP+O+B).

213

Figure 5.

214

B), but adding oxalate (comparing 2HP+O+B to B) gave faster kinetics.

215

removals also fit 0.28-order kinetics, and the rate coefficient for 2HQ+O+B was 53% greater

216

than for B, but 2HQ+B was only 80% of B.

217

to competition for endogenous electron donors.

218

competition effect by supplying more electron donors, which accelerated the loss of quinoline in

219

Figure 5 with 2HQ also added, as it did without 2HQ added (Figures 3 and 4).

To test this hypothesis, we carried out three The first experiment had only

The experimental results are shown in

Quinoline biodegradation was slowed when 2HQ was added (comparing 2HQ+B to The quinoline

The inhibition effect of 2HQ most likely was due The addition of oxalate relieved the

220 221 222

Comparison of quinoline and 2HQ mono-oxygenation rates Figure 6 shows quinoline and 2HQ biodegradation rates versus elapsed time for the

223

experimental results in Figure 3.

The quinoline removal rates were computed from r = kC

224

using the k and α values in Figure 3.

225

rate (i.e., ∆(∆C2HQ)/∆t) based on Figure S1 of Supplementary Information (SI).

α

The 2HQ removal rates were computed from its net loss

226

Comparing biodegradation rates for the different photolysis times indicates that, over the

227

first two hours of the experiments, P2h+B had faster quinoline and 2HQ-biotransformation

228

kinetics than P1h+B, which had faster rates than B.

229

experiments switched positions as the quinoline concentration declined to below about 0.1 mM

230

for P2h+B and then P1h+B (Fig. 3).

231

2HQ biodegradation was fastest for P2h+B, even though the concentration of 2HQ was similar

232

in all experiments (Fig. 3).

233

increased the kinetics of the second mono-oxygenation, as well as the first mono-oxygenation

For quinoline, the relative rates among the

The most important trend in Fig. 6 is that the kinetics for

This supports that addition of oxalate (from UV photolysis)


Page 11 of 27

234 235


(Fig. 1). Figure 6 also shows that quinoline biodegradation rates were faster than the rates for 2HQ

236

until quinoline was almost completely depleted.

Their average transformation rates (raverage)

237

over the first 2 h are listed in Figure 6.

238

that internal electron donor was preferentially utilized for the first mono-oxygenation.

239

2HQ continued to accumulate as long as quinoline was present to be transformed.

240

quinoline biodegradation, 2HQ competed for electrons with quinoline, but quinoline

241

transformation rates always higher than 2HQ transformation rates until the quinoline

242

concentration was near zero.

The consistently faster kinetics for quinoline implies Thus, During

243 244 245

Relationship 2HQ biodegradation and quinoline oxidation Experiments were conducted to map the coincident patterns of quinoline loss, 2HQ

246

generation, and COD removals in B experiments, and the results are shown in Figure 7.

247

2HQ was generated gradually in parallel with quinoline loss, the COD dropped slowly until

248

2HQ began decreasing.

249

mono-oxygenation.

250

generation of internal electron donors for the initial mono-oxygenation steps.

251

While

This trend supports that the rate of overall oxidation was tied to 2HQ

The acceleration of overall oxidation also resulted in an increased rate of

Figure 8 shows that that the degree of COD removal at the end of the B, P1h+B, P2h+B,

252

O1+B, and O2+B experiments had similar trends as for quinoline removal:

P1h+B and O1+B

253

had the similar degrees (80 and 81%), P2h+B and O2+B had also the similar degrees (90 % and

254

91%), and all were higher than B (72%).

255

quinoline oxidation increased when the addition of the electron donor accelerated 2HQ

256

biotransformation.

These COD results support that the degree of

257 258 259

The relative role of extra electron donor for accelerating quinoline and 2HQ

260

biodegradation based on H-production rates

261

Figure 1 indicates that initial steps of quinoline and 2HQ biodegradation should depend

262

on available electron-donor equivalents, whether supplied endogenously from oxidation of

263

2,3-dihydroxyphenyl propionic acid (C9H10O4) (Fig. 1)17, 24 or exogenously by oxalate (C2O42–).

264

For mineralization of quinoline alone, each mole of quinoline requires a net of 10 H for steps A

265

– F, leaving a net of 28 H for respiration and synthesis.

266

H for steps B – F, leaving a net 30 H for respiration and synthesis.

267

electron donor (generated from UV photolysis or added exogenously), its full oxidation provides

Similarly, full oxidation of 2HQ uses 8


When oxalate is the extra


268

Page 12 of 27

2 H/mol oxalate. To analyze quantitatively the relative impacts of added and endogenous electron donor,

269 270

we did an H-equivalent accounting for the experiments corresponding to Figure 3.

We

271

assumed that oxalate was completely oxidized and provided electrons for quinoline and 2HQ

272

mono-oxygenation.

273

experiment (Figure 7 or 8), while oxidation was, respectively, 80% and 90% by the end of the

274

P1h+B and P2h+B experiments (Figure 8).

275

quinoline and 2HQ experiments, respectively.

276

were greater for quinoline than for 2HQ, since the net H generated by 2HQ oxidation is greater

277

than for quinoline oxidation:

278

required for the reactions was greater for quinoline than for 2HQ:

279

versus 8 H/mol for 2HQ.

280

higher degree of quinoline oxidation, not from oxalate oxidation by itself.

281

of oxalate played a stimulatory role based on its ability to be oxidized rapidly, while it took time

282

for 2,3-dihydroxyphenyl propionic acid, which had to be formed from 2HQ mono-oxygenation

283

(or quinoline mono-oxygenation), to be completely oxidized and release all of its H equivalents.

284

This stimulatory effect of oxalate underscores the value of intimate coupling of photo(cata)lysis

285

and biodegradation, which can rapidly provide readily available electron donor 22, 23.

We also assume that quinoline was 72% oxidized by the end of B

Tables 1 and 2 provide the accounting analyses for The relative effects of the added electron donor

30 H/mol for 2HQ versus 28 H/mol for quinoline.

Also, the H

10 H/mol for quinoline

The large majority of the increase in donor available was from a Thus, the addition

Tables 1 and 2 also compare normalized raverage values to the normalized net generation of

286 287

H.

For quinoline and 2HQ, the impact on raverage was parallel to the increase in intracellular

288

donor normalized to the total electron equivalents generated.

289

normalized raverage values in the last lines of Tables 1 and 2 further supports that electrons may

290

have been preferentially utilized for the first mono-oxygenation, since relative raverage values for

291

quinoline always were larger than for 2HQ.

292

stimulate the initial mono-oxygenation steps, which led to more oxidation that increased the

293

availability of intracellular donor for all donor-requiring steps.

294

oxalate underscores the value of generating readily biodegradable products by photo(cata)lysis.

In addition, comparing the

This shows that the main effect of oxalate was to

The stimulation impact of

295 296

■ ACKNOWLEDGMENTS

297

The authors acknowledge the financial support by the National Natural Science

298

Foundation of China (50978164), Special Fund of State Key Joint Laboratory of Environment

299

Simulation and Pollution Control (13K09ESPCT), Key project of basic research in Shanghai

300

(11JC1409100), the United States National Science Foundation (0651794).


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302

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(9) Hirao, K.; Shinohara, Y.; Tsuda, H.; Fukushima, S.; Takahashi, M. Carcinogenic activity of quinoline on rat liver. Cancer Research, 1976, 36, 329–335 (10) Qiao, L.; Wang, J. Biodegradation characteristics of quinoline by Pseudomonas putida. Bioresource Technology, 2010, 101, 7683-7686.

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characteristics and metabolic products of quinoline by a Pseudomonas strain. Bioresource

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Technology, 2009, 100, 5030–5036.

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glucose in dual substrates system. Bull Environ Contam Toxicol, 94(3): (2015) 365-369.

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(15) Grant, D. J.; Al-Najjar, T. R. Degradation of quinoline by a soil bacterium. Microbios, 1976,

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Aerobic biodegradation of 4-Methylquinoline by a soil bacterium. Applied and

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mechanism of 8-hydroxycoumarin reduction. J. Mol. Biol, 2006, 361, 140–152.

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(29) Thomsen, A. B. Degradation of quinoline by wet oxidation—kinetic aspects and reaction mechanisms. Wat. Res., 1998, 32(1),136-146.

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Pollution Control Federation, Washington DC, 2001.



Page 16 of 27

386 387 388

Captions of Tables and Figures:

389

quinoline experiments and comparison to the increase in quinoline transformation rates

Table 1.

Accounting of exogenous and endogenous electron donors available during the

390 391

Table 2.

Accounting of exogenous and endogenous electron donors available during the 2HQ

392

experiments and comparison to the increase in quinoline transformation rates

393

Representative quinoline-biodegradation pathway based on Shukla 17 and Schwarz et

394

Figure 1.

395

al., 24.

396

products.

2H represents an intracellular electron donor.

397 398 399

Figure 2.

Oxalate (C2O42–) generation during quinoline loss from UV photolysis.

400

Figure 3.

401

different protocols in experimental set 1.

402

the averages of two runs.

403

values (units of mM0.72•h–1) for 0.28-order kinetics of quinoline.

The indicated e– equivalents are associated with C in quinoline and its biodegradation

Quinoline biodegradation together with 2-hydroquinoline (2HQ) generation by (E) symbols represent experimental values and are

(C) lines represent calculated values based on the indicated best-fit k

404 405

Figure 4. Effect of oxalate added on quinoline biodegradation, here (E) symbols represent

406

experimental values and are the averages of two runs. 0.72

(C) lines represent calculated values –1

407

based on the indicated best-fit k values (units of mM

•h ) for 0.28-order kinetics.

408 409

Figure 5.

410

represent experimental values and are the averages of two runs.

Effect of added 2HQ and oxalate on quinoline biodegradation. 0.72

(E) symbols

(C) lines represent calculated

–1

411

values based on the indicated best-fit k values (units of mM

•h ) for 0.28-order kinetics.

412 413 414

Figure 6.

Quinoline and 2HQ transformation rates during biodegradation of quinoline.

415

Figure 7.

Relationships among quinoline, 2HQ, and COD concentrations.

416 417

Figure 8.

Effect of protocols on the COD-removal percentages.


Page 17 of 27

418 419


Table 1.

Accounting of exogenous and endogenous electron donors available during the

quinoline experiments and comparison to the increase in quinoline transformation rates Electron donor added (mM / e– meq/L) H needed for reactions (meq/L) Net H generated from quinoline loss (meq/L) Net H generated from oxalate loss (meq/L) Total Net H generated (meq/L) Normalization of Net H generated to the value for no donor added Normalization of Net H generated to the H needed for the H-requiring reactions Quinoline-removal raverage value (mM/h) Normalization of raverage value to the raverage value for no added donor

No donor added

Oxalate Added

0/0

0.01 / 0.02

0.02 / 0.04

10

10

10

28

28

28

0

0.02

0.04

28×0.72 (=20.16)

28×0.8+0.02 (=22.42)

28×0.9+0.04 (=25.25)

1

1.11

1.25

2.02

2.24

2.52

0.100

0.118

0.135

1

1.18

1.35

420



421 422

Table 2.

Page 18 of 27

Accounting of exogenous and endogenous electron donors available during the 2HQ experiments and comparison to the increase in quinoline transformation rates Electron donor added (mM / e– meq/L)

No donor added

Oxalate Added

0/0

0.01 / 0.02

0.02 / 0.04

8

8

8

30

30

30

0

0.02

0.04

30×0.72 (=21.60)

30×0.8+0.02 (=24.02)

30×0.9+0.04 (=27.04)

1

1.11

1.25

2.70

3.00

3.38

2HQ-removal raverage value (mM/h)

0.080

0.090

0.099

Normalization of raverage value to the raverage value for no added donor

1

1.13

1.24

H needed for reactions (meq/L) Net H generated from quinoline loss (meq/L) Net H generated from oxalate loss (meq/L) Total Net H generated (meq/L) Normalization of Net H generated to the value for no donor added Normalization of Net H generated to the H needed for the H-requiring reactions

423 424


Page 19 of 27


425

426 427 428

Figure 1.

429

al., 24.

430

Representative quinoline-biodegradation pathway based on Shukla 17 and Schwarz et The indicated e– equivalents are associated with C in quinoline and its biodegradation products.

2H represents an intracellular electron donor.



Page 20 of 27

1.6

1.2 0.04 0.8

Oxalate (mM)

Quinoline (mM)

0.06

0.02

0.4

Quinoline Oxalate

0

0 0

1

2

3

4

5

T (h)

431 432

Figure 2.

Oxalate (C2O42–) generation during quinoline loss from UV photolysis.


Page 21 of 27


433

0.3 2

C (mM)

B: k =0.16, R =0.996 0.2

Quinoline (E) Quinoline (C) 2HQ

0.1

0 0.3 0

1

2

3

C (mM)

T (h)

Quinoline

2

0.2

P1h+B: k =0.19, R =0.959

Quinoline (C) 2-HQ

0.1

0 0.3 0

1

2

3

T (h)

C (mM)

4

0.2

4

Quinoline 2

P2h+B: k =0.24, R =0.959

Quinoline (C) 2-HQ

0.1 0 0

1

2

3

4

T (h)

434 435 436 437 438

Figure 3.

Quinoline biodegradation together with 2-hydroquinoline (2HQ) generation by

different protocols in experimental set 1. the averages of two runs.

(E) symbols represent experimental values and are

(C) lines represent calculated values based on the indicated best-fit k

values (units of mM0.72•h–1) for 0.28-order kinetics of quinoline.

439 440



Quinoline(mM)

0.3

Page 22 of 27

B(E)

B (C)

O1+B(E) O2+B(E)

O1+B(C) O2+B(C)

0.2

0.1

B:

2

k =0.16, R =0.995 2

OA1+B: k =0.18, R =0.992 2

OA2+B: k =0.23, R =0.999

0 0

0.5

1

1.5

2

2.5

3

3.5

T (h)

441 442 443 444

Figure 4. Effect of oxalate added on quinoline biodegradation, here (E) symbols represent experimental values and are the averages of two runs.

(C) lines represent calculated values

based on the indicated best-fit k values (units of mM0.72•h–1) for 0.28-order kinetics.


Page 23 of 27


445 446

Quinoline(mM)

0.3

2HQ+B (E)

2HQ+B (C)

B (E) 2HQ+O+B (E)

B (C) 2HQ+O+B (C)

0.2

0.1

2

2HQ+B:

k =0.12, R =0.993

B:

k =0.15, R =0.992

2

2

2HQ+O+B: k =0.23, R =0.998 0 0

0.5

1

1.5

2

2.5

3

T (h)

447 448 449 450

Figure 5.

Effect of added 2HQ and oxalate on quinoline biodegradation.

represent experimental values and are the averages of two runs. 0.72

values based on the indicated best-fit k values (units of mM


(E) symbols

(C) lines represent calculated •h–1) for 0.28-order kinetics.


Page 24 of 27

Transformation rateTransformation (mM/h) rate (mM/h)

451

0.16

P2h+B: r

0.12

P1h+B: r B: r

0.08

average

= 0.135 mM /h

= 0.118 mM /h average = 0.100 mM /h

average

P2h+B P1h+B

0.04

Quinoline

B

0 0.12 0

1

2 T (h)

0.08 0.04

P2h+B 0.099 mM /h P1h+B = 0.090 mM /h average B r average = 0.080 mM /h

P2h+B: r P1h+B: r B:

average3=

4

2HQ

0 0

1

2

3

4

T (h)

452 453

Figure 6.

Quinoline and 2HQ transformation rates during biodegradation of quinoline.


Page 25 of 27


454

100

0.3

Quinoline (mM)

C (mM)

COD (mg/L)

0.2

60 40

0.1

COD (mg/L)

80

2HQ (mM)

20 0

0 0

1

2

3

4

T（h）

455 456

Figure 7.

Relationships among quinoline, 2HQ, and COD concentrations.



Page 26 of 27

457

COD removal percentage (%)

100

75

50

25

0 B

P1h+B

O1+B

P2h+B

O2+B

Protocol

458 459

Figure 8.

Effect of protocols on the COD-removal percentages.


Page 27 of 27


460 461 462

TOC art

463


Accelerating Quinoline Biodegradation and Oxidation with

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