Biodegradation Phenol

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Chinese Journal of Chemical Engineering, 16(5) 796800 (2008)

Biodegradation of Phenol and 4-Chlorophenol by the Mutant

Strain CTM 2*

JIANG Yan ()1,2,3,**, REN Nanqi ()2, CAI Xun ()1, WU Di ()1, QIAOLiyan ()1 and LIN Sen ()11 Department of Chemical Engineering, Daqing Oilfield Engineering Limited Company, Daqing 163712, China2 School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090, China3 School of Life Sciences and Chemistry, Harbin University, Harbin 150016, China

Abstract The biodegradations of phenol and 4-chlorophenol (4-cp) were studied using the mutant strain CTM 2obtained by the He-Ne laser irradiation on wild-type Candida tropicalis. The results showed that the capacity of theCTM 2 to biodegrade 4-cp was increased up to 400 mgL

1 within 59.5 h. In the dual-substrate biodegradation, bothvelocity and capacity of the CTM 2 to degrade 4-cp increased with low-concentration phenol. A total of 400 mgL

14-cp was completely degraded within 50.5 h in the presence of 300 mgL

1 phenol. The maximum 4-cp biodegrada-tion could reach 440 mgL

1 with 120 mgL1 phenol. Low-concentration 4-cp caused great inhibition on the CTM

2 to degrade phenol. In addition, the kinetic behaviors were described using the kinetic model proposed in this lab.Keywords biodegradation, phenol, 4-chlorophenol, the mutant strain CTM 2

1 INTRODUCTION

Phenol and its derivatives are ubiquitous pollut-ants in aquifers and wastewaters [1]. Chlorinated or-ganic compounds are one of the most importantgroups of xenobiotic chemicals. Toxic low molecularweight chlorophenols are persistent in the environ-ment, which increases risk to health [2-4]. 4-cp hasbeen extensively used in the chemical industry as in-termediate product in herbicide, insecticide, and fun-gicides [5-7]. They have been characterized asfirst-priority pollutants by both the European Union

(EU) and the United State Environmental ProtectionAgency (US EPA) [8, 9]. Because of the toxic proper-ties of both phenol and 4-cp, the effective removal ofthose compounds from industrial aqueous effluents isof great practical significance for environmental pro-tection. At present, some researches on removal ofphenol and chlorophenol have been reported, andconsequently, the search for the approaches to com-pletely get rid of such kinds of pollutants has becomea hot topic in the environmental science [10-12].

Biotechnology plays a key role for the removalof phenolic compounds [13, 14]; hence, their biodeg-radations have been widely studied, for example, us-

ing bacterial and filamentous pure cultures, mixedcultures, and yeast cultures [15-18]. Fialov et al[19].reported that the yeast Candida maltosa had the po-tential to degrade phenol in the concentration of up to1700 mgL

1. Zouari et al [20]. reported that the fun-

gusPhanerochaete chrysosporium had the potential todegrade 4-cp in the concentration of up to 300 mgL

1.

Among those studies, C. tropicalis was given highimportance because of its strong phenol-degradingcapacity and wide existence in the sites with phenol[21-23]. In our lab, a wild strain C. tropicalis was iso-lated from acclimated activated sludge, which was

capacity to degrade phenol up to 2000 mgL1

[24],and He-Ne laser was then used to irradiate the wildC.tropicalis, and consequently the mutant strain CTM 2was obtained [25]. The objective of the present studywas to investigate biodegradation behaviors of phenoland 4-cp as single and dual substrates by the mutantstrain CTM 2.

2 MATERIALS AND METHODS

2.1 Microorganism and cultivation conditions

Wild-type C. tropicalics was isolated from accli-mated activated sludge taken from Tianjin Gasworksin China. He-Ne laser (Model HN-1000, made inGuangzhou Laser Technology Applied Institute) wasused for the irradiation of wildC. tropicalis. The mu-tant strain CTM 2 was obtained based on its stabilityin the continuous transfers and the maximum potentialfor phenol biodegradation after repeated screens [25].

The CTM 2 and its parent strain were maintainedin YEPD medium (yeast extract, 10 gL

1; peptone, 20

gL1

; dextrose 20 gL1

; agar, 18 gL1

) [26]. A min-eral salt medium supplemented with phenol and 4-cpwas applied for the biodegradation studies [24]. All the

cultivation was conducted at 30C, and the shakingflasks were incubated in a rotary shaker at the speed of200 rmin

1.

2.2 Biodegradation of phenol and 4-cpbiodegradations

The experiments were strated with inoculation ofC. tropicalis from nutrient agar slants into 10 ml ofYEPD medium. After 16 h of incubation, 2 ml of thiscell culture was added to 500 ml shaking flasks with

Received 2008-01-24, accepted 2008-05-15.* Supported by the Science and Technology Innovative Talents Foundation of China (2006RFQXS070), the Youth Academic

Cadreman Project of Heilongjiang Province (1152G068), Scientific Research Fund of Heilongjiang Province (11523063) andthe Science Foundation for Post Doctorate of China (20070410268).

** To whom correspondence should be addressed. E-mail: [email protected]


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100 ml fresh YEPD medium. Cells grown in latephase of the growth curve were harvested as inoculum.Five percent of the subculture (OD6001.3) was in-oculated into the mineral salt medium with varyinginitial phenol and/or 4-cp at an interval. In the processof batch culture, all samples were periodically meas-ured for the biomass and substrate concentrations. Allthe experiments were repeated three times.

2.3 Analytical methods

Cell density was monitored spectrophotometri-cally by measuring the absorbance at wavelength 600nm [27]. Biomass concentrations based on dry masswere then measured by filtering cell suspension withthe filler and drying the filter paper and cells to a con-stant mass for 24 h at 105C. To measure concentra-tion of residual substrate, right after measurements of

optical density, samples of suspended culture werecentrifuged at 7500 rmin1

for 10 min. The free cellsupernatants were used to determine the substrateconcentration by high performance liquid chromatog-raphy using a LabAlliance (model SeriesIII) system,with a C18 column (250 mm4.6 mm, LabAlliance,U.S.A). Elution was performed with 400/300 (volumeratio) methanol/water at a flow rate of 1.0 mlmin

1,

and detection was realized using a UV detector (Model500, LabAlliance, U.S.A.) at 280 nm. The retention timefor phenol was 4.89 min and for 4-cp was 8.98 min.

3 RESULTS AND DISCUSSION

3.1 4-cp biodegradation

3.1.1 Comparison of biodegradation between wildand mutated C. tropicalis

The maximum 4-cp biodegradation of wild C.tropicalis occurred at 350 mgL

1. Comparison be-

tween the wild-type C. tropicalis and its mutant CTM2 to degrade 350 mgL

14-cp is shown in Fig. 1. It is

obvious that the mutant strain CTM 2 grew faster andpossessed the higher velocity to degrade 4-cp than itsparent strain. It took 4.5 h less for the mutant CTM 2,and the final concentration was a little higher thanwild strain (8.25 mgL

1), which was because 4-cp

inhibition on the mutant CTM 2 was smaller than thaton its parent strain.

Figure 1 Comparison of biodegradation between wild-typeC. tropicalis and its mutant CTM 2 for 350 mgL

14-cp

wild;mutant

3.1.2 Maximum 4-cp biodegradationThe maximum phenol biodegradation has been

previously studied, and the CTM 2 possessed the ca-pacity to degrade 2600 mgL

1phenol [25]. The bio-

degradation behavior of CTM 2 in the utmost 4-cpconcentration from 360 mgL

1to 400 mgL

1at an

interval of 20 mgL1 is described in Fig. 2. With theincreased concentration of 4-cp, cell growth lag stagebecame longer and the specific degradation rate de-creased. A total of 400 mgL

14-cp was used within

59.5 h by the mutant with the larger capacity than wildstrain (350 mgL

1). It was impressive because there

were few reports on the 4-cp biodegradation beyond300 mgL

1.

Figure 2 Cell growth and substrate degradation of theCTM 2 for 360-400 mgL1 4-cp 360 mgL

1; 380 mgL1; 400 mgL

1

3.2 Phenol and 4-cp dual-substrate biodegradation

3.2.1 Effect of phenol on 4-cp biodegradation velocityFigure 3 shows the effect of different concentra-

tions of phenol on the CTM 2 to degrade 400 mgL1

4-cp. In dual-substrate system, it took the CTM 2 thelonger time to completely degrade phenol with theincrease of phenol concentration. However, the mosteffective 4-cp biodegradation with the same concen-tration occurred in the presence of 300 mgL

1phenol,

and 400 mgL1

4-cp was completely degraded within50.5 h. It can be observed from the figure that 4-cpbiodegradation velocity increased with the phenolconcentration from 0-300 mgL

1and then decreased.

Even as a kind of toxic compound for cell, in dual-

substrate system, phenol took the effect to provide

Figure 3 Effect of phenol on 400 mgL1 4-cp biodegrada-tion behavior by the CTM 2 with different initial phenolconcentrations from 0 to 800 mgL

1 0 mgL

1;100 mgL1;200 mgL1;300 mgL1;

500 mgL1;800 mgL1


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carbon and energy for cell, which took the dominationin this stage and lasted with the phenol concentrationof 0-500 mgL

1. Only when the concentration of

phenol was more than 500 mgL1

, its toxic propertyprevailed and weakened its acceleration and substrateinhibition limited cell growth, thus cell underwent thelong lag and therefore, 4-cp biodegradation sloweddown. At such phenol concentration, although thestrong toxicity existed in dual-substrate system, bio-degradation could still proceed. However, it wouldtake the longer time than single-substrate biodegrada-tion of 400 mgL

14-cp. The two effects of phenol,

both inhibition as a toxic compound and accelerationas a carbon, simultaneously existed in dual-substratesystem. They competed with each other, which resultedin the optimal phenol concentration (300 mgL

1).

Once phenol concentration was more than 500 mgL1

,inhibition began to prevail, and it took the CTM 2 alonger period of time to degrade all the substrates than

to degrade single 4-cp. In the experiments, whenhigher-concentration phenol (over 800 mgL

1) was

introduced into the medium, neither phenol nor 400mgL

14-cp was used by the CTM 2.

3.2.2 Effect of phenol on 4-cp biodegradationcapacity

Phenol could not only accelerate the velocity butalso increase the capacity for 4-cp biodegradation. Fig. 4describes the biodegrading behavior of 440 mgL

1

4-cp with changing phenol concentrations from 60mgL

1to 180 mgL

1. A total of 440 mgL

14-cp

could be degraded in the presence of 80-160 mgL1

phenol. In 120 mgL

1phenol solution, after the initial

biodegradation for 4 h, 4-cp began to degrade withoutany residual phenol in dual-substrate system. Eventu-ally, the CTM 2 possessed the maximum biodegrada-tion velocity, and all substrates could be completelydegraded within 63 h. It was also observed in thesamples with 60 mgL

1and 180 mgL

1phenol that

4-cp could not be used by the CTM 2. Despite thesame experimental results, the biodegrading behaviorswere different. From Figs. 4 and 5, it can be observedthat 60 mgL

1phenol was degraded very quickly but

cell concentration only increased a little, whereas 180mgL

1phenol could not be used by cell all along and

cell concentration was kept as a constant. The phenol

concentration of 60 mgL1 was consumed to synthe-size new cells and overcome the substrate inhibition.However, after phenol was consumed, cell growth ter-minated, and the total biomass (25.32 mgL

1) could

not overcome the inhibition of 4-cp, and the concen-tration of 4-cp was kept as constant during the long-timedetermination. Thus, although 60 mgL

1phenol was

used by cells, 4-cp biodegradation could not occur. Itwas further proved that phenol provided carbon for theinitiation of the biodegradation and increased the me-tabolism velocity and capacity of the strain.

3.2.3 Effect of 4-cp on phenol biodegradation

The degradtion of 2500 mgL

1

phenol by CTM2 in the presence of 4-cp from 0 to 30 mgL1

isshown in Fig. 6. Obviously, very little 4-cp could cre-ate inhibition on phenol biodegradation for the CTM 2.In dual-substrate system, even 30 mgL

14-cp could

bring about the termination of phenol biodegradation.In the two samples of 10 mgL

1and 20 mgL

14-cp,

cells underwent very long lag phase, and 2500 mgL1

phenol was completely degraded within 74 h and 79 h,respectively, which was evidently longer than sin-gle-substrate biodegradation. It was worth noticingthat regardless of the concentration of phenol and 4-cp,the mutant strain CTM 2 always preferentially usedphenol, and 4-cp biodegradation always occurred at

Figure 4 Effect of phenol on 440 mgL

1 4-cp biodegrada-tion behavior by the CTM 2 with different initial phenolconcentrations from 60 to 180 mgL

160 mgL1;80 mgL1;100 mgL1; 120 mgL1;140 mgL1;160 mgL1; 180 mgL1

Figure 5 Cell concentrations in dual-substrate systemwith 440 mgL

14-cp and different initial phenol concen-

trations before complete degradation of phenol60 mgL1;80 mgL1;100 mgL1; 120 mgL1;140 mgL1;160 mgL1; 180 mgL1

Figure 6 Effect of 4-cp on the CTM 2 for phenol biodeg-radation behavior with 2500 mgL

1 phenol and differentinitial 4-cp concentrations0 mgL1;10 mgL1; 20 mgL1;30 mgL1


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the end stage of phenol biodegradation. That is, inphenol and 4-cp dual-substrate biodegradation system,the biodegradation time was completely determinedby 4-cp biodegradation. This is proven in Figs. 3 and 4.

3.3 Phenol and 4-cp dual-substrate biodegrada-tion kinetics

Because of the phenol inhibition on cell growth,the Haldanes equation was selected for assessing thedynamic behavior of the CTM 2 grown on phenol [24, 28].However, 4-cp imposed a stronger inhibition thanphenol on the cells; the Haldanes equation was thusnot suitable to describe the 4-cp biodegradation.Therefore, inhibition constant for cell growth (

1iK )

was appended in the Eq. 1.

m2 2X 2 3

2 2S2 2

i2 i2

S

S SK SK K

=

+ + +

(1)

Kinetic equations of the CTM 2 were obtained byregression using MATLAB software:

Cell growth: 2X 2 32 2

2

5.28

1064.65.10 1863.1

S

S SS

=

+ + +

The value of the root mean square of the residu-als at these parameters was small (0.084). Obviously,max was higher than wild strain (max2.78 h

1).

Substrate biodegradation behavior was describedusing the Eq. (2).

S XA B = + (2)

Thus, 4-cp biodegradation:0 0S2 X20.502 = +

0.0972

( 0.967)R =

It was clear that the simulated values of thegrowth and degradation kinetics agreed well with theexperimental data. The parameter values indicated thatit was easier for 4-cp to be metabolized by the mutantcells than by the wild strain.

On the basis of the experimental results (bothsubstrate inhibition on the cells and mutual inhibitionof phenol and 4-cp) and the fact that the inhibitoryeffect of 4-cp on cell growth was larger than that ofphenol, by quasi steady state approximation, thedual-substrate kinetic equations of the strain for thephenol and 4-cp biodegradation were obtained:

X1 2X1

T T

2 21 2

max1 1 S1 1 2

i1 i2

13

2 221 2 1 2 1 2

i2

k X

X X

S fSS K S fS

K K

fSKS S MS S QS S

K

+

= =

= + + + + +

+ + +

(3)

and

X2 2X2

T T

k X

X X

+ = =

2 3 22 2 1 1

max 2 2 S2 2

i2 i2 i1

12 2

1 2 1 2 1 2

1 1 1

S S S S S K S

K K f fK

KS S MS S QS Sf f f

= + + + + + +

+ +

(4)

Equations (3) and (4) are cell growth kineticequations of phenol and 4-cp biodegradation indual-substrate system, respectively.

On the basis of the Eqs. (3) and (4) mentionedabove, the total cell specific growth rate could be ob-tained as

X X1 X2 = + (5)

( max1 , KS1, Ki1) and ( max2 , KS2, Ki2, i2K )

could be obtained separately from the kinetics of theindividual cell growth on the phenol alone and 4-cpalone, respectively.

Using the experimental data, the parameter val-ues of cell growth kinetic equation were obtained asfollows:

53.8 10f = , 94.2 10K = , 73.9 10M = ,52.6 10Q = .

The specific degradation rates of phenol and 4-cpin phenol and 4-cp dual-substrate system could berepresented based on the experimental data.

For phenol:

S1 X15.13 0.026 = + 2( 0.970)R =

For 4-cp:

S2 X20.714 0.038 = + ( )2 0.959R =

According to R2, it was concluded that the re-

gression curve was very well consistent with the ex-perimental data. The kinetic equations were suitable todescribe the biodegradation behavior of the CTM 2 indual-substrate system.

4 CONCLUSIONS

The mutant strain CTM 2 possessed the strong

capacity to degrade phenolic compounds. In dual-substrate biodegradation system, low-concentrationphenol could enhance 4-cp biodegradation of theCTM 2. Phenol always played two roles: to accelerate4-cp biodegradation as a carbon and to inhibit cellgrowth as a toxic compound. Different phenol quan-tity decided its dominancy. However, regardless of theratio of phenol and 4-cp concentration, the CTM 2always used phenol first, and 4-cp biodegradation oc-curred at the end phase of the phenol biodegradation.The biodegradation time completely depended on theconsumption time of 4-cp biodegradation. Very little4-cp could greatly inhibit phenol biodegradation. Inaddition, the kinetic models for the specific growth

and degradation rates of phenol and 4-cp as the singleand dual substrates were obtained, and the simulatedvalues of these models agreed well with the experi-mental data.


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NOMENCLATURE

A growth associated constant for substrate consumption

B non-growth associated constant for substrate consumption, h1

f substrate interaction coefficient

K,M, Q substrate interaction coefficient, (mgL1

)1

Ki1 self-inhibition constant of phenol, mgL

1Ki2 self-inhibition constant of 4-cp, mgL

1

i2K self-inhibition constant of 4-cp, (mgL1

)2

KS1 saturation constant for cell growth on phenol, mgL1

KS2 saturation constant for cell growth on 4-cp, mgL1

S initial substrate concentration, mgL1

t time, h

X biomass concentration, mgL1

X substrate degradation rate, mgLh1

max maximum specific cell growth rate on phenol (max1) or on 4-cp

(max2), h1

S specific substrate degradation rate, h1

S1 specific degradation rate of phenol in dual substrates, h1

S2 specific degradation rate of 4-cp in dual substrates, h1

X overall specific growth rate in dual substrates, h1

X1 specific growth rate on phenol in dual substrates, h1

X2 specific growth rate on 4-cp in dual substrates, h1

Superscripts

0 single growth substrate

Subscripts1 growth substrate, phenol

2 growth substrate, 4-cp

REFERENCES

1 Kavitha, V., Palanivelu, K., The role of ferrous ion in fenton andphoto-fenton processes for the degradation of phenol, Chemosphere,

55, 1235-1243 (2004).

2 Ji, X.L., Zhang, J.L., Li, W., Han, Z.T., Wang, Y.P., Effect of sub-strate permeation on kinetics of phenol biodegradation, Chin. J.

Chem.Eng., 11 (2), 151-155 (2003).

3 Ai, Z., Yang, P., Lu, X.H., Degradation of 4-chlorophenol by a mi-crowave assisted photocatalysis method, J. Hazard. Mater., 124,

147-152 (2005).

4 Zhao, D., Xu, X. , Lei, L., Wang, D., Degradation of 4-chlorophenolsolution by synergetic effect of dual-frequency ultrasound with Fen-

ton reagent, Chin.J. Chem.Eng., 13 (2), 204-210 (2005).

5 Kim, J.H., Oh, K.K., Lee, S.T., Biodegradation of phenol andchlorophenols with defined mixed culture in shake-flasks and a

packed bed reactor,ProcessBiochem., 37, 1367-1373 (2002).

6 Xu, X., Wang, D., Catalytic wet air oxidation of o-chlorophenol inwastewater, Chin.J. Chem.Eng., 11 (3), 352-354 (2003).

7 Yuan, S.H., Lu, X.H., Comparison treatment of various chlorophe-nols by electro-Fenton method: Relationship between chlorine con-

tent and degradation,J.Hazard.Mater., 118, 85-92 (2005).

8 Ye, F.X., Shen, D.S., Acclimation of anaerobic sludge degradingchlorophenols and the biodegradation kinetics during acclimation

period, Chemosphere, 54, 1573-1580 (2004).9 Ruzgas, T., Emneus, J., Gorton, L., Marko, V.G., The development

of a peroxidase biosensor for monitoring phenol and related aromatic

compounds,Anal. Chem.Acta, 31, 245-253 ( 1995).

10 Yamada, K., Akiba, Y., Shibuya, T., Kashiwada, A., Matsuda, K.,

Hirata, M., Water purification through bioconversion of phenol

compounds by tyrosinase and chemical adsorption by chitosan

beads,Biotechnol.Prog., 21, 823-829 (2005).

11 Garibay-Orijel, C., Ros-Leal, E., Garca-Mena, J., Poggi-Varaldo,H.M., 2,4,6-Trichlorophenol and phenol removal in methanogenic

and partially aerated methanogenic conditions in a fluidized bed

bioreactor,J. Chem. Technol.Biotechnol., 80, 1180-1187 (2005).

12 Garibay-Orijel, C., Hoyo-Vadillo, C., Ponce-Noyola, M.T., Gar-ca-Mena, J., Poggi-Varaldo, H.M., Impact of long-term partial

aeration on the removal of 2,4,6-trichlorophenol in an initially

methanogenic fluidized bed bioreactor, Biotechnol. Bioeng., 94,

949-960 (2006).

13 Kargi, F., Eker, S., Uygur, A., Biological treatment of syntheticwastewater containing 2,4-dichlorophenol (DCP) in an activated

sludge unit,J.Environ.Manage., 76, 191-196 (2005).

14 Bolanos, R.M.L., Damianovic, M.H.R.Z., Zaiat, M., Foresti, E.,Assessment of the ability of sludge to degrade PCP under anaerobic

conditions,Braz.J. Chem.Eng., 22, 611-617 (2005).

15 Wase, D.A.J., Hough, J.S., Continuous culture of yeast on phenol,J. Gen.Microbiol., 42, 13-23 (1966).

16 Mrsen, A., Rehm, H.J., Degradation of phenol by a defined mixedculture immobilized by adsorption on activated carbon and sintered

glass,Appl.Microbiol.Biotechnol., 33, 206-212 (1990).

17

Denizli, A., Cihangir, N., Rad, A.Y., Taner, M., Alsancak, G., Re-moval of chlorophenols from synthetic solutions using Phanero-

chaete chrysosporium,ProcessBiochem., 39, 2025-2030 (2004).

18 Kai-Chee, L., Sudhir, R., External-loop fluidized bed airlift biore-actor (EFBAB) for the cometabolic biotransformation of

4-chlorophenol (4-cp) in the presence of phenol, Chem. Eng. Sci.,

60, 6313-6319 (2005).

19 Fialov, A., Boschke, E., Bley, T., Rapid monitoring of the biodeg-radation of phenol-like compounds by the yeast Candida maltosa

using BOD measurements,Int.Biodeter.Biodegr., 54, 69-76 (2004).

20 Zouari, H., Labat, M., Sayadi, S., Degradation of 4-chlorophenol bythe white rot fungus Phanerochaete chrysosporium in free and im-

mobilized cultures,Bioresour. Technol., 84, 145-150 (2002).

21 Ivoilov, V.S., Karasevich, I.N., Monochlorophenols as enzymessubstrates for the preparatory metabolism of phenol in Candida

tropicalis yeasts,Mikrobiologiia, 52, 956-961 (1983).

22 Krug, M., Ziegler, H., Straube, G., Degradation of phenolic com-pounds by the yeast Candida tropicalis HP 15.I, physiology ofgrowth and substrate utilization, J. BasicMicrobiol., 25, 103-110

(1985).

23 Kim, S.B., Isolation and characterization of a phenol-degradingCandida tropicalis PW-51, KoreanJ. Appl. Microbiol. Biotechnol.,

24, 743-748 (1996).

24 Jiang, Y., Wen, J.P., Li, H.M., Yang, S.L., Hu, Z.D., The biodegra-dation of phenol at high initial concentration by the yeast Candida

tropiclis,Biochem.Eng.J., 24, 243-247 (2005).

25 Jiang, Y., Wen, J.P., Jia, X.Q., Canyin, Q., Hu, Z.D., Mutation ofCandida tropicalis by irradiation with a He-Ne laser to increase its

ability to degrade phenol, Appl. Environ. Microbiol., 73, 226-231

(2007).

26 Hayde, T.G., Ploidy study in Sporothrix schenkii, Fungal Genet.Biol., 27, 49-54 (1999).

27 Zeng, F., Cui, K.Y., Fu, J.M., Sheng, G.Y., Yang, H.F., Biodegrad-ability of di (2-ethylhexyl) phthalate by Pseudomonas fluorescensFS1, Water Air Soil Poll., 140, 297-305 (2002).

28 Andrews, J.F., A mathematical model for continuous culture of mi-croorganisms utilizing inhibitory substrates, Biotechnol. Bioeng.,

10, 707-723 (1968).

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