Research in Microbiology 159 (2008) 103e109
Melanoidin-containing wastewaters induce selective laccase gene
expression in the white-rot fungus Trametes sp. I-62
Tania Gonzalez1, Marıa Carmen Terron, Susana Yague, Howard Junca2, Jose Marıa Carbajo3,
´ ´ ´ ¨ ´ ´
Ernesto Javier Zapico , Ricardo Silva , Ainhoa Arana-Cuenca , Alejandro Tellez6,
4 5 6
Aldo Enrique Gonzalez*
Department of Molecular Microbiology, Centro de Investigaciones Biologicas, Ramiro de Maeztu 9, E-28040 Madrid, Spain
Received 24 July 2007; accepted 23 October 2007
Available online 21 November 2007
Wastewaters generated from the production of ethanol from sugar cane molasses may have detrimental effects on the environment due to their
high chemical oxygen demand and dark brown color. The color is mainly associated with the presence of melanoidins, which are highly recal-
citrant to biodegradation. We report here the induction of laccases by molasses wastewaters and molasses melanoidins in the basidiomycetous
fungus Trametes sp. I-62. The time course of efﬂuent decolorization and laccase activity in the culture supernatant of the fungus were correlated.
The expression of laccase genes lcc1 and lcc2 increased as a result of the addition of complete molasses wastewater and its high molecular
weight fraction to fungal cultures. This is the ﬁrst time differential laccase gene expression has been reported to occur upon exposure of fungal
cultures to molasses wastewaters and their melanoidins.
Ó 2007 Elsevier Masson SAS. All rights reserved.
Keywords: Melanoidin; Molasses wastewaters; Laccase; Decolorization; Fungi; Ligninolytic enzymes; Basidiomycete
Final efﬂuents produced from alcoholic fermentation of
molasses are among the most environmentally harmful
* Corresponding author. Tel.: þ34 9 1837 3112x4413/4414; fax: þ34 9 1536 wastewaters generated by the sugar and byproduct industries.
0432. These efﬂuents, also known as vinasses, contain persistent toxic
E-mail address: firstname.lastname@example.org (A.E. Gonzalez).
Present address: Departamento de Microbiologıa, Instituto Cubano de los
chemicals which have a harmful impact on aquatic ecosystems,
Derivados de la Ca~a de Azucar (ICIDCA), Vıa Blanca 804 y Carretera Cen-
n not only by increasing the chemical oxygen demand (COD) but
tral, San Miguel del Padron, Havana, Cuba. also as a result of their dark brown color. This leads to a reduc-
Present address: Biodegradation Research Group e GBF, Environmental tion in penetration of sunlight in rivers, lakes and lagoons,
Microbiology, Mascheroder Weg 1 D-38124, Braunschweig, Germany. which in turn decreases oxygenation by photosynthesis and
Present address: CIFOR-INIA, Crta. de La Coru~a Km. 7, 28040 Madrid,
causes multiple damaging effects to aquatic life. The organic
Present address: Biotechnology Department, Technische Universitat ¨ matter can be degraded by conventional anaerobic-aerobic
Hamburg-Harburg, Biotechnology II, Denickestrasse, 15, 21073 Hamburg, treatments, but the colored compounds of molasses efﬂuents ap-
Germany. pear to be recalcitrant to biodegradation . The characteristic
Present address: Fac. Ciencias Forestales, Dpto. de Ingenierıa de la very dark color is mainly due to the presence of melanoidins.
Madera, Universidad de Chile, Santa Rosa, 11315 Santiago, Chile.
Present address: Departamento Biotecnologıa, Universidad Politecnic de
These brown polymers, which are formed by amino-carbonyl
Pachuca, Ex-Hacienda de Santa Barbara Km 20, Carretera Pachuca-Ciudad reactions, are widely distributed in nature and are not readily
Sahagun, Zempoala, CP. 43830, Estado de Hidalgo, Mexico. susceptible to microbial degradation.
0923-2508/$ - see front matter Ó 2007 Elsevier Masson SAS. All rights reserved.
104 T. Gonzalez et al. / Research in Microbiology 159 (2008) 103e109
Thus, there is an urgent need to develop alternative bio- 2.4. Culture conditions
technological processes to effectively remove light-absorptive
compounds from molasses efﬂuents. White-rot basidiomyce- Submerged cultures were prepared from 7-day-old cultures
tous fungi can degrade lignin and a broad range of environ- of the fungus grown on agar plates with Kirk medium .
mentally persistent xenobiotics, organopollutants and Eight plugs (1 cm2) were cut and inoculated under sterile
industrial wastewaters [18,37]. Some of these fungi have conditions in 500 ml culture ﬂasks containing 300 ml of the
also been shown to be effective in the decolorization of natu- same growth medium and four 1.5 cm diameter glass beads.
ral and synthesized melanoidins and molasses wastewaters They were incubated for 24 h at 28 C in an orbital shaker
(MWWs) . A complex non-speciﬁc enzyme system (100 rpm). A 1:10 (v/v) inoculum was transferred into 250 ml
secreted by these organisms has been shown to be associated ﬂasks containing 75 ml (total volume) of Kirk medium supple-
with their degradative capacities. The ligninolytic system mented with 20% (v/v ﬁnal concentration) of MWW. Controls
consists of two main groups of enzymes: peroxidases (lignin were prepared in the same way, except that Kirk medium was
peroxidases and manganese peroxidases) and laccases not supplemented with the wastewater. Abiotic controls con-
[1,2,11,18]. Although the enzymatic system associated with tained Kirk medium and the efﬂuent, but were not inoculated
decolorization of melanoidins appears to be related to the with fungus.
presence and activity of fungal ligninolytic mechanisms, this Fungal cultures were incubated at 28 C in an orbital shaker
relation is as yet not completely understood . (100 rpm) for 16 days. COD, decolorization, lignin peroxidase
Trametes sp. I-62 (CECT 20197) is a white-rot fungus (LiP), manganese peroxidase (MnP) and laccase activity
strain with a high detoxiﬁcation capacity towards molasses ef- measurements were monitored on a daily basis, in triplicate.
ﬂuents. It also represents a model strain for studying the diver- To study the effect of both MWW and molasses melanoi-
sity [1,13,14,20], transcriptional [21,34] and postranslational dins on lcc gene transcription, they were added to 8-day-old
regulation of laccases in a single organism. Four laccase genes fungal cultures in Kirk medium (28 C, 100 rpm) at a ﬁnal
have been reported thus far in this basidiomycete [14,20]. concentration of 0.37 mM total phenols in the culture medium.
In the present work, we analyzed the relationship between Laccase activity was monitored over a 43 h period and fresh
the production of ligninolytic enzymes and decolorization of 10 mg mycelium samples were harvested at different time
MWW by Trametes sp. I-62. The effect of molasses efﬂuents points (7, 19, 31 and 43 h) following the addition of either
and molasses melanoidins on laccase gene transcription was efﬂuent or melanoidins to the cultures.
2.5. Analytical methods
2. Materials and methods
Color units and COD were determined according to CPPA
2.1. Wastewater  and ‘‘Standard methods for the examination of water and
wastewater’’ , respectively. The concentration of total phe-
The ﬁnal efﬂuent from the distillation of ethanol produced nols was determined by the Folin-Ciocalteu method  with
from sugar-cane molasses was provided by a distillery in minor modiﬁcations  using gallic acid (Sigma Chemicals)
Havana, Cuba. MWW are complex organic mixtures including as a reference standard.
melanoidins, which results in acid dark-brown solutions. The
efﬂuent used in the present study has the following physical 2.6. Enzyme assays
characteristics: pH 4.0, color units 60,923 Æ 100, and
a COD of 55.5 Æ 1.2 g/l. Laccase activity in the culture supernatant was determined
by the method of Mansur and coworkers  using ABTS
2.2. Separation of molasses melanoidins (2,20 -azinobis-3-ethylbenzthiazoline-6-sulfonate) as the sub-
strate. Lignin and manganese peroxidases were determined
The MWW was centrifuged at 12,000 rpm for 15 min to as previously described by Tien and Kirk , and Pick and
eliminate suspended solids. The resultant supernatant was Keisare , using veratryl alcohol and phenol red, respec-
dialyzed against running tap water through a 10 kD membrane tively, as substrates. Enzyme activities were expressed in units
(Pierce) at room temperature for 2 days, and then against de- deﬁned as 1 mmol product formed per min.
ionized water for another two days. The resulting solution of
non-dialyzable compounds was used as a solution of molasses 2.7. Total RNA preparation and cDNA synthesis
RNA extraction was performed using the Fast RNA kit-Red,
2.3. Organism following the manufacturer’s instructions (BIO 101). In order to
remove contaminating DNA, 1 unit per mg of RNA of RQ1
Basidiomycete Trametes sp. I-62 (CECT 20197) was iso- DNase enzyme (Promega) was added to each RNA sample
lated from decayed wood in Pinar del Rıo, Cuba . The fun- and subsequently incubated for 30 min at 37 C. First-strand
gal culture was maintained on agar plates with Medium-7 . cDNA synthesis was carried out using 2 mg of total RNA as
Plates were grown for 7 days at 28 C and stored at 4 C. template and the cDNA synthesis kit from Roche.
T. Gonzalez et al. / Research in Microbiology 159 (2008) 103e109
2.8. Multiplex PCR reaction cultures with efﬂuent nor in the controls during the 16 days
of the experiment, under the assayed conditions. Laccase
Design and optimization of this method have been previ- was the only detectable ligninolytic activity produced under
ously described . Brieﬂy, a PCR mix was prepared by add- these conditions. Levels of this enzyme in the medium supple-
ing together the three pairs of primers used to amplify lcc1, mented with efﬂuent were always signiﬁcantly higher than
lcc2 and lcc3 (GenBank accession numbers AF548032, those of the controls (Fig. 1A). Maximal differences of 13-
AF548034, AF548035, respectively) gene fragments. A total and 19-fold were achieved in the 8- and 16-day cultures,
of 100 ml PCR mixtures also contained 5 ml of reverse tran- respectively. In contrast, decolorization of 76.9% and a COD
scription product, 2.5 U Taq polymerase (Perkin Elmer) and reduction of 71% with respect to the initial values were
all the rest of the standard components of a PCR DNA ampli- achieved at the end of the experiment (Fig. 1 and data not
ﬁcation reaction . PCR reactions were performed in shown). The time course of efﬂuent decolorization and laccase
a Rapidcycler (Idaho Technology) thermocycler. The basic activity detected in the culture supernatant of Trametes sp. I-
program comprised an initial denaturizing step at 95 C for 62 showed a similar trend. Statistical analysis revealed a signif-
1 min followed by 30 cycles of 95 C for 45 s, 30 s at the icant correlation of 96% between the two variables.
annealing temperature (59 C) and 72 C for 2 min, one ﬁnal
extension step at 72 C for 7 min and incubation at 4 C until 3.2. Effect of MWW and of molasses melanoidins on
further storage of reactions at À20 C. The same procedure laccase gene transcription
was performed to amplify a fragment of the constitutively
expressed glyceraldehyde-3-phosphate dehydrogenase gene The effect of complete MWW and of the high molecular
( gpd1, GenBank acc. No. AF297874) from the RT reaction, weight fraction (corresponding to melanoidins) upon induction
which was used as a control to normalize differences in the to- of laccase gene expression was compared. The time course
tal RNA input or in the reverse transcription reaction efﬁcien- analysis of laccase activity (Fig. 1B) indicated that 30 min
cies. The only changes were that ampliﬁcation was performed after their addition, both the complete efﬂuent and the isolated
for 25 cycles and the annealing temperature was set at 55 C. molasses melanoidins caused an increase in extracellular lac-
case activity. Although the time course was very similar, the
2.9. Quantitative and statistical analysis maximal level of activity was slightly higher and more rapidly
achieved (after 11 h) in the presence of the melanoidin fraction
Three independent ampliﬁcation reactions were performed with respect to those media amended with complete MWW, in
for each condition assayed. PCR products (10 ml of each reac- which maximal levels were detected after 24 h. Laccase activ-
tion) were separated by 1.5% agarose gel electrophoresis and ity was minimal in controls, and no signiﬁcant changes were
visualized after staining for 10 min in a 1 mg/ml ethidium produced in these samples during the assay.
bromide solution. Densitometric analysis of Polaroid ﬁlm gel Both complete molasses efﬂuents and melanoidins selec-
images was performed using ‘‘Image Quant 3.3’’ software tively induced lcc1 and lcc2 laccase gene transcription (Figs.
(Molecular Dynamics). Levels of lcc mRNAs were expressed 1C and 2A,B). However, a higher increase in lcc transcript
in arbitrary units, as the rate between lcc transcript levels levels was observed in the presence of the complete molasses
(previously normalized according to size differences) and efﬂuent, with induction being detected from the ﬁrst sampling
those of gpd1 calculated by the following equation: laccase/ time (30 min) after the addition of the efﬂuent. In contrast, at
( gpd1sample/gpd1average). For all experiments and determi- that time no lcc gene expression could be detected in the media
nations, variability coefﬁcients between triplicate samples supplemented only with the molasses melanoidins. Maximal
were calculated. Statistical differences were determined by induction of lcc1 transcripts was detected 7 h after supplemen-
the ‘‘t test’’ for mean comparison (with P 0.001). tation with melanoidins and at 19 h following addition of the
complete molasses efﬂuent. In terms of lcc2 transcript levels,
3. Results maximal expression of lcc2 was observed 7 h after the addition
of both molasses efﬂuent and melanoidins. However, no lcc3
3.1. Ligninolytic enzyme proﬁle and gene expression could be detected in any of the samples.
MWW decolorization When the time course of total transcripts was analyzed
(Fig. 2C), it could be noted that the highest lcc levels were ob-
In a previous study we reported the optimization of differ- served 7 h after the addition of both MWW and melanoidins.
ent parameters in submerged cultures of Trametes sp. I-62 in However, overall induction of lcc gene expression was initially
order to attain the maximum reduction in color and COD of produced in the presence of the complete MWW and was
the MWW . slightly higher than induction observed with the isolated mel-
These optimal parameters were applied here to analyze the anoidins. Nevertheless, the later decrease, after 19 h, was more
relationship between the production of ligninolytic enzymes pronounced in the presence of the complete MWW; indeed,
and efﬂuent decolorization. We monitored culture supernatant after 31 h, laccase levels were lower than those corresponding
for the presence of both lignin peroxidase (LiP) and manga- to addition of the melanoidins. No lcc gene expression were
nese peroxidase (MnP) activity as well as for laccase activity. detected in any of the control samples throughout the course
Neither LiP nor MnP activities could be detected in the of the experiment.
106 T. Gonzalez et al. / Research in Microbiology 159 (2008) 103e109
1 100 . Those studies were reviewed by Coulibaly and coworkers
A vinasse lac. act.  and by Pant and coworkers . The results in our work
control lac. act.
0,8 80 compare with some of the best results reported in relation to
the extent of decolorization and COD removal. Paradoxically,
Lac. Act. (U/ml)
the ﬁrst studies on the enzymatic system involved in these
processes did not focus on ligninolytic enzymes. In fact, intra-
cellular sugar oxidase enzymes were considered as having the
0,4 40 most important role in decolorization . Miyata and
coworkers  subsequently proposed the participation of lig-
0,2 20 ninolytic enzymes, particularly peroxidases, in the degradation
In the present work, MnP and LiP do not appear to be in-
2 4 6 8 10 12 14 16 volved in decolorization of MWW by Trametes sp. I-62, since
days neither of these enzymatic activities could be detected under
conditions that resulted in maximal color reduction. Laccase
was the only enzyme which could be detected at high levels
B in culture supernatants. Previous studies to detect ligninolytic
enzymes in this fungus showed that the major ligninolytic ac-
tivity in culture supernatants of Trametes I-62 was laccase, in
conjunction with small amounts of manganese peroxidase
Lac. Act. (U/ml)
0,024 . No lignin peroxidase has been detected thus far in this
strain, even in culture conditions that permit the expression
of this enzyme in a Trametes versicolor strain used as a control
melanoidin fraction (data not published). A study on decolorization of colored ef-
complete MWW ﬂuents from textile, paper and pulp mill and distillery waste
with a marine basidiomicetous fungus has been recently pub-
0,006 lished by D’Souza and coworkers . The authors also report
laccase as being the dominant lignin-degrading enzyme, with
very low activities of manganese-dependent peroxidase and no
0 6 12 18 24 30 36 42 lignin peroxidase activity.
h Although induction of laccase activity in various basidio-
mycete grown on MWW has previously been reported
[12,15] no clear correlation with efﬂuent decolorization was
0 0,5 7 19 31 43 0 0,5 7 19 31 43 h ´
observed. More recently, Rodrıguez and coworkers  sug-
gested an important role for laccases from Pleurotus ostreatus
lcc2 – in MWW decolorization, as well as the involvement of other
enzymes or mechanisms when nutrient levels become restric-
tive. On the other hand, D’Souza and co-workers  de-
lcc2 – scribed induction of laccase activity by MWW and
decolorization of the efﬂuent with a partially puriﬁed laccase
preparation. Results presented here strengthen the role of lac-
lcc2 – cases in MWW color reduction, since decolorization corre-
lcc3 – lated directly with laccase activity throughout the experiment.
Fig. 1. Effect of MWW and molasses melanoidins on Trametes sp. I-62 laccase Recent works have focused on the use of different natural
activity and lcc transcript levels. (A) Biotreatment with the fungus grown in or synthetic compounds to induce laccases and to improve
Kirk medium with 20% vinasses for 16 days. Laccase activity in cultures their secretion by white-rot fungi [3,15,22], but fewer have
with efﬂuent and corresponding decolorization rate values are represented. determined the inductive effect of these compounds on the
Controls were grown on Kirk medium without efﬂuent. (B) Changes in laccase
activity after the addition of the complete MWW or the melanoidin fraction to
expression of laccase genes [5,6,32]. Previous work by our
8-day cultures of Trametes sp. I-62 in Kirk medium. (C) Effect on lcc tran- group has shown that lcc gene expression in Trametes sp. I-
script levels. Ampliﬁcation of a fragment from the gpd1 gene was used as 62 is induced by veratryl alcohol, by two of its isomers and
an internal control for each sample. by different aromatic monomers [13,21,34]. We now report
for the ﬁrst time that lcc gene expression in this fungus can
4. Discussion also be induced by MWW and by molasses melanoidins.
Maximal levels of lcc transcripts were detected in the
The application of basidiomycetous fungi to melanoidin de- presence of the complete and the high molecular weight frac-
colorization has been studied for more than 30 years. Various tion of the efﬂuent, and they were similar to those observed
strains can degrade these polymers and decolorize MWW following induction of the best aromatic monomers tested
T. Gonzalez et al. / Research in Microbiology 159 (2008) 103e109
thus far ( p-coumaric acid, guaiacol and p-methoxyphenol)
under identical culture conditions in Trametes sp. I-62 .
Nevertheless, both the complete MWW and the dialyzed frac-
A 30 tion resulted in a more rapid increase in laccase activity than
those obtained with aromatic monomers in the previous study.
25 lcc2 On the other hand, it would seem contradictory that maximal
lcc3 extracellular laccase levels occurred ﬁrst in the presence of the
isolated melanoidins, even when lcc genes were previously
induced by the complete MWW. Various factors would explain
these phenomena, considering that the effect of the efﬂuent on
laccase activity can occur at a number of different levels to
produce more active protein. For instance, it has been reported
10 that humic acids possess surfactant properties, which have
been proposed to favor the liberation of enzymes in Trametes
5 versicolor and Phanerochaete chrysosporium . Thus, due to
the structural similarity between humic acids and melanoidins,
it seems reasonable to suggest that melanoidins play a similar
0 6 12 18 24 30 36 42 role, resulting in increased release of enzymes from fungus
Time (h) grown on cultures amended by these compounds. In addition,
melanoidins, as a result of the presence of phenolic groups in
their structure, may also act as laccase stabilizers. Indeed, Mai
and coworkers  reported enhancement of laccase stability
lcc1 in the presence of phenolics compounds. Prior to the addition
25 lcc2 of the efﬂuent to Trametes sp. I-62 cultures, low levels of ex-
tracellular laccase were measured. If both the afore mentioned
20 factors are considered, namely stimulation of laccase secretion
from the fungus coupled with potential stabilization of the
15 enzyme in culture media, then the more marked increment
in laccase activity observed in media with isolated melanoi-
dins, which occurs even before detection of lcc gene induction,
can be explained.
The rapid induction of lcc genes in media with complete
molasses efﬂuent may be associated with the presence of
low molecular weight compounds that can be easily trans-
0 ported through fungal membranes. The inductive effect of
0 6 12 18 24 30 36 42 melanoidins at the genetic level may, in fact, be mediated by
Time (h) the action of lower molecular weight compounds derived
60 from their degradation. Another factor to consider is that mel-
C anoidins are potent copper chelators. It has been shown that
complete MWW their chromophore groups are related to this property, since
liberation of chelated copper was detected when melanoidin
degradation occurs as part of the decolorization process .
40 If we consider that laccase genes can be induced by copper
[25,32], then degradation of melanoidins could result in induc-
tion of lcc gene expression as a consequence of the release of
copper into the culture media. These are tentative explanations
which require additional studies for conﬁrmation.
Fig. 2. Changes in the relative transcript levels of lcc1, lcc2 and lcc3 at differ-
ent times following addition of the complete MWW (A), and of the melanoidin
fraction (B) to 8-day old cultures in Kirk medium analyzed by multiplex RT-
PCR. Each data point represents the mean PCR product yield from two inde-
pendent ampliﬁcations. Arbitrary units express the ratio between lcc transcript
0 6 12 18 24 30 36 42
levels (normalized according to PCR product size) and those of glyceralde-
hyde 3-phosphate dehydrogenase ( gpd1). This means: laccase/( gpd1sample/
gpd1average). (C) Total lcc transcript levels calculated from the addition of
the relative levels of lcc1, lcc2 and lcc3 mRNA in each sample, at different
times, following addition of the complete MWW or the melanoidin fraction.
108 T. Gonzalez et al. / Research in Microbiology 159 (2008) 103e109
In conclusion, results presented in this work indicate a close role in biological systems Vol. 37 (pp. 559e586). New York: Marcel
relationship between decolorization of MWW and selective Dekker.
 ´ ´
Gonzalez, T., Terron, M.C., Yague, S., Zapico, E., Galletti, G.C.,
induction of laccase activity in Trametes sp. I-62. Two laccase ´
Gonzalez, A.E. (2000) Pyrolysis/gas chromatography/mass spectrometry
genes, lcc1 and lcc2, are overexpressed during the decoloriza- monitoring of fungal-biotreated distillery wastewater using Trametes sp.
tion process. Differential laccase gene expression occurs upon I-62 (CECT 20197). Rapid Comm. Mass Spectrom 14, 1417e1424.
exposure of fungal cultures to both molasses wastewaters and  ´ ´ ´
Gonzalez, T., Terron, M.C., Zapico, E., Tellez, A., Yague, S., ¨
their melanoidins, the high molecular weight fraction of these Carbajo, J.M., et al. (2003) Use of multiplex reverse transcription-pcr
to study the expression of a laccase gene familiy in a basidiomycetous
efﬂuents. These ﬁndings could have important implications for fungus. Appl. Environ. Microbiol. 69, 7083e7090.
a better understanding of molecular processes involved in  ´ ´ ´
Gonzalez, T., Terron, M.C., Zapico, E., Yague, S., Tellez, A., Junca, H.,
depollution of distillery industrial efﬂuents. et al. (2003) Identiﬁcation of a new laccase gene and conﬁrmation of
genomics predictions by cDNA sequences of Trametes sp. I-62 laccase
family. Mycol. Res. 107, 727e735.
Acknowledgments  Kahraman, S., Gurdal, I. (2002) Effect of synthetic and natural culture
media on laccase production by white rot fungi. Biores. Technol. 82,
We are grateful to G. del Solar, M. Espinosa and A. Dobson
 Kahraman, S., Yesilada, O. (2003) Decolorization and bioremediation of
for their critical reading of the manuscript. We also molasses wastewater by white-rot fungi in semi-solid-state condition.
acknowledge the valuable help of L. Rodon and F.J. Carbajo Folia Microbiol. 48, 525e528.
with some of the ﬁgures.  Kirk, T.K., Croan, K.S., Tien, M., Murtagh, K.E., Farrell, R.L. (1986)
This work was supported by projects BIO95-2065-E and Production of multiple ligninases by Phanerochaete chrysosporium:
´ effect of selected growth conditions and use of a mutant strain. Enz.
BIO97-0655 from the Comision Interministerial de Ciencia
Microbiol. Technol. 8, 27e32.
y Tecnologıa (CICYT, Madrid, Spain). T. Gonzalez acknowl-  Leonowicz, A., Matuszewska, A., Luterek, J., Ziegenhagen, D., Wojta- s
edges support from a Mutis Program doctoral grant from Wasilewska, M., Cho, N.-S., et al. (1999) Biodegradation of Lignin by
AECI (Spain) as well as from The International Foundation White Rot Fungi. Fungal Genet. Biol. 27, 175e185.
for Science (grant F/3899-1). M.C. Terron acknowledges  Mai, C., Schormann, W., Milstein, O., Huttermann, A. (2000) Enhanced
´ ´ stability of laccase in the presence of phenolic compounds. Appl.
a post-doctoral grant from the Consejerıa de Educacion y
Microbiol. Biotechnol. 54, 510e514.
Cultura de la Comunidad Autonoma de Madrid (Spain).  ´ ´
Mansur, M., Suarez, T., Fernandez-Larrea, J.B., Brizuela, M.A.,
Gonzalez, A.E. (1997) Identiﬁcation of a laccase gene family in the
new lignin-degrading basidiomycete CECT 20197. Appl. Environ.
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