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International Journal of Medicinal Mushrooms, 17(1): 77–86 (2015)
77
1045-4403/15/$35.00 © 2015 Begell House, Inc. www.begellhouse.com
Shiitake Medicinal Mushroom, Lentinus edodes
(Higher Basidiomycetes) Productivity and
Lignocellulolytic Enzyme Proles during Wheat Straw
and Tree Leaf Bioconversion
Vladimir Elisashvili,* Eva Kachlishvili, & Mikheil Asatiani
Agricultural University of Georgia, University Campus at Digomi, Tbilisi, Georgia
*Address all correspondence to: Vladimir Elisashvili, Agricultural University of Georgia, University Campus at Digomi, 13 km David
Agmashenebeli Alley, 0159 Tbilisi, Georgia; v.elisashvili@agruni.edu.ge
ABSTRACT: Two commercial strains of Lentinus edodes have been comparatively evaluated for their productivity
and lignocellulolytic enzyme proles in mushroom cultivation using wheat straw or tree leaves as the growth
substrates. Both substrates are protable for recycling into shiitake fruit bodies. L. edodes 3715 gave the lowest yield
of mushroom during tree leaves bioconversion with the biological efciency (BE) 74.8% while the L. edodes 3721
BE achieved 83.4%. Cultivation of shiitake on wheat straw, especially in the presence of additional nitrogen source,
increased the L. edodes 3721 BE to 92-95.3% owing to the high hydrolases activity and favorable conditions. Despite
the quantitative variations, each strain of L. edodes had a similar pattern for secreting enzymes into the wheat straw
and tree leaves. The mushrooms laccase and MnP activities were high during substrate colonization and declined
rapidly during primordia appearance and fruit body development. While oxidase activity decreased, during the same
period cellulases and xylanase activity raised sharply. Both cellulase and xylanase activity peaked at the mature fruit
body stage. When mushrooms again shifted to the vegetative growth, oxidase activity gradually increased, whereas
the hydrolases activity dropped rapidly. The MnP, CMCase, and FP activities of L. edodes 3721 during cultivation on
wheat straw were higher than those during mushroom growth on tree leaves whereas the laccase activity was rather
higher in fermentation of tree leaves. Enrichment of wheat straw with an additional nitrogen source rather favored to
laccase, MnP, and FPA secretion during the vegetative stage of the L. edodes 3721 growth.
KEY WORDS: medicinal mushrooms, Lentinus edodes, fruit body, biological efciency, wheat straw, tree leaves,
lignocellulolytic enzymes
ABBREVIATIONS: ABTS, 2,2′-azino-bis-[3-ethyltiazoline-6-sulfonate]; BE, biological efciency; CMCase, car-
boxymethyl cellulase; FB, mature fruit bodies stage; FPA , lter paper activity; MEA, malt extract agar; MnP, man-
ganese-dependent peroxidase; P, primordia formation stage; PH, postharvest stage; SC, substrate colonization stage
I. INTRODUCTION
Mushrooms have recently received increasing atten-
tion from researchers in food and pharmaceuticals.
Many species have long been used in traditional
medicines or functional foods in China, Japan, and
other Asian countries. Nowadays there is an increas-
ing public interest in the secondary metabolites from
mushrooms for discovering new drugs or lead com-
pounds. A number of bioactive constituents have
been isolated from mushrooms, including small
molecule compounds, polysaccharides, proteins,
and their complexes with antioxidant, antitumor,
antiviral, antimicrobial, and immunomodulatory
agents.1–3
Shiitake medicinal mushroom, Lentinus edodes
(Berk.) Singer (Marasmiaceae, higher Basidiomy-
cetes) is a xylotropic species. It is one of the most
precious edible species, which can be used as both
food and medicine. The L. edodes mushroom is
gradually attracting attention for its high nutrient
value and health-improving functions. The shiitake
mushroom has served as a model for investigating
functional fungi properties and isolating pure com-
pounds for pharmaceutical use. It is a rich source of
proteins, carbohydrates, fiber, vitamins, and miner-
International Journal of Medicinal Mushrooms
Elisashvili, Kachlishvili, & Asatiani
78
als. L. edodes is revered in medicine for its health-
promoting effects, including antiviral, antifungal,
antioxidant, and antitumor effects that boost the
immune system; it lowers cholesterol, works as an
anticoagulant, and is helpful in cancer treatment.4,5
This mushroom is cultivated on both natu-
ral and articial logs since this white rot fungus
is able to colonize different types of agricultural
wastes as growth substrates, although exploitation
of the substrate varies with the species, strain, and
cultivation technology. In particular, the use of
sawdust-based cultivation to replace natural logs
has contributed to expanding the production and
consumption of L. edodes. The main advantages of
this method are the short time to complete a crop
cycle and the higher yields.6 In recent years, wheat
straw and other agricultural wastes have been ex-
amined instead of sawdust for mushroom cultiva-
tion.7–10 However, in spite of the commercial sig-
nicance of L. edodes, little is known concerning
the mushroom performance on different substrates,
especially regarding mushroom yield and quality.
In particular, very little attention has been given
to the evaluation of the lignocellulolytic enzymes
activity participating in deconstruction of plant
substrates. Available data indicate that L. edodes
produces an array of hydrolases and oxidases for
bioconversion of lignocellulosic materials and the
expression of these enzymes activity is related to
and dependent on medium composition, especially
on the growth substrate.8,9,11–14 However, compared
with other cultivated mushrooms, very little is
known about the nature and prole of the ligno-
cellulolytic enzymes secreted by L. edodes during
substrate colonization and fruit body development.
Few studies indicate that gene expression of these
enzymes is strongly regulated during fruit body
development.9,14 Apart from the fundamental sig-
nicance, the understanding of the physiological
mechanisms regulating enzyme synthesis in ligno-
cellulose bioconversion and mushroom morpho-
genesis is important to predict fruiting cycles, to
increase efciency of substrate utilization, and to
contribute to commercial mushroom production
for use as food and medicine. Therefore, the aim of
the present study was to determine the relationship
between the proles of lignocellulolytic enzymes
production and the life cycle of two commercial
strains of L. edodes. Moreover, the impact of two
growth substrates (wheat straw and tree leaves) on
the mushroom yield and extracellular enzyme ac-
tivity was also evaluated in this work.
II. MATERIALS AND METHODS
A. Organisms and Spawn Preparation
The mother cultures of L. edodes (strains 3715
and 3721) were purchased from the Mycelia Com-
pany (Gent, Belgium) and maintained on malt ex-
tract agar (MEA) at 4oC. To prepare spawn, wheat
grains cooked in tap water and mixed with 20 g
CaCO3/kg were lled in 750-mL asks and steril-
ized at 121°C for 1 h. After cooling, the asks were
inoculated with small pieces of mycelial agar and
cultivated at 25°C in the dark.
B. Materials and Cultivation Conditions
Wheat straw (from the Kakheti region) shredded
into pieces of 1–5 cm in length and leaves of Fagus
orientalis (collected in the Sabaduri forest) were
used as the mushroom growth substrates. Both ma-
terials were soaked in tap water or tap water–based
synthetic medium containing 3 g/L (NH4)2SO4 and
5 g/L yeast extract for 16 h at room temperature.
After leaching, 1 kg of the substrate was placed
in polypropylene gas-permeable bags Microsac
PPB75/BEU6/X33-57 (SACO2, EKE, Belgium)
for sterilization by autoclaving at 121°C for 1 h.
After cooling, the bags were inoculated with 10%
(wet weight) of evenly distributed spawn. Inocu-
lated bags (four replicates for each strain/sub-
strate) were incubated in the dark at 24°C. After
2 mo of incubation, the bags were exposed during
3 d at 4°C to experience a cold shock necessary for
the stimulation of fructication. Then the blocks
were kept in the fruiting room at 15°C, with rela-
tive humidity around 90%, and under illumination
of about 400 lux. When the rst primordia signs
appeared, the bags were removed from the blocks.
After the second ush, blocks were soaked in tap
Volume 17, Number 1, 2015
Lentinus edodes Productivity and Lignocellulolytic Enzyme Proles during Wheat Straw and Tree Leaf Bioconversion 79
water (12–15oC) for 18 h and transferred back to
the fruiting room.
During the shiitake cultivation, samples (1–2 g
dry weight) were taken with a spatula from ve
different regions of blocks surface (7–10 mm in
depth) at various stages of the mushroom devel-
opment: substrate colonization stage (SC, 5–7 d
before fruiting), primordial (P) stage, mature fruit
bodies (FB) stage, and 5–7 d after harvesting of
fruit bodies (PH). Distilled water was added to the
fresh material twice (2 × 25 mL) and extracellular
enzymes were extracted by agitation for 3 min. The
solids were separated by centrifugation at 6000 ×
g for 20 min and dried at 60°C; resulting superna-
tants were used to measure pH, sugar content, and
enzyme activity.
C. Biological Efciency
Biological efciency (BE) was estimated as the
ratio of the weight of fresh fruiting bodies and
weight of dry substrate, multiplied by 100.
D. Analytical Methods
The total cellulase activity (lter paper activity
[FPA]) and the carboxymethyl cellulase (CMCase)
were assayed according to International Union of
Pure and Applied Chemistry recommendations by
using, respectively, a strip of lter paper (What-
man no. 1) and CMC low viscosity (1% w/v) in
50 mM citrate buffer (pH 5.0) as the substrates.15
Xylanase activity was determined by incubation of
properly diluted sample birch wood xylan (Roth
7500) (1% w/v) in 50 mM citrate buffer (pH 5.0)
at 50oC for 10 min.16 In all assays, the release of re-
ducing sugars was measured using dinitrosalicylic
acid reagent.17 Glucose and xylose standard curves
were used to calculate the cellulase and xylanase
activities. One unit of cellulase and xylanase activ-
ity was dened as the amount of enzyme, releas-
ing 1 µmol of glucose or xylose, respectively, per
minute.
Laccase activity was determined by monitor-
ing the A420 change related to the rate of oxidation
of 1 mM 2,2′-azino-bis-[3-ethyltiazoline-6-sul-
fonate] (ABTS) in 50 mM Na-acetate buffer (pH
3.7).18 Assays were performed at 20 ± 1oC with
50 µL of adequately diluted culture liquid. MnP ac-
tivity was measured by oxidation of Phenol Red.19
One-milliliter reaction mixtures were incubated
for 1–5 min at 20 ± 1°C in the presence of 0.1 mM
H2O2. The reaction was terminated with 50 µL 4 M
NaOH and absorbance was read at 610 nm. One
unit of laccase and MnP activity was expressed as
the amount of enzyme required to oxidize 1 µmol
of ABTS or Phenol Red in 1 min. Activities in the
absence of H2O2 were subtracted from the values
obtained in the presence of hydrogen peroxide
to establish true peroxidase activity. Activity of
CMCase, xylanase, FPA, laccase, and MnP are
presented as units per gram of dry substrate.
III. RESULTS
A. Productivity
In this study, two strains of L. edodes have been
comparatively evaluated for their productivity in
mushroom cultivation using wheat straw or tree
leaves as the growth substrates. The mushroom
spawn run and the substrate colonization proceed-
ed quickly with formation of the whitish mycelia
on the surface and inside of the blocks. Depending
on the mushroom strain and growth substrate, all
blocks were completely colonized after 24–29 d of
shiitake growth. Primordia and then fruiting bodies
appeared after 66–67 d and 70–72 d of L. edodes
3721 and L. edodes 3715 cultivation, respectively.
That is, earliness (time elapsed between the day
of inoculation and the day of the rst primordia
appearance) was rather dependent on mushroom
strain.
Cultivation of both strains on the same tree
leaves/tap water substrate showed that the mush-
room yield was strain dependent (Table 1). L.
edodes 3721 appeared to be more productive com-
pared with L. edodes 3715, especially during the
rst ush; the mushrooms’ BE achieved 83.4%
and 74.8%, respectively. The comparison of L.
edodes 3721 growth on two different substrates
International Journal of Medicinal Mushrooms
Elisashvili, Kachlishvili, & Asatiani
80
(tree leaves and wheat straw) indicates that the ce-
real substrate ensured higher yield of mushroom
fruiting bodies during the entire period of shiitake
cultivation. Moreover, the BE of L. edodes 3721
grown on the wheat straw was 8.6% higher than
that in tree leaf bioconversion. Finally, the data
obtained prove that soaking of both substrates
by tap water is sufcient to receive a high yield
of shiitake mushroom. However, the soaking of
wheat straw by nutrient medium containing ni-
trogen source and yeast extract caused the further
increase of mushroom fruiting bodies yield from
92% to 95.3%.
B. Enzyme Activity during Development of
L. edodes 3715
Evaluation of L. edodes 3715 cellulase and xy-
lanase activity permitted us to establish that three
tested enzyme activities correlated during mush-
room development on tree leaves (Fig. 1). Xyla-
nase activity of mushroom was approximately 2–3
times higher than that of endoglucanase. During
substrate colonization (stage SC), L. edodes 3715
secreted comparatively low CMCase, xylanase,
and FP activities. At the stage of primordia ap-
pearance (stage P), extracellular activity of these
enzymes sharply increased and attained the maxi-
mum level at the period of mature fruiting body
formation (stage FB). After renewing of vegeta-
tive phase (stage PH), CMCase, FP, and especially
xylanase activity signicantly decreased. No MnP
was detected during the shiitake development on
tree leaves as the growth substrate. The proles of
laccase activity signicantly contrasted with that
of hydrolases. The data presented in Fig. 1 show
that at the end of substrate colonization (stage SC),
laccase activity reached 9.9 U/g substrate. At the
moment of primordia appearance (stage P), laccase
activity was equal to 8.3 U/g and sharply decreased
to 0.7 U/g during fruiting body maturation. Six
days after the harvest, when the vegetative phase
(stage PH) was renewed, the laccase activity again
increased and reached 8.6 U/g substrate.
C. Enzyme Activity during Development
of L. edodes 3721
When L. edodes 3721 was cultivated on tree leaves
as the shiitake growth substrate, the same regulari-
ties were revealed in hydrolase activities measure-
ment (Fig. 2). The transition of culture from the
vegetative phase of development to primordia for-
mation and then to fruit bodies maturation was ac-
companied by a signicant increase in endogluca-
nase, xylanase, and FP activity. During this period,
the CMCase and xylanase activities of mushroom
culture increased more than 6- and 3-fold, respec-
tively. The total cellulase activity of L. edodes
3721 increased with a lesser extent (approximately
2-fold). At the same time, an almost 10-fold de-
crease of L. edodes 3721 laccase activity was ob-
served during the same period of culture develop-
ment. In contrast with L. edodes 3715, mushroom
strain 3721 was capable of secreting MnP in tree
leaf bioconversion, accumulating 5.3 U/g at the
end of substrate colonization. By the primordia ap-
pearance time, the enzyme activity decreased and
completely disappeared at the FB stage. When the
culture again was in the vegetative phase of de-
TABLE 1: L. edodes Fruiting Bodies Yield and BE Tree Leaves and Wheat Straw
Bioconversion
Mushroom strain,
substrate/moistener
Fruiting bodies yield, g
BE, %Flush I Flush II Flush III Total
L. edodes 3715, leaves/water 435 210 103 748 74.8
L. edodes 3721, leaves/water 501 225 108 834 83.4
L. edodes 3721, straw/water 564 236 120 920 92.0
L. edodes 3721, straw/medium 550 257 146 953 95.3
Volume 17, Number 1, 2015
Lentinus edodes Productivity and Lignocellulolytic Enzyme Proles during Wheat Straw and Tree Leaf Bioconversion 81
FIG. 1: L. edodes 3715 CMCase, xylanase, FPA, MnP, and laccase activities in development on the tree leaves
soaked with tap water
FIG. 2: L. edodes 3721 CMCase, xylanase, FPA, MnP, and laccase activities in development on the tree leaves
soaked with tap water
International Journal of Medicinal Mushrooms
Elisashvili, Kachlishvili, & Asatiani
82
velopment (7 d after harvesting of fruit bodies), L.
edodes 3721 cellulase and xylanase activities de-
creased two times, whereas mushroom laccase and
manganese peroxidase activities sharply increased
up to 13.6 U/g and 8.2 U/g substrate, respectively.
It is worth noting that the activities of all tested
lignocellulolytic enzymes during the PH stage
appeared to be much higher than those in the SC
stage.
The substitution of tree leaves as growth sub-
strate for L. edodes 3721 cultivation by wheat
straw soaked in tap water did not change the pro-
les of hydrolase and oxidase activities accumula-
tion. However, the data represented in Fig. 3 show
that the shiitake cultivation on wheat straw favored
endoglucanase, xylanase, and FP activities secre-
tion, especially during substrate colonization and
primordia formation phases. Concerning the lig-
ninolytic enzymes, L. edodes 3721 MnP activity
in mushroom cultivation on straw appeared to be
especially high exceeding the same enzyme activ-
ity during growth on tree leaves more than 5–13
times. It is interesting that the laccase activity in
mushroom growth on wheat straw did not decrease
after termination of vegetative growth (i.e., during
primordia formation). Nevertheless, at the stage of
matured fruiting bodies, laccase activity sharply
decreased; after 7 d after fruit bodies harvesting,
it again increased like in other mushroom cultures.
The study of L. edodes 3721 enzymatic ac-
tivity proles in bioconversion of wheat straw
soaked in tap water supplemented with ammonium
sulphate and yeast extract showed practically the
same regularities as in development on substrate
without supplements. As seen in Fig. 4, laccase
and MnP activities reached a peak during the colo-
nization phase when the substrate was fully colo-
nized. Enzyme levels decreased sharply through-
out the primordia developmental stages, reaching
the lowest levels during the fruit body maturation.
At the same time, the shift from vegetative growth
to fruit body development was related to the in-
crease of polysaccharide-hydrolyzing enzyme
secretion. Comparison of the mushroom culture
behavior during development on the enriched and
nonsupplemented substrates shows that during the
vegetative stage of the mushrooms growth on the
former substrate, the activities of laccase, MnP,
FIG. 3: L. edodes 3721 CMCase, xylanase, FPA, MnP, and laccase activities in development on the wheat straw
soaked with tap water
Volume 17, Number 1, 2015
Lentinus edodes Productivity and Lignocellulolytic Enzyme Proles during Wheat Straw and Tree Leaf Bioconversion 83
and FP were evidently higher compared with those
on the last substrate. High hydrolase activities se-
cretion, especially the total cellulase activity, was
observed during the subsequent stages of shiitake
cultivation on the substrate enriched with nitrogen
and vitamins. It is worth also noting that in contrast
with previous cultures, MnP did not disappear dur-
ing the FB stage in cultivation of L. edodes 3721
on the enriched substrate.
IV. DISCUSSION
In this study, the BE and the proles of lignocel-
lulolytic enzyme accumulation in bioconversion of
tree leaves by two commercial strains of L. edodes
have been evaluated for the rst time. They were
compared with those in the shiitake development
process on wheat straw. As shown in Figs. 1–4,
colonization and the mushroom morphogenesis
process of both substrates are related to the par-
ticular biochemical changes. Signicant uctua-
tions in hydrolytic and oxidative enzyme activities
were observed in various stages of the shiitake life
cycle. Despite the quantitative variations, each
strain of L. edodes had a similar pattern for secret-
ing enzymes into the wheat straw and tree leaves.
Independently of the L. edodes strain and growth
substrate used, the mushroom laccase and MnP
activities were high during substrate colonization
and declined rapidly during primordia appearance
and fruit body development. While oxidase activi-
ty decreased, cellulase and xylanase activity raised
sharply during the same period. Both cellulase and
xylanase activity peaked at the mature fruit body
stage. When mushrooms again shifted to the vege-
tative growth, oxidase activity gradually increased,
whereas the hydrolase activity dropped rapidly.
These results show that changes in the concen-
tration of lignocellulose-deconstructing enzymes
are associated with the fruiting process. Similar
changes in hydrolase and oxidase activity during
the mushrooms’ life cycle were reported for Agari-
cus bisporus,20 Pleurotus strains,21–23 as well as for
L. edodes.8,14 However, during Volvariella volva-
cea development, laccase activity increased after
vegetative growth and stayed high until the fruiting
bodies matured.22 It is interesting to note that in a
study of sawdust-based culture of L. edodes, gene
FIG. 4: L. edodes 3721 CMCase, xylanase, FPA, MnP, and laccase activities in development on the wheat straw
supplemented with nitrogen source
International Journal of Medicinal Mushrooms
Elisashvili, Kachlishvili, & Asatiani
84
expression for laccase and cellulase correlated di-
rectly with the level of enzyme activity (i.e., the
level of laccase transcripts was maximal during the
mycelial growth stage, and then declined rapidly at
the fruiting stage).14 By contrast, the cellulase tran-
script level peaked during fruit body development.
Efcient colonization and utilization of growth
substrate, and consequently the mushroom pro-
ductivity, depend on the capability of mushroom
to synthesis required extracellular hydrolytic and
oxidative enzymes degrading the main polymers
of substrate, cellulose, hemicelluloses, and lignin.
From our results and data available in the litera-
ture, it is reasonable to assume that the high lac-
case and MnP activity during mushroom vegeta-
tive growth provides breakdown of the lignin to
open access of hydrolases to polysaccharides.
The decrease and even inactivation of ligninolytic
activity at the onset of fruiting may be related to
the proteolysis of oxidases and redirection of con-
structive material for carpophore formation. The
sharp increase of hydrolase activity during the P
and FB stages is important to accelerate cellulose
and hemicellulose hydrolysis to steadily supply the
mushroom with new carbon and energy resources.
Mata and Savoie8 clearly showed that the maxima
of carbohydrase activity in L. edodes development
were actually related to a signicant increase in
metabolic activity.
Evaluation of mushroom enzyme activity did
not reveal signicant qualitative differences in lac-
case, CMCase, and xylanase expression in biocon-
version of the same substrate (tree leaves) by two
tested strains. Nevertheless, the FPA of L. edodes
3715 was 2- to 3-fold higher than that of L. edodes
3721 during the entire cultivation period. A ma-
jor distinguishing feature of L. edodes 3715 was
the incapability of this strain to produce MnP in
colonization of tree leaves. Moreover, this study
showed that the level of the tested enzyme activity
depends on the substrate used. The role of the vari-
ous substrates on edible mushroom growth, BE,
and enzyme activity was proven in recent stud-
ies.6–10,13,23 The data presented in Figs. 2 and 3 show
that the levels of MnP, CMCase, and FP activities
of L. edodes 3721 during mushroom cultivation on
wheat straw were higher than those during fungus
growth on tree leaves, whereas the fungus laccase
activity was rather higher in fermentation of tree
leaves. Enrichment of wheat straw with an addi-
tional nitrogen source rather favored laccase, MnP,
and FPA secretion during the vegetative stage of
L. edodes 3721 growth. Moreover, in contrast with
other cultures, the MnP did not disappear during
the FB stage.
Finally, the data obtained indicate that the fruit
bodies yield depends on both the mushroom strain
and the growth substrate. Between two strains used
for tree leaf bioconversion, L. edodes 3715 gave
the lowest yield of mushroom during rst ush
with a BE of 74.8%, whereas the L. edodes 3721
BE achieved 83.4%. Data presented in Table 2
show that the L. edodes 3715 development distin-
guished from that of L. edodes 3721: the growth of
rst strain accompanied with an increase of medi-
um pH from 4.7 during the vegetative stage to 5.7–
5.8 in FB and PH stages, whereas the medium pH
ranged from 4.9 to 4.7 in cultivation of L. edodes
TABLE 2: Substrates pH and Reducing Sugars Content in Cultivation of L. edodes
Strains
Mushroom strain,
substrate/moistener
Medium pH Reducing sugars, mg/g
Stage of development
SC P FB PH SC P FB PH
L. edodes 3715, leaves/water 4.7 5.2 5.7 5.8 5.8 7.7 7.3 6.0
L. edodes 3721, leaves/water 4.9 4.5 4.7 4.6 10.1 10.5 10.3 13.0
L. edodes 3721, straw/water 4.9 4.5 4.5 4.6 15.4 13.5 16.1 14.0
L. edodes 3721, straw/medium 4.8 4.6 4.5 4.6 10.4 13.2 17.4 13.2
Volume 17, Number 1, 2015
Lentinus edodes Productivity and Lignocellulolytic Enzyme Proles during Wheat Straw and Tree Leaf Bioconversion 85
3721, which is optimal for catalytic activity of fun-
gal cellulase and xylanase. It can be speculated that
an elevated pH did not favor rapid hydrolysis of
tree leaf polysaccharides by L. edodes 3715. This
hypothesis is supported by the data on free sugars
content in growth substrate; namely, the reduc-
ing sugars content in this culture appeared to be
almost 2-fold lower compared with that in culti-
vation of L. edodes 3721. As mentioned above,
during mushroom cultivation on wheat straw (lig-
nied substrate with high content of crystalline
cellulose), higher levels of cellulase and xylanase
activities have been observed, especially the pres-
ence of additional nitrogen source. Owing to the
high hydrolase activity at favorable pH, the reduc-
ing sugars content during the FB stage reached
16–17 mg/g substrate (Table 2) and the mushroom
culture was steadily supplied with the carbon and
energy source to produce high yields of fruit bod-
ies with BE of 92%–95.3%. It is interesting that the
substrate formulations of sawdust, wheat bran, and
millet amended with 0.6%–1.2% sucrose, fructose,
or glucose resulted in a shiitake mushroom yield
increase by >11%.25
Thus, tree leaves and wheat straw are bene-
cial growth substrates for recycling into shiitake
fruit bodies by the commercial strains of L. edodes.
The data obtained clearly demonstrate physiologi-
cal and biochemical regularities taking place in
shiitake development on plant raw materials. The
correlation observed between mushroom growth
and enzyme production may be a good parameter
to estimate the period when the mushroom is ready
for fructication. However, further experiments in-
vestigating the impact of different substrates and
some nutrients on mushroom fruit bodies yield and
quality are needed.
ACKNOWLEDGMENTS
This work was supported by the Shota Rustaveli
National Science Foundation of Georgia (grant no.
10/05).
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