Selection of a highly productive strain of Pholiota adiposa

Abstract

Comparative studies on mushroom strains from various localities are one of the best ways to screen for strains with improved yield and quality. The current study was conducted to evaluate the mycelial growth rate, primordial initiation time, biological efficiency, and nutritional components of four domesticated and one cultivar (Control) strain of Pholiota adiposa. Strain JZB2116005 exhibited the highest mycelial growth rate (2.56 ± 0.03 mm/d), whereas the control strain JZB2116001 was lowest (2.34 ± 0.01 mm/d). The mycelial colonization time and primordial initiation time of different strains were not consistent with the mycelial growth rates. It took approximately 8-9 days and 11-12 days longer for control strain JZB2116001 to colonize the whole bags and to form primordial, than strain JZB2116005. The highest biological efficiency (67.88 ± 1.33%) was observed in strain JZB2116005 while the control strain JZB2116001 was worst (41.35 ± 1.72%). Fruiting bodies of strain JZB2116005 showed better morphological traits and higher chemical contents as compared with the control strain JZB2116001. Therefore, from a commercial point of view, it was necessary to replace strain JZB2116001 with strain JZB2116005 in production.

Full text

Submitted 14 March 2016, Accepted 25 April 2016, Published online 30 April 2016
Corresponding Author: Shou X. Wang – e-mail – wangshouxian@baafs.net.cn 226
Selection of a highly productive strain of Pholiota adiposa
Rong CB1, Song S1, Niu YR1, Xu F1, Liu Y1, 2, Zhao S1, Wang SX1, 2
1 Institute of Plant and Environment Protection, Beijing Academy of Agriculture and Forestry Sciences, Beijing
Engineering Research Center for Edible Mushroom, Beijing 100097, China;
2 Key Laboratory of Urban Agriculture (North), Ministry of Agriculture, Beijing 100097, China.
Rong CB, Song S, Niu YR, Xu F, Liu Y, Zhao S, Wang SX 2016 – Selection of a highly productive
strain of Pholiota adiposa. Mycosphere 7(2), 226–235, Doi 10.5943/mycosphere/7/2/11
Abstract Comparative studies on mushroom strains from various localities are one of the best ways
to screen for strains with improved yield and quality. The current study was conducted to evaluate
the mycelial growth rate, primordial initiation time, biological efficiency, and nutritional
components of four domesticated and one cultivar (Control) strain of Pholiota adiposa. Strain
JZB2116005 exhibited the highest mycelial growth rate (2.56 ± 0.03 mm/d), whereas the control
strain JZB2116001 was lowest (2.34 ± 0.01 mm/d). The mycelial colonization time and primordial
initiation time of different strains were not consistent with the mycelial growth rates. It took
approximately 8–9 days and 11–12 days longer for control strain JZB2116001 to colonize the
whole bags and to form primordial, than strain JZB2116005. The highest biological efficiency
(67.88 ± 1.33%) was observed in strain JZB2116005 while the control strain JZB2116001 was
worst (41.35 ± 1.72%). Fruiting bodies of strain JZB2116005 showed better morphological traits
and higher chemical contents as compared with the control strain JZB2116001. Therefore, from a
commercial point of view, it was necessary to replace strain JZB2116001 with strain JZB2116005
in production.
Key words – biological efficiency – cultivation – nutritional components – yield
Introduction
Pholiota adiposa (Fr.) Quel., an edible and medicinal mushroom, is widely distributed on
the dead timber piles of poplars, willows, or birches in forest areas in China (Hu et al. 2012). The
fruiting body of this mushroom is rich in proteins, essential amino acids, dietary fiber, trace
elements, vitamins, and carbohydrates (Hui et al. 2003). Compounds extracted from the fruiting
bodies of P. adiposa display a variety of important biological activities, such as antitumor (Jiang et
al. 2007, Zhang et al. 2009, Hu et al. 2012), antimicrobial (Dulger 2004), anti-HIV-1 (Zhang et al.
2009, Wang et al. 2014a) and antioxidative activities (Ji et al. 2007, Deng et al. 2011, Wang et al.
2014a). Owing to the important nutritional and medicinal properties, cultivation of P. adiposa is
prevalent worldwide, not only in China but also in several regions of Asia, Europe, and North
America (Shimizu et al. 2003).
Recently, numerous reports regarding the comparative cultivation studies of Hericium
species (Ko et al. 2005), Flammulina velutipes (Wang & Wen 2014, Zhang et al. 2015), Pleurotus
spp. (Zhang et al. 2012, Wang et al. 2014b), Pleurotus eryngii (Wu et al. 2011), Pleurotus ostreatus
(Salmones et al. 2005), and Tremella fuciformis (Deng et al. 2014) have been published. However,
Mycosphere 7 (2): 226–235(2016) www.mycosphere.org ISSN 2077 7019
Article
Doi 10.5943/mycosphere/7/2/11
Copyright © Guizhou Academy of Agricultural Sciences

227
the cultivation history of P. adiposa is poorly studied, hence, only a few papers are available on the
cultural characteristics of P. adiposa (Morimoto et al. 1979, Meng et al. 2006, Shen et al. 2009, Li
& Qi 2010, Li et al. 2015). There are no comparative studies of different P. adiposa strains.
Therefore, the present study was initiated to compare the P. adiposa industrial cultivar with
4 new domesticated strains. These strains were evaluated in our preliminary estimation from 12
wild P. adiposa strains. Mycelial growth rate (MGR), primordial initiation time (PIT), biological
efficiency (BE), and nutritional value of the fruiting bodies were tested to screen an efficient strain
with good cultivation traits and nutritional components.
Materials & Methods
Microorganism and spawn preparation
Twelve P. adiposa fruiting bodies collected from different places in Beijing, China, were
isolated by tissue culture. The MGR, PIT, and BE were screened in our preliminary estimation.
Eight strains were discarded for easily being contaminated by mold or unformed fruiting bodies in
cultivation and four strains with relatively good cultivation traits were selected for further study
(unpublished data). One cultivar (JZB2116001) with poorly cultivation traits was used as control in
this study (Table 1). All the tested strains were deposited in the Beijing Engineering Research
Center for Edible Mushroom, Beijing Academy of Agriculture and Forestry Sciences (BAAFS),
Beijing, China.
Cultures were maintained on a potato dextrose agar (PDA, 200 g/l of diced potatoes; 20 g/l of
glucose; 15 g/l of agar) medium at 25 °C. The spawn preparation was conducted according to the
method described by Pant et al. (2006).
Substrate preparation, inoculation, and incubation
The cottonseed hulls, sawdust (Malus sylvestris), and wheat bran used in this study for
cultivation of P. adiposa, were obtained from Beijing Yingliang Agricultural Development Co., Ltd
(Beijing, China) and sun-dried. Substrates were prepared with 65% (w/w) water content containing
60% cottonseed hull, 18% sawdust, 15% wheat bran, 5% corn flour, 1% gypsum, and 1% lime and
placed in polypropylene bags (17 cm × 33 cm × 0.04 cm) at a packing density of 1,000 g of
substrate per bag. A specially designed plastic ring was wrapped at the top end of the bag to form
an opening, and an oblong conical plastic rod with a short rope was used to fill the bag from the
opening. Then the top plastic ring was covered with a vent cap with microbiological filters. The
bags were autoclaved at 121 °C for 120 min. After sterilization, the plastic ring was open carefully
and the oblong conical plastic rod was pulled out, a hole was left in the bag, and the spawns were
inoculated into the hole at an amount of 2% (w/w) of substrate fresh weight. Two-hundred-fifty
replicated polypropylene bags were used and were divided into five replicates for each treatment.
Same substrates were placed in racing tubes for MGR measurements following the
method described by Gregori et al. (2008), with a modification of the tube size (30-mm diameter,
260 mm length). Eighty grams of substrate per racing tube were used and sealed with cotton plugs
on both sides of the tube. Racing tubes were autoclaved at 121 °C for 120 min. Sterilized tubes
were inoculated on one side by spreading the spawn on the substrates at an amount of 2% (w/w) of
substrate fresh weight. Five replicates were prepared for each strain.
The inoculated bags and tubes were kept in the spawn running room at 23–25 °C and 50–
60% relative humidity (RH) under dark conditions. MGR on substrates filled in racing tubes was
measured by the height (mm) of the mycelia in the colonized substrates divided by the incubation
time (days). Mycelial colonization time (MCT) (number of days from inoculation to complete
colonization of the substrate by the mycelium in the culture bag) and PIT (number of days from
inoculation to pinhead fruiting bodies) were recorded.

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Table 1 Sample data of the tested Pholiota adiposa strains.
Strain No.
Origin
Host
Acquisition
time
JZB2116001
Beijing Academy of Agriculture and Forestry Sciences
(BAAFS), Beijing, China
––
––
JZB2116003
Lingshan, Mentougou district, Beijing, China
Willow
2009.07.20
JZB2116004
Lingshan, Mentougou district, Beijing, China
Willow
2009.07.15
JZB2116005
Zizhuyuan park, Haidian district, Beijing, China
Willow
2009.09.12
JZB2116007
Beijing Vegetable Research Center, BAAFS, Beijing, China
Willow
2010.10.09
Cropping, harvest, and determination of BE
After a complete spawn run, the bags were transferred to a refrigerated house to induce
an occurrence of primordia and were cultured for 3–5 d at 0–5 °C. Then, the bags were moved to a
fruiting chamber that was maintained at 18 ± 2 °C and 80–90% RH with 12 h of illumination (300–
600 Lux). Bags were unfolded at the upper parts for cropping. To maintain the desired humidity,
the chamber was sprayed intermittently during the growing time.
Fruiting bodies in two flushes were harvested before the caps started to open. The
morphological traits of the fruiting bodies, including the pileus diameter and thickness, stipe length
and diameter, were measured by digital calipers (Mitutoyo, Japan). The harvested fruiting bodies in
each bag were weighed. At the end of the harvesting period, the accumulated data were used to
calculate the BE (Yang et al. 2013).
BE (%) = Weight of fresh mushrooms harvested per bag/weight of dry weight per bag × 100
Chemical analysis and statistical analysis
Fruiting bodies of P. adiposa were collected randomly from the five tested strains in
equal proportions after the first flush. Then they were dried in an oven at 60 °C to a constant weight
and kept at 4 °C. The chemical compositions, including moisture, dietary fiber, protein, energy, fat,
ash, carbohydrate, and amino acids, of the samples were analyzed following the methods of Wang
et al. (2015). All of the above analyses were performed by the PONY Testing International Group
(Beijing, China).
Statistical analyses were conducted using the evaluation version of SPSS 20.0 for
Windows. Data were obtained from two consecutive harvests, and chemical analyses were
subjected to one-way analysis of variance. Differences among the means of eight treatments were
assessed using Duncan’s multiple range tests at the 95% confidence level.
Results
Mycelial growth and primordial initiation of different strains
All the tested strains colonized on the substrates containing 60% cottonseed hull, 18%
sawdust, 15% wheat bran, 5% corn flour, 1% gypsum, and 1% lime. Out of the tested strains, the
highest MGR was observed for strain JZB2116005, followed by strain JZB216004; the control
strain JZB2116001 showed the lowest MGR. The values of the MGR of the above three strains
were 2.56 ± 0.03 mm/d, 2.45 ± 0.03 mm/d, and 2.34 ± 0.01 mm/d, respectively. There was a
significant difference between strain JZB2116005 and the others with regard to the MGR; no
difference was observed among strains JZB2116001, JZB2116003, and JZB2116007 (Figure 1 A).
Correspondingly, the MCT and PIT of different strains were inconsistent with the MGR. It took
approximately 8–9 d and 11–12 d longer for the control strain JZB2116001 to colonize whole bags
and form primordia than strain JZB2116005, respectively (Figure 1 B, C).

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Fig. 1 – Comparison of the mycelial growth rate (MGR) (A), mycelial colonization time (MCT)
(B), primordial initiation time (PIT) (C), and biological efficiency (BE) (D) of the tested Pholiota
adiposa strains.
A, MGR was measured by the height (mm) of the mycelia in the colonized substrates in racing
tubes divided by the incubation time (days). B, MCT was measured by number of days from
inoculation to complete colonization of the substrate by the mycelium in the culture bag. C, PIT
was measured by number of days from inoculation to pinhead fruiting bodies. D, BE (%) = Weight
of fresh mushrooms harvested per bag/weight of dry weight per bag × 100.
Table 2 Comparison of the morphological traits of the tested Pholiota adiposa fruiting bodies a
(mm) (mean ± SD, n= 20).
Strain No.
Stipe length
Stipe Diameter
Pileus thickness
Pileus diameter
JZB2116001
94.83 ± 4.83a
9.67 ± 1.03b
9.17 ± 0.41a
45.67 ± 3.61a
JZB2116003
90.00 ± 6.28a
9.60 ± 0.55b
7.40 ± 1.34b
23.60 ± 5.18bc
JZB2116004
72.40 ± 7.13b
11.40 ± 2.79b
6.00 ± 0.71c
18.40 ± 2.07c
JZB2116005
95.80 ± 8.67a
11.00 ± 1.58b
7.80 ± 0.84b
25.40 ± 5.41b
JZB2116007
65.20 ± 5.54b
16.00 ± 1.87a
8.20 ± 2.05ab
28.60 ± 4.34b
aMeans in each column followed by the same superscripts are not significantly different at P<0.05
according to Duncan’s multiple range tests.

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Table 3 Comparison of the chemical compositions of the tested Pholiota adiposa fruiting bodiesa
(g in 100 g of dry matter, mean ± SD, n= 3).
Parameter
JZB2116001
JZB2116003
JZB2116004
JZB2116005
JZB2116007
Moisture (g)
6.82 ± 0.05a
6.82 ± 0.04a
6.78 ± 0.03a
6.80 ± 0.06a
6.78 ± 0.09a
Ash (g)
6.12 ± 0.03c
6.20 ± 0.12c
7.44 ± 0.19a
7.36 ± 0.15a
6.60 ± 0.12b
Protein (g)
21.90 ± 0.14c
23.20 ± 0.30b
27.20 ± 0.11a
26.60 ± 0.80a
23.20 ± 0.42b
Fat (g)
2.10 ± 0.01b
1.70 ± 0.05d
2.30 ± 0.01a
1.90 ± 0.03c
2.40 ± 0.13a
Dietary fiber (g)
30.50 ± 0.23a
31.10 ± 0.58a
30.50 ± 0.81a
27.40 ± 0.82b
27.70 ± 0.78b
Carbohydrate (g)
32.56 ± 0.25a
30.98 ± 1.01ab
25.78 ± 1.13c
29.94 ± 1.84b
33.32 ± 1.28a
Energy (kcal)
298.16 ± 1.53b
294.64 ± 1.92c
293.92 ± 2.02c
298.92 ± 5.05b
303.83 ± 2.01a
a Means in each column followed by the same superscripts are not significantly different at P<0.05
according to Duncan’s multiple range tests.
Table 4 Comparison of the amino acid concentration and composition of tested Pholiota adiposa
fruiting bodiesa (g in 100 g of dry matter, mean ± SD, n= 3).
Amino acids
JZB2116001
JZB2116003
JZB2116004
JZB2116005
JZB2116007
Asparagine
1.46 ± 0.01c
1.57 ± 0.02b
1.87 ± 0.02a
1.24 ± 0.05d
1.09 ± 0.03e
Threonineb
0.75 ± 0.01c
0.79 ± 0.03b
0.98 ± 0.01a
0.68 ± 0.03d
0.59 ± 0.02e
Serine
0.78 ± 0.01c
0.87 ± 0.04b
1.01 ± 0.04a
0.66 ± 0.03d
0.58 ± 0.01e
Glutamic acid
3.21 ± 0.05b
3.00 ± 0.12c
4.17 ± 0.14a
2.30 ± 0.09d
2.31 ± 0.01d
Proline
0.70 ± 0.03b
0.72 ± 0.01b
0.86 ± 0.01a
0.56 ± 0.05c
0.56 ± 0.01c
Glycine
0.66 ± 0.01c
0.72 ± 0.01b
0.86 ± 0.01a
0.57 ± 0.02d
0.51 ± 0.02e
Alanine
0.88 ± 0.01c
0.95 ± 0.01b
1.13 ± 0.01a
0.78 ± 0.03d
0.68 ± 0.02e
Cystine
0.13 ± 0.01c
0.18 ± 0.00b
0.20 ± 0.00a
0.13 ± 0.01c
0.13 ± 0.01d
Valineb
0.71 ± 0.00c
0.77 ± 0.01b
0.94 ± 0.01a
0.64 ± 0.03d
0.56 ± 0.02e
Methionineb
1.03 ± 0.02cd
1.25 ± 0.08b
2.60 ± 0.16a
1.04 ± 0.05cd
1.16 ± 0.04bc
Isoleucineb
0.73 ± 0.01c
0.83 ± 0.01b
0.98 ± 0.01a
0.71 ± 0.04cd
0.67 ± 0.05d
Leucineb
1.19 ± 0.01cd
1.33 ± 0.05b
1.55 ± 0.02a
1.12 ± 0.06d
1.00 ± 0.09e
Tyrosine
0.40 ± 0.00c
0.47 ± 0.01b
0.53 ± 0.00a
0.37 ± 0.02d
0.33 ± 0.02e
Phenylalanineb
0.80 ± 0.01c
0.90 ± 0.03b
1.03 ± 0.03a
0.69 ± 0.03d
0.62 ± 0.03e
Lysineb
0.82 ± 0.01d
0.97 ± 0.01b
1.11 ± 0.01a
0.88 ± 0.04c
0.80 ± 0.03d
Histidine
0.33 ± 0.00c
0.38 ± 0.01b
0.43 ± 0.01a
0.33 ± 0.02c
0.31 ± 0.01d
Tryptophanb
0.20 ± 0.00e
0.28 ± 0.00b
0.33 ± 0.01a
0.24 ± 0.00cd
0.25 ± 0.01c
Arginine
1.10 ± 0.02c
1.19 ± 0.02b
1.53 ± 0.02a
0.84 ± 0.04d
0.81 ± 0.04d
EAAc
6.23 ± 0.04c
7.11 ± 0.21b
9.52 ± 0.26a
5.99 ± 0.28cd
5.62 ± 0.27d
NEAAd
9.65 ± 0.12b
10.03 ± 0.24b
12.59 ± 0.26a
7.79 ± 0.35c
7.30 ± 0.17d
TAAe
15.88 ± 0.17c
17.14 ± 0.45b
22.11 ± 0.51a
13.78 ± 0.62d
12.92 ± 0.44e
EAA/NEAAf (%)
64.56 ± 0.37c
70.88 ± 0.40b
75.64 ± 0.49a
76.86 ± 0.13a
77.01 ± 1.96a
EAA/TAAg (%)
39.23 ± 0.14c
41.48 ± 0.14b
43.06 ± 0.16a
43.46 ± 0.04a
43.50 ± 0.63a
a Means in each column followed by the same superscripts are not significantly different at P<0.05
according to Duncan’s multiple range tests.
b Essential amino acids.
c EAA, total concentration of essential amino acids.
d NEAA, total concentration of non-essential amino acids.
e TAA, total concentration of amino acids.
f EAA/NEAA, total concentration of essential amino acids/total concentration of non-essential
amino acids.
g EAA/TAA, total concentration of essential amino acids/total concentration of amino acids.

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Table 5 Comparison of the chemical composition of different origins of the Pholiota spp. strains (g
in 100 g of dry matter).
Substrates
Protein
Fat
Ash
Dietary
fiber
Carbohydrate
Essential
amino
acids/Total
amino acids
(%)
Essential amino
acids/ non-
Essential amino
acids (%)
Current study
21.90–
27.20
1.70–
2.40
6.12–
7.44
27.40–
31.10
25.78–33.32
39.23–43.60
64.56–77.29
P. squarrosoides
(Wang et al.
2014c)
11.80
1.50
5.50
32.90
41.68
46.00
85.19
P. adiposa (Hui et
al. 2003)
21.64
1.22
5.88
––
––
37.87
60.95
P. nameko (Xiang
et al. 2013)
24.98
3.21
6.38
––
––
28.10*
39.08*
* Tryptophan, one of the essential amino acids, was undetected.
Production of P. adiposa
BE and morphological traits of the tested P. adiposa fruiting bodies were presented in
Figure 1 D and Table 2, respectively. The highest BE of fruiting bodies (67.88 ± 1.33%) was for
strain JZB2116005, followed by strain JZB216007, with a BE of 55.91 ± 1.65%; the control strain
JZB2116001 showed the lowest BE of fruiting bodies (41.35 ± 1.72%). There was a significant
difference between strain JZB2116005 and the others, and no difference was observed among
strains JZB2116001, JZB2116003, and JZB2116004. Strain JZB2116005 displayed the longest
stipe length (95.80 ± 8.67 mm), but no significant difference was observed with strains
JZB2116001 and JZB2116003; the values were 94.83 ± 4.83 mm and 90.00 ± 6.28 mm,
respectively. Strain JZB2116007 had the shortest stipe length (65.20 ± 5.54 mm) and the largest
stipe diameter (16.00 ± 1.87 mm). The control strain JZB2116001 showed the largest value in the
thickness and diameter of the pileus, with measurements of 9.17 ± 0.41 mm and 45.67 ± 3.61 mm,
respectively.
Chemical contents of P. adiposa
Table 3 indicates the chemical compositions of the P. adiposa fruiting bodies from
different tested strains. Moisture contents of the P. adiposa samples were not significantly different
among the tested strains. Ash content of the P. adiposa samples varied from 6.12 to 7.44 g. The
highest protein content was found in strain JZB2116004 (27.20 ± 0.11 g), followed by strain
JZB2116005 (26.60 ± 0.80 g); the control strain JZB2116001 displayed the lowest protein content
(21.90 ± 0.14 g). Strains JZB2116004 and JZB2116005 showed no significant difference in protein
content, but had a significant difference compared with the others. The fat content in strain
JZB2116005 was 1.90 ± 0.03 g, which was higher than that of strain ZJB2116003 and lower than
the other three tested strains. The highest amount of dietary fiber was found in strain JZB2116003
(31.10 ± 0.58 g), followed by strains JZB2116001 and JZB2116004, which had an similar dietary
fiber amount (30.50 ± 0.23 g, 30.50± 0.81 g ); the lowest was in strain JZB2116005, with a dietary
fiber amount of 27.40 ± 0.82 g. The carbohydrate content in strain JZB2116005 was 29.94 ± 1.84 g,
which was higher than that of strain JZB2116004 (25.78 ± 1.13 g) and lower than the others. The
highest energy was recorded in strain JZB2116007 with 303.83 ± 2.10 kcal, followed by strains
JZB2116005 and JZB2116001, with energy values of 298.92 ± 5.05 and 298.16 ± 1.53 kcal,
respectively. Strain JZB2116004 demonstrated the lowest energy value (293.92 ± 2.02 kcal).
Table 4 shows the concentrations of amino acids in different P. adiposa fruiting bodies.
Interestingly, there was some regularity in the concentrations of the 18 amino acids in tested
strains. The highest concentration of the 18 amino acids was in strain JZB2216004, followed by

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strain JZB2116003, except for glutamic acid, which showed a lower concentration (3.00 ± 0.12 g)
than that in control strain JZB2116001 (3.21 ± 0.05 g). Total concentration of amino acids (TAA)
in strain JZB2116005 was 13.78 ± 0.62 g, which was higher than that in strain JZB2116007 (12.92
± 0.44 g) and lower than the other three strains. Ratios of total concentration of essential amino
acids (EAA)/total concentration of non-essential amino acids (NEAA) and EAA/TAA of the five
tested strains were demonstrated in Table 4, the highest values were in strain JZB2116007 (77.01 ±
1.96% and 43.50 ± 0.63%, respectively), followed by strain JZB2116005 (76.86 ± 0.13% and 43.46
± 0.04%, respectively) and JZB2116004 (75.64 ± 0.49% and 43.06 ± 0.16%, respectively). There
were no significant differences among these three strains, and the lowest values were in control
strain JZB2116001 (64.56 ± 0.37% and 39.23 ± 0.14%, respectively).
Discussion
In mushroom cultivation, the MGRs, PIT, yield, and BE are easily affected by the
genotypes of the strains, the origins of the substrates, and the atmospheric conditions, which are
typically different. In this study, the fruiting bodies of all the tested P. adiposa strains were
successfully obtained on the substrates containing 60% cottonseed hull, 18% sawdust, 15% wheat
bran, 5% corn flour, 1% gypsum, and 1% lime. Strain JZB2116005 displayed the best characters
compared with the others, especially with the control strain JZB2116001. The MGRs of the tested
strains were correspond with the BE, but inconsistent with the MCT and PIT (Figure 1). The result
of the present study was in agreement with that of Philippoussis (2001) and Baysal (2003) for the
cultivation of P. ostreatus and Naraian (2009) for the cultivation of P. florida. Both of them
reported rapid MGR, earlier PIT, and higher yield. However, in our previous comparision studies of
tested strains with P. squarrosoide strain, P. squarrosoide demonstrated the significant difference
in MGR, which was approximately 6 d earlier for colonizing the bags than P. adiposa JZB2116005,
but it needed further 20–22 d for the after-ripening of the mycelia and the BE was 51.29% (Wang
et al. 2014c), which was lower than that of P. adiposa strains JZB2116005 (67.88 ± 1.33%) and
JZB2116007 (55.91 ± 1.65%) (Figure 1 D) and displayed significant differences among each other
(Data not shown). Therefore, strains with the highest MGR should represent a better physiological
index that can colonize the whole substrates in a short time and avoid contamination, but the MGR
should not be the only index to evaluate the quality of the strains in production. The BE of five
tested P. adiposa strains was between 41.35 and 67.88% (Figure 1 D); strain JZB2116005 was
1.64–fold higher than the control strain JZB2116001, with a BE of 67.88 ± 1.33% and 41.35 ±
1.72%, respectively. In addition, among the morphological traits of tested P. adiposa fruiting
bodies, strain JZB2116005 demonstrated better morphological traits, with the longest stipe length
and medium stipe diameter, pileus thickness, and pileus diameter, which were preferred by
consumers, in comparison with the other tested strains.
Recently, many mushroom chemical analyses have been reported (Lee et al. 2011,
Kulshreshtha et al. 2013, Wang et al. 2014c, Fernandes et al. 2015, Wang et al. 2015, Xu et al.
2015). However, the chemical composition is also easily affected by the strain genotype, substrate
origin, and atmospheric conditions, which are usually different. In the present study, the chemical
compositions and amino acids of the five tested P. adiposa strains were determined (Tables 3, 4),
and comparisons of chemical their composition, EAA/TAA ratios and EAA/NEAA ratios of the
five tested P. adiposa strains with the closely related species in literature are shown in Table 5. The
protein contents varied from 21.90 g to 27.20 g and were higher than those of P. squarrosoide
(11.80 g) (Wang et al. 2014c) and P. adiposa (21.64 g) (Hui et al. 2003). Of the five tested strains,
the protein contents of strains JZB2116004 and JZB2116005 were 27.20 ± 0.11 g and 26.60 ± 0.80
g, respectively, which were higher than that of P. nameko (24.98 g) (Xiang & Chen 2013). The fat
contents (1.70–2.40 g) were higher than those of P. squarrosoide (1.50 g) (Wang et al. 2014c) and
P. adiposa (1.22 g) (Hui et al. 2003) and lower than that of P. nameko (3.21 g) (Xiang & Chen
2013). The ash contents varied from 6.12 g to 7.44 g and were higher than those of P. squarrosoide
(5.50 g) (Wang et al. 2014c) and P. adiposa (5.88 g) (Hui et al. 2003). Of the five tested strains, the
ash content of strains JZB2116004, JZB2116005, and JZB2116007 were 7.44 ± 0.19 g, 7.36 ± 0.15

233
g, and 6.60 ± 0.12 g, respectively, which were higher than that of P. nameko (6.38 g) (Xiang &
Chen 2013). The dietary fiber and carbohydrate contents of tested strains were 27.40–31.10 g and
25.78–33.32 g, respectively, which were all lower than those of P. squarrosoide with values 32.90
g and 41.68 g, respectively (Wang et al. 2014c). The values of EAA/TAA and EAA/NEAA were
39.23–43.60% and 64.56–77.29%, respectively, which were all lower than those of P. squarrosoide
(46.00% and 85.19%, respectively) (Wang et al. 2014c), whereas they were higher than those of P.
adiposa (37.87% and 60.95%, respectively) (Hui et al. 2003) and P. nameko (28.10% and 39.08%,
respectively) (Xiang & Chen 2013). In addition, these values of the five tested strains were well
above 40% EAA/TAA, and 60% EAA/NEAA is considered to be adequate for an ideal protein food
(FAO/WHO, 1973), except for the control strain JZB2116001, with 39.23% EAA/TAA. Therefore,
from chemical analyses, it could be concluded that fruiting bodies of strain JZB2116005
demonstrated better nutritional properties compared with the others. And it was necessary to
optimize the cultivation formula or environmental factors of strain JZB2116005 for improving its
chemical contents in the further research.
In conclusion, this is the first report of a comparative study on P. adiposa strains with
different origins. From a commercial point of view, strain JZB2116005 has a clear advantage over
the control strain JZB2116001 in terms of MGR, MCT, yield, BE, chemical compositions, and
amino acid contents, and it is necessary to substitute strain JZB2116001 in production. Our findings
will provide the foundation required for upgrading strains of other mushroom species in cultivation.
Acknowledgements
This work was financially supported by the Beijing Agriculture Innovation Consortium
(BAIC05-2016), the Special Science and Technology Innovation Project of BAAFS
(KJCX20151408) and the Major Program of Beijing Municipal Science & Technology
Commission (D151100004315003). We would like to thank to Prof. Xiaolan Mao (Institute of
Microbiology, Chinese Academy of Sciences), for identification of the wild Pholiota strains and Dr.
Jiye Yan (Institute of Plant and Environment Protection, Beijing Academy of Agriculture and
Forestry Sciences), for providing valuable suggestions on the manuscript.
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