Suitability of Selected Supplemented Substrates for Cultivation of Kenyan Native Wood Ear Mushrooms (Auricularia auricula)
Different organic substrates namely maize cobs, wheat straw, grass straw and sugarcane bagasse supplemented with either wheat or rice bran were evaluated for production of two Kenyan native strains of wood ear mushroom [Auricularia auricula (L. ex Hook.) Underw.]. The objective was to evaluate the suitability of these substrates for cultivation of Kenyan native wood ear mushroom. Plastic bag technology was used with treatments arranged in a completely randomized design replicated three times. Samples of black and brown strains of the wood ear mushroom collected from woody stems of dead and dying trees within Kakamega forest were used in this study. Data was collected on days to pinning, fruit body quality, fruit body yields (number and fresh weight) and biological efficiency. The data collected was subjected to analysis of variance using SAS version 9.1. Mean separation was done using LSD and effects declared significant at 5% level. The two mushroom strains were not significantly (p>0.05) different in performance except for the number of fruit bodies where the black strain yielded significantly (p<0.05) higher than the brown one. The best performance was obtained from maize cobs and wheat straw substrates supplemented with wheat bran and these combinations were recommended to wood ear mushroom growers.
June 24, 2010; Accepted: August 18, 2010;
Published: September 28, 2010
Strong consumer demands and threats of depletion of mushrooms have stimulated
increased worldwide production in the past few decades (Chang
and Miles, 2004). The increased demand of mushrooms is due to their unique
culinary and medicinal properties (Yan et al., 2003).
However, Africa contributes a paltry 1% of the annual worldwide production of
mushrooms (Adejumo and Awosanya, 2005). In Kenya, commercial
mushroom production is limited to two exotic species namely; oyster and the
white button mushroom which are solely cultivated for the hotel industry (Gateri
et al., 2004). Indigenous mushrooms such as wood ear mushrooms [Auricularia
auricula (L. ex Hook.) Underw.] found in Kakamega forest in western Kenya
have not been studied to establish their cultivation potential.
The wood ears occur as saprophytes on stumps or at the bases of dead or dying
woody trees. The jelly-like fruit bodies of wood ears contain various bio-compounds
that have anti-tumor, antiviral, antibacterial and anti-parasitic effects making
it a choice food (Chang and Miles, 2004). Wood ear mushrooms
are a delicacy to communities residing around the Kakamega forest where they
are known as matere (Palapala et al., 2006).
The communities harvest the mushrooms throughout the year causing rapid diminishing
of the few remaining species (Palapala et al., 2006).
Further, the forest habitats are rapidly destroyed alongside the germplasm of
this fungus to create land for settlement and agriculture. These threats of
depletion necessitate development of cultivation techniques that can be easily
adopted by local farmers for conservation of this resource.
Extensive research has been carried out on the most efficient cultivation methods
for specialty mushrooms other than the wood ears (Royse
et al., 1990; Stamets, 2000). One of the greatest
challenges to mushroom cultivation is production of spawn used for bulk inoculation
of substrates (Oei, 2005). Another limiting factor towards
domestication of native mushrooms is identification of suitable lignocellulosic
substrates for cultivation. Palapala et al. (2006)
reported that Kenyan native wood ear mushrooms have the potential to be grown
on locally available substrates such as wheat straws, sugar bagasse, sawdust,
maize cobs and maize stalks. In order to achieve maximum yields, supplementation
of substrates with other nutrient bases such as soybean meal, rice and wheat
brans is necessary as they can reportedly increase mushroom yield two-fold (Royse
et al., 1991). Supplementation of substrates has therefore become
one of the major aspects of mushroom cultivation (Ayodele
and Akpaja, 2007).
This study utilized maize cobs, wheat straw, sugarcane bagasse and grass straw as the main ingredients to determine the best substrate for cultivation. Equal levels of rice and wheat brans were used as supplements to the substrates. The objective was to evaluate the suitability of these locally available organic substrates in production of Kenyan native wood ear mushroom. The study therefore outlines the cultivation protocols for native wood ears that can be adopted by rural farmers for nutritional and conservation purposes. Experiments for house management were designed and comparison of outputs done to recommend superior procedures for domestication.
MATERIALS AND METHODS
The study was conducted at Masinde Muliro University of Science and Technology
between September, 2007 and May, 2008. Four substrates namely grass straw, sugar
bagasse, wheat straw and maize cobs were tested in this experiment. To each
of the substrates, 20% of rice and wheat bran supplements were added. Plastic
bag technology was used with treatments arranged in a completely randomized
design replicated three times. Samples of black and brown strains (Fig.
1a,b) of wood ear mushrooms collected from woody stems
of dead and dying trees within Kakamega forest were used in this study.
|| (a) Brown and (b) black wood ears mushrooms from Kakamega
forest in western Kenya
|| Descriptors for fruit body quality
The substrates were cut into small pieces (<4 cm) using a sharp knife. They
were then submerged in water for 12 h to soften them. The substrates were separately
subjected to the short composting procedure using the methods of Sinden
and Hauser (1980). The substrates were divided into lots of 1 kg each and
packed into heat resistant polypropylene bags with a diameter of 12 cm and a
length of 20 cm. The ends of bags were tightly tied using sterile cotton strings
and autoclaved at 121°C for 1 h. The substrate bags were cooled to room
temperature for 30 min and inoculated using grain spawns obtained from the two
mushroom strains. The inoculated substrates were labeled and kept in total darkness
in enclosed cabinets for 14-25 days to allow complete colonization of the substrates.
Upon completion of spawn run, two holes 10 mm diameter were made on each bag.
After the substrate bags were fully colonized by mycelia, they were slit using a sharp razor at the sides while the tops were opened. Substrate temperatures were lowered to the fruiting range of 18-23°C by submerging the sealed substrates in cold-water refrigerator for 10 min. Air temperatures were lowered using two electric fans during the day. At night, the windows were left open to lower the room temperature. Humidity was maintained at between 90-95% through constant flooding of the floor with sterile water and spraying each bag of substrate with 1 liter of water twice a day. Fresh air was circulated using two electric fans. The room was lighted on a 12 h on/off cycle using two fluorescent bulbs of 100 watts. The duration taken by each bag to produce primordial was recorded and averaged for each replicate.
Three to four days after primordial formation, mature mushrooms were harvested. Data was recorded on quality, number and fresh weight of fully mature fruit bodies. Fruit body quality was evaluated on a scale of 1-4 using the descriptors in Table 1. The second flush grew more rapidly and was harvested in the same manner after 6-10 days. Used substrates from each bag were wrapped in aluminum foil and dried in an oven set at 80°C for 36 h. Percentage Biological Efficiency (BE) was calculated using the following formula:
The data collected was subjected to analysis of variance using SAS version 9.1. Mean separation was done using LSD and effects declared significant at 5% level.
Organic substrates and supplements tested were significantly different (p<0.05)
in suitability for wood ear mushroom cultivation. Generally, maizecob substrate
consistently gave the best results followed by wheat straw, sugar bagasse and
grass straw in that order. On the other hand, wheat bran supplement proved to
be better than rice bran (Table 2). Analysis of variance indicated
that the two mushroom strains were not significantly (p>0.05) different in
all the parameters that were measured except number of fruit bodies.
|| Effects of separate substrates and supplements on growth,
yield and quality
|| Effects of substrate supplementation on growth, yield and
|Means followed by the same letter along the same column are
not significantly different, GS: Grass straw, SB: Sugarcane bagasse, WS:
Wheat straw, MC: Maizecobs, RB: Rice bran, WB: Wheat bran
However, the black strain recorded numerically better results than the brown
one in all aspects. Strain by substrate interactions were highly significant
(p<0.0001) indicating that different mushroom strains responded differently
to different substrates.
Primordia formation was preceded by whitening of specific parts of the substrate surface and formation of sclerotia. Pinheads emerged as small rounded lumps that were grouped at particular parts of substrate surfaces. The substrates had variable effects on the duration to primordial formation ranging from 21 to 35 days for maize cobs and grass straw respectively. The supplements were also significantly variable with wheat bran taking a shorter time to pin averaging 26 days than rice bran which took an average of 29 days (Table 2). Consequently, the combination of maize cob and wheat bran resulted to the earliest primordial formation while grass straw and rice bran combination significantly delayed the pinning (Table 3). Analysis of variance indicated no significant (p>0.05) difference in primordia formation between the two mushroom strains.
The quality of fruit bodies evaluated on a scale of 1-4 varied significantly
(p = 0.05) among substrates and supplements tested. Maize cobs and wheat bran
combination produced large, erect and gelatinous fruit bodies that were auriform
in shape (Fig. 2) and were rated of the highest quality ranging
from a score of 2-4 (Table 3).
|| High quality wood ears fruiting on maizecobs supplemented
with wheat bran
The appearance of the mushrooms was excellent, with well-formed large caps
and conspicuous stems (Fig. 2). Grass straw gave the lowest
quality mushrooms followed by sugar baggase. Wheat straw and wheat bran combination
also gave good quality fruit bodies that ranged from 2-3 (Table
3). Supplemented wheat straw and sugarcane bagasse produced fruit bodies
of average quality since their characters were intermediary in terms of shape,
size and texture. The lowest quality fruit bodies were obtained from grass straw
especially when supplemented with rice bran (Table 3).
The number of marketable fruit bodies varied significantly (p<0.05) among substrates and supplements. Maizecobs and wheat bran combination produced the highest number of fruit bodies (17) followed by wheat straw and wheat bran combination (11). Grass straw produced the least number of fruit bodies ranging from 2-5 (Table 3). The fresh weight of fruit bodies also varied significantly (p<0.05) among the substrates with maize cob recording the highest fresh weight of 266.2 and 262.4 g of fruit bodies of brown and black strains respectively. Wheat straw produced 180 and 223.8 g of fruit bodies of brown and black strains respectively. Grass straw and sugar bagasse produced the least number of fruit bodies of the black (96) and brown (118) strains respectively (Table 2).
Biological Efficiency (BE) was calculated to determine how the mushrooms utilized nutrients present in the substrates efficiently. Average biological efficiency was significantly (p<0.05) different among different substrates and supplements tested. Maize cobs had the highest BE of 67% and 63.7% for the brown and black strains respectively. Wheat straw, sugar cane bagasse and grass straw had BE values of 40.8, 25.3 and 23.8%, respectively for brown strain and 55.2, 30.3 and 18.2%, respectively for black strain (Table 2). Rice bran was found to lower the BE of all substrates when used as a supplement unlike wheat bran which boosted the BE of all substrates (Table 3).
This study demonstrated that wheat straw and maize cobs are potentially suitable
for use in wood ear mushroom production. Wheat bran also proved to be a suitable
material for supplementing the two organic substrates. Ayodele
and Akpaja (2007) reported that supplementation of sawdust with 20% oil
palm fibers enhanced the mycelia growth and sporophore yield of Lentinus
squarosulus. Kimenju et al. (2009) also demonstrated
that mushrooms can be grown on several locally available organic substrates.
Nutritional composition of substrates is a crucial factor in determining how
mycelia growth and primordial initiation occurs (Royse,
1997; Stamets, 2005). Narain et
al. (2008) reported that mycelia growth and primordial development is
dependent on the lignocellulosic materials especially the carbon: nitrogen ratio.
Mushrooms are known to produce a wide range of hydrolytic and oxidative enzymes
that enable them to colonize, degrade and bio convert many lignocellulosic substrates
(Bano and Rajarathran, 1988).
Kimenju et al. (2009) indicated that the time
taken by the mycelia to start pinning after ramification depends on the substrates
used. Maize cobs and wheat straw took shorter time to primordial formation than
sugar bagasse while grass straw took the longest time. This concurred with the
findings of Kimenju et al. (2009) who obtained
the shortest time to pinning of Oyster mushroom (Pleurotus ostreatus)
on maize cobs. Ramzan (1982) obtained pin-heads of five
strains of P. ostreatus on wheat straw between 20-40 days. Supplementation
with wheat bran further shortened the time to pinning unlike in a previous study
where wheat bran reportedly caused contamination of the substrates (Nshemereirwe,
2004). These differences were attributed to nutritional variations among
the substrates. Materials with high quality lignin and cellulose contents reportedly
take longer time to start pinning compared to the substrates with low contents
of lignin and cellulose. This is because high nutrition materials make the mycelia
to remain vegetative for a longer period resulting in vigorous growth and late
pinning (Kimenju et al., 2009). It can therefore
be assumed that maizecobs and wheat straw had poor nutritional value compared
to grass straw. However, other factors such as high moisture content in a substrate
have been reported to cause delayed pinning (Kimenju et
The fruit body quality was significantly affected by the substrates and supplements.
Maize cobs and wheat straw produced high quality mushrooms especially when supplemented
with wheat bran. This contradicts with Shen (2001) who
obtained poor quality mushrooms at high levels of wheat bran but conforms to
Shen and Royse (2001) who reported that mushroom quality
might be improved by lowering the quantity of the wheat bran supplement in the
substrates. Shen (2001) also observed that increasing
wheat bran levels in sawdust substrates containing millet and rye or both improved
mushroom quality. Even though large sized fruit bodies were considered to be
of good quality and were rated highly, Shen and Royse (2001)
commented that this is an inferior quality since such fruit bodies tend to break
during packaging thereby reducing their quality.
Previous studies on wood ear cultivation suggest that the cellulose content
of the substrate and enzyme production of the mushrooms is important in determining
the yield of a mushroom crop. The variations observed in yield may be attributed
to the complexity of substrates in terms of their cellulose content resulting
in a difference in the rate of degradation by the mushroom enzymes. Maize cobs
and wheat bran combination produced the highest fruit body yield (number and
fresh weight) indicating that it was the most suitable for native wood ear mushroom
growth. Iqbal et al. (2005) realized the best
yield of P. ostreatus and Pleurotus sajarcaju from wheat straw.
Ayodele and Akhuoya (2007) obtained the highest yield
of Psathyrella atroumbonata on sawdust supplemented with wheat bran at
5%. Martinez-Carrera et al. (2002) reported that
the capacity of wood ear mushrooms to grow on agricultural wastes such as maize
cobs is due to their lignolytic enzymes that are necessary for degradation of
such substrates. Thomas et al. (1998) showed
that high lignocellulosic content of the substrate is important in fruit body
production. Zervakis et al. (2001) compared various
lignocellulosic contents of substrates such as wheat straw, sugar bagasse and
wood chips for various specialty mushrooms cultivation and concluded that varying
results could be obtained.
Very low fresh weights were recorded for fruit bodies collected from sugarcane
bagasse and grass straw. Schiler (1982) speculated that
the reduction in fresh weight of mushrooms might be associated with the absence
of certain specific nutrients especially the cellulose-based substrates. Thomas
et al. (1998) reported that the very complex nature of sugar bagasse
impedes its efficient conversion to fungal mycelium. In addition, its
possible that the mushroom received nutrition and energy from the abundant free
sugars that were present in the bagasse and therefore made limited use of the
cellulose fraction (Zervakis et al., 2001). The
grass straw used in this study had been stored for long accumulating phenolic
acid, which reduced its fruit body forming ability. A study done by Royse
(1996) showed that there is a significant relationship between phenolic
acid concentration in a given substrate and the enzymatic activity of developing
mushrooms that translates to the maximum size of the fruit bodies.
In this study, the average number of fruit bodies obtained in each bag was
quite low in comparison to previous work done on wood ear mushrooms (Wong
and Wells, 1987). This was attributed to accumulation of carbon dioxide
and temperature fluctuations in the cabinets during spawn running since environmental
conditions of the cabinets were not efficiently controlled. Shen
and Royse (2001) reported that accumulation of CO2 during spawn
running may cause decrease in initiation points thus reducing mushroom productivity.
Temperature fluctuations can also cause death of surface mycelia and sclerotia,
which may reduce the number of fruit bodies formed (Oei,
2005). Contamination of the substrates by green mould (Chaetomium olivacearum)
could also have contributed to low number of fruit bodies (Oei,
1996). The green mould competes with the mushroom for space, nutrients as
well as causing chemical alteration of the substrate, which hinders mushroom
development (Chang and Miles, 1989). The parts of the
substrate occupied by this fungus were unfavorable for mycelia growth and only
the parts devoid of infection were fully colonized and produced fruit bodies.
In addition, the infection led to falling off of several young fruit bodies
during watering due to their fragile nature. The contamination effect was greatest
in sugarcane bagasse and grass straw. The effect of wheat bran in reducing contamination
in sugar bagasse was significant.
The suitability of different substrates for mushroom cultivation was also confirmed
by the average biological efficiency which was variable among the substrates.
This concurred to the study done by Kimenju et al.
(2009). Being mainly jelly like in form, the wood ears require a medium
with a high proportion of lipids. According to Narain et
al. (2008) maizecobs have a considerably higher lipid component than
the rest of the substrates used in this study. Therefore, the lipids present
in the maize cobs must have been efficiently utilized by the wood ears resulting
in the high BE value. It was also observed that spawns of the black strains
were of superior quality and yielded more especially on wheat bran supplemented
substrates. The black strain also produced thick mycelia that were well condensed
in the grains thus recording higher BE values than the brown strain whose mycelia
were less vibrant. This confirms the previous reports that BE is highly affected
by the quality of the spawn the cultivated strain (Mandeel
et al., 2005; Bechara et al., 2005).
It is evident that many locally available organic substrates have high potential for utilization as substrates and/or supplements for mushroom production. In this study, maize cobs and wheat straw supplemented with wheat bran produced the best results and were recommended for wood ear mushroom production. Apparently, these locally available organic materials are rich in lignin and cellulose which are utilized by the mushroom mycelium as a source of nutrition.
This study was sponsored by the African Institute for Capacity Development (AICAD). Masinde Muliro University of Science and Technology is acknowledged for providing laboratory space, equipments and technical assistance. Thanks are due to Dr. George Odhiambo of Department of Botany and Horticulture, Maseno University, for his valuable assistance in data analysis. The authors are also greatly indebted to Mr. Wycliffe Masinde of Kakamega Environmental Education Program (KEEP) who provided guidance to the sites of germplasm collection.
Adejumo, T.O. and O.B. Awosanya, 2005. Proximate and mineral composition of four edible mushroom species from South Western Nigeria. Afr. J. Biotechnol., 4: 1084-1088.
Direct Link |
Ayodele, S.M. and E.O. Akpaja, 2007. Yield evaluation of Lentinus squarosulus (Mont) Sing. On selecte sawdust of economic tree species supplemented with 20% oil palm fruit fibers. Asian J. Plant Sci., 6: 1098-1102.
CrossRef | Direct Link |
Bano, Z. and S. Rajarathran, 1988. Pleurotus mushrooms Part II. Chemical composition, nutritional value, post harvest physiology, preservation and role as human food. Crit Rev. Food Sci. Nutr., 27: 87-158.
PubMed | Direct Link |
Bechara, M.A., P. Heinemann, P.N. Walker and C.P. Romane, 2005. Agaricus bisporus grain spawn substrate with S41 and S44 nutrient supplement. ASAE Paper No. 057008 St. Joseph Michigan. ASAE., http://asae.frymulti.com/abstract.asp?aid=19653&t=2.
Chang, S.T. and P.G. Miles, 1989. Edible Mushrooms and their Cultivation. 1st Edn., ERC Press, Bocaraton. pp: 345.
Chang, S.T. and P.G. Miles, 2004. Mushrooms: Cultivation, Nutritional Value, Medicinal Effect and Environment Impact. CRC Press, Boca Raton, pp: 415.
Gateri, M.W., A.W. Muriuki, M.W. Waiganjo and P. Ngeli, 2004. Cultivation and commercialization of edible mushrooms in Kenya: A review of prospects and challenges of smallholder production. Natl. Hort. Res. Center,
Iqbal, S.M., C.A. Rauf and M.I. Sheik, 2005. Yield performance of oyster mushroom on different substrates. Int. J. Agric. Biol., 7: 900-903.
Direct Link |
Kimenju, J.W., G.O.M. Odero, E.W. Mutitu, P.M. Wachira, R.D. Narla and W.M. Muiru, 2009. Suitability of locally available substrates for oyster mushroom (Pleurotus ostreatus) cultivation in Kenya. Asian J. Plant Sci., 8: 510-514.
CrossRef | Direct Link |
Mandeel, Q.A., A.A. Al-Laith and S.A. Mohamed, 2005. Cultivation of oyster mushrooms (Pleurotus sp.) on various lignocellulosic wastes. World J. Microbiol. Biotechnol., 21: 601-607.
Martinez-Carrera, D., M. Bonialla, W. Martinez, M. Sobal, A. Aguilar and P. Gonzalez, 2002. Characterization and cultivation of wild Agaricus species from Mexico. Micol. Applied Intern., 13: 9-24.
Narain, R., R.K. Sahu, S. Kumar, S.K. Garg, C.S. Singh and R.S. Kanaujia, 2008. Influence of different nitrogen rich supplements during cultivation of Pleurotus florida on maize cobs substrate. Environmentalist, 29: 1-7.
CrossRef | Direct Link |
Nshemereirwe, F., 2004. Mushroom cultivation in Uganda. Mushroom Growers Handbook 1, Oyster Mushroom Cultivation, Part III. Mushroom Worldwide. Regional Research, Chapter 10. pp: 220-223. http://www.fungifun.org/mushworld/Oyster-Mushroom-Cultivation/mushroom-growers-handbook-1-mushworld-com-chapter-10-3.pdf.
Oei, P., 1996. Mushroom Cultivation with Special Emphasis on Appropriate Techniques for Developing Countries. 2nd Edn., Backhuys, Amsterdam, The Netherlands, pp: 111-122.
Oei, P., 2005. Small scale mushroom cultivation. Agrodok, 40: 65-66.
Palapala, V.A., F.P. Miheso and O. Nandi, 2006. Cultivation potential of indigenous species of African wood ear mushrooms. Paper Presented at Masinde Muliro University, Kenya, pp: 1-21
Ramzan, M., 1982. Studies on the cultivation of oyster mushroom (Pleurotus spp.) in Faisalabad. M.Sc. Thesis, University of Agriculture, Faisalaba, Pakistan
Royse, D.J., 1996. Yield Stimulation of Shiitake by Millet Supplementation of Wood Chip Substrates. In: Mushroom Biology and Mushroom Products, Royse, D.J. (Ed.). State University Press, Philadelphia, pp: 283.
Royse, D.J., 1997. Specialty mushrooms and their cultivation. Hortic. Rev., 19: 59-97.
Royse, D.J., B.D. Bahler and C.C. Bahler, 1990. Enhanced yield of Shiitake by saccharide amendment of the synthetic substrate. Applied Environ. Microbiol., 56: 479-482.
Royse, D.J., S.L. Fales and K. Karunananda, 1991. Influence of formal-dehyde-treated soyabean and commercial nutrient supplementation on mushroom (Pleurotus sajor-caju) yield and in vitro dry matter digestibility of spent substrate. Applied Microbiol. Biotechnol., 36: 425-429.
Schiler, L.C., 1982. New Innovations for Efficient Mushroom Growing. In: Pennyslavania State Handbook for Commercial Mushroom Growers, Weust, P.J. and G.D. Bengstone (Eds.). 2nd Edtn., The Pennyslavania State University, UK., pp: 117-118.
Shen, Q. and D. Royse, 2001. Effect of nutrient supplement on biological efficiency, quality and crop cycle time on maittake (Griofola frondosa). Applied Microbiol. Biotechnol., 57: 74-78.
CrossRef | Direct Link |
Shen, Q., 2001. Molecular Phylogenetic Analysis of Grifola Frondosa (Maitake) and Related Species and the Influence of Selected Nutrient Supplements on Mushroom Yield. The Pennsylvania State University, Pennsylvania, pp: 144.
Sinden, J.W. and E. Hauser, 1980. The nature of the short composting process and its relation to short composting. Mushroom Sci., 2: 123-131.
Stamets, P., 2000. Growing of Gourmet and Medicinal Mushrooms. 3rd Edn., Ten Speed Press, Berkeley, pp: 574.
Stamets, P., 2005. Mycelium Running: How Mushrooms Can Help Save the World. Ten Speed Press, Berkeley, CA.
Thomas, G.V., S. Prabhu, R. Reen and B. Bopaiah, 1998. Evaluation of lignocellulosic biomass from coconut palm substrate for cultivation of Pleurotus sajor caju. World J. Microbial. Biotechnol., 14: 879-882.
Wong, G. and K. Wells, 1987. Comparative morphology, compatibility and infertility of Auricularia maizeea, A. Polytricha and A. Tenuis. Mycol. Mycol. Soc. Am., 79: 847-856.
Yan, P., X. Luo and Q. Zhou, 2003. RAPD molecular differentiation of the cultivated strains of the jelly mushrooms Auricularia auricula and A. Polytricha. World J. Microbiol. Biotechnol., 17: 795-799.
Zervakis, G.A., S. Philippoussis, S. Ioannidas and T. Diamantoupolous, 2001. Mycelium growth kinetics and optimum temperature conditions for cultivation of edible mushroom species on lignocellulosic substrates. Fol. Micro., 46: 231-234.