Spent substrate, the residual material of mushroom cultivation, causes disposal problems for
cultivators. Currently the spent substrate of different mushrooms is used mainly for composting. Edible
mushrooms of Pleurotus sp. can grow on a wide range of lignocellulosic substrates. In the present study,
Pleurotus eous was grown on paddy straw and the spent substrate was used for the production of ethanol.
Lignocellulosic biomass cannot be saccharified by enzymes to high yield of ethanol without pretreatment. The
root cause for the recalcitrance of lignocellulosic biomass such as paddy straw is the presence of lignin and
hemicelluloses on the surface of cellulose. They form a barrier and prevent cellulase from accessing the
cellulose in the substrate. In the untreated paddy straw, the amount of hemicelluloses and lignin (in % dry
weight) were 20.30 and 20.34 respectively and the total reducing sugar was estimated to be 5.40 mg/g.
Extracellular xylanase and ligninases of P. eous could reduce the amount of hemicelluloses and lignin to 16 and
11(% dry weight) respectively, by 21st day of cultivation. Growth of mushroom brought a seven fold increase in
the total reducing sugar yield (39.20 mg/g) and six fold increase in the production of ethanol (6.48 g/L) after
48hrs of fermentation, when compared to untreated paddy straw
Description:
International Journal of Applied Biology and Pharmaceutical Technology,vol 3,issue 1:jan-mar 2012
Padma, Nambisan; Jasmin, Koshy(IJPAES, April 5, 2012)
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Abstract:
Bioethanol is a liquid fuel obtained from fermentation of sugar/starch crops. Lignocellulosic
biomass being less expensive is considered a future alternative for the food crops. One of the main
challenges for the use of lignocellulosics is the development of an efficient pre-treatment process.
Pretreatments are classified into three - physical, chemical, and biological pretreatment. Chemical process
has not been proven suitable so far, due to high costs and production of undesired by-products.
Biologically, hydrolysis can be enhanced by microbial or enzymatic pretreatment. Studies show that the
edible mushrooms of Pleurotus sp. produce several extracellular enzymes which reduce the structural and
chemical complexity of fibre. In the present study, P. ostreatus and P. eous were cultivated on paddy straw.
Spent substrate left after mushroom cultivation was powdered and used for ethanol production.
Saccharomyces sp. was used for fermentation studies. Untreated paddy straw was used as control.
Production of ethanol from P. ostreatus substrate was 5.5 times more when compared to untreated paddy
straw, while the spent substrate of P. eous gave 5 times increase in ethanol yield. Assays showed the
presence of several extracellular enzymes in the spent substrate of both species, which together contributed
to the increase in ethanol yield
Description:
International Journal of Plant, Animal and Environmental Sciences,vol 2,issue 2,april-june 2012