Padma, Nambisan; Jasmine, Koshy(Samanthi Publications, July , 2011)
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Abstract:
Biopulping being less energy intensive, inexpensive and causing lesser pollution, can be a viable alternative to chemical and
mechanical pulping in paper and pulp industry. In view of shrinking forest reserves, agricultural residues are considered as an
alternative raw material for making paper and board. By suitable treatment agriwaste can be converted into substrate for
mushroom cultivation. Mushrooms of Pleurotus sp. can preferentially remove lignin from agriwaste with limited degradation
to cellulose. The present study examines utilization of Pleurotus eous for biopulping of paddy straw by solid substrate
fermentation. SMS, the mushroom growing medium that results from cultivation process, is a good source of fibre and can be
pulped easily. Ligninases present in SMS were able to reduce lignin content to nearly half the initial amount by 21st day of
cultivation. Highest cellulose content (% dry weight) was observed on 21st day, while cellulase production commenced from
28th day of cultivation. SEM images revealed that SMS fibres are still associated with non-cellulosic materials when
compared to chemically (20% w/v NaOH) extracted fibres.
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