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EVALUATION OF DIFFERENT PHYSICO-CHEMICAL AND BIOLOGICAL PRETREATMENTS FOR ENZYMATIC HYDROLYSIS OF HARDWOOD FOR ETHANOL PRODUCTION

KrishiKosh

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Title EVALUATION OF DIFFERENT PHYSICO-CHEMICAL AND BIOLOGICAL PRETREATMENTS FOR ENZYMATIC HYDROLYSIS OF HARDWOOD FOR ETHANOL PRODUCTION
 
Creator KAUSHAL, RICHA
 
Contributor SHARMA, NIVEDITA
 
Subject enzymes, productivity, fungi, fermentation, cellulose, bacteria, wood, polysaccharides, alcohols, poultry equipment
Hardwood , Potential Microorganisms
 
Description ABSTRACT
In the present investigation, an attempt was made to utilize hardwood as substrate for its degradation by potential
microorganisms and evaluated different pretreatments to enhance their rate of hydrolysis - a key step for its
bioconversion to ethanol. In total 20 microorganisms including 17 bacteria and 3 fungi were isolated. Among
them, SD5 and RS2 were screened for cellulase and SD8 for xylanase production and were identified as B.
simplex SD5, B. subtilis RS2, B. subtilis SD8 by 16S rRNA PCR technique and registered with NCBI under
accession no KF844070, KF844069 and KF844068, respectively. Among fungi, WF5 and RF1 were selected for
enzyme production and were identified using ITS 5.8S rRNA technique as T. harzianum WF5 and R. oryzae RF1
and registered under accession no. KF844067 and KJ1921199, respectively. Cellulase and xylanase enzymes
were optimized through classical approach one factor at a time (OFAT) and Response surface methodology
(RSM) varying medium, pH, temperature, inoculum size, incubation time, and substrate concentration. The
partial purification of hydrolytic enzymes was done by ammonium sulphate precipitation. Full length gene
sequences of BsSD8-xylanase of B. subtilis SD8 and four GHs namely three subunits of cellulase, Endoglucanase
(ThWF5-Endo-glucanase), Exo-glucanase (ThWF5-Exo-glucanase) and -glucosidase (ThWF5-
Glucosidase), and xylanase (ThWF5-Xylanase) of T. harzianum WF5 were pulled out and characterized. To
reduce the production cost of ethanol, cheap untreated and pretreated lignocellulosic forest biomass i.e.
hardwood were used as a substrate for sugar production. Among different hardwood species used, Eucalyptus
and P. deltoides wood were selected for saccharification by bacterial and fungal hydrolytic enzymes,
respectively. Among different physical, chemical and biological pretreatments, H2SO4 + H2O2 + steam
pretreatment was found best for sugar production. Bioconversion of H2SO4 + H2O2 + steam pretreated E.
teretecornis and P. deltoides wood to ethanol was studied under two different fermentation processes i.e separate
hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF). Different
protocols had been designed to delimit the constraints of fermentation process. SHF was evaluated by modifying
four different sub-processes of non-detoxification and detoxification as well as nonpooling and pooling of
pretreated liquor. Maximum ethanol was achieved in protocol IV i.e. 7.02 g/l by co-culture of S. cerevisiae I + P.
stipitis in E. teretecornis wood and 15.62 g/l in P. deltoides wood with fermentation efficiency of 61.05%. Scale
up of SHF with P. deltoides wood using fungal enzymes and co-culture of S. cerevisiae I + P. stipitis was
performed in 7.5 L bioreactor, achieving highest ethanol production after 52 h of fermentation. Among SHF and
SSF, SHF in protocol IV i.e. pooled sample followed by detoxification was found to be the best and in case of
strains used for fermentation, co-culture of S. cerevisiae I + P. stipitis was observed the best combination for
highest bioethanol production
 
Date 2016-06-16T10:57:43Z
2016-06-16T10:57:43Z
2015
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/67443
 
Language en
 
Format application/pdf