Dr. Gurvinder Singh KocherReddy, Kandukuri Thanuja2024-05-312024-05-312024Reddy, Kandukuri Thanuja (2024). Pretreatment studies on corn cobs using greensolvents and fungal lignolytic enzymes (Unpublished M.Sc. thesis). Punjab Agricultural University, Ludhiana, Punjab, India.https://krishikosh.egranth.ac.in/handle/1/5810209569The purpose of the current study was to standardize and evaluate an effective procedure particularly among green solvents (Acetic acid @40%; H2O2-Acetic acid mixture 1:1 ratio) and biological methods for pretreating corn cobs followed by their saccharification. The proximate analysis of the grounded and dried maize cobs(500µ) revealed their biochemical composition as cellulose (36%), hemicellulose (28.6%), lignin (10.4%), and ash (2.1%). Different concentrations of corn cobs (5,10 & 15 % w/v) were subjected to acetic acid @40% and HPAC pretreatments. Among 5-15%(w/v) samples of 40% acetic acid pretreatment and HPAC pretreatment, 10%(w/v) sample showed a better delignification of 82.1% along with higher availability of cellulose and hemicellulose contents (34.5% and 28.5%, respectively) and 5%(w/v) sample resulted in higher delignification of 84.8% along with higher availability of cellulose and hemicellulose contents (30.5% and 23%), respectively. For biological pretreatment of corn stover, a two membered fungal consortium of strains viz. Pleurotus florida PAU22-01 and Phanerochaete chrysosporium MTCC787, already screened for ligninolytic enzyme production in our laboratory, was used with corn cobs as substrate on lignin modifying enzyme (LME)- basal medium (LBM). It was observed that maximum enzyme activity (U/ml) was present on 10th day as 39.9, 46.4 and 58.2 for laccase, LiP and MnP, respectively. The ligninolytic enzyme production was scaled upto 3000ml and the crude extract was concentrated to 200 ml having enzyme activities (U/ml) of 116.53, 121.6 and 88.94 for Lacc, LiP and MnP enzymes, respectively which was partially purified by Fast Protein Liquid Chromatography (FPLC) technique. The pretreatment of corn cobs (1.25g, 2.5g and 5g) using partially purified enzyme (8 ml enzyme volume in a final mixture of 30 ml) resulted in maximum delignification of 78.4% for 2.5 g pretreated sample with increase in cellulose availability from 28.65% (untreated) to 31.1% (pretreated) with corresponding total sugars, reducing sugars and xyloses of 44.9, 19.3 and 12.3 mg/gds, respectively without formation of furfurals. Among all the above mentioned pretreatments, HPAC pretreatment was found to be most efficient. The saccharification of pretreated (organosolv and biological) corn cobs at different concentrations (1.0-2.5g) with commercial cellulase loading of 30 FPU/gds, resulted in maximum release of reducing sugars at 2g percent of pretreated corn cobs. Correspondingly, the saccharification efficiencies of 71.4% and 97.1% [2.0g @72 h] were recorded for 40% acetic acid and biological pretreatments, respectively.EnglishThesis