Microbial degradation of paddy straw by submerged state fermentation
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Date
2021
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Punjab Agricultural University, Ludhiana
Abstract
Paddy straw is the most abundant yet ineffectively managed agricultural residue leading to resource wastage and generation of environmental pollution. The action of microbes could help to curb the waste and evolve it to resourceful products. The present study was conducted to evaluate the lignocellulolytic efficiency of microbes for the degradation of paddy straw under submerged fermentation. Six bacterial, one actinomycete and one fungal culture were isolated, purified and screened qualitatively and quantitatively for lignocellulose degrading potential. Three standard lignolytic cultures (Delftia sp. PP4_S3, Bacillus sp. and Pseudomonas sp.) were also used as positive control. A consortium of the isolated and standard culture was used to decompose untreated paddy straw resulting in maximum enzyme activities of endoglucanase (1 U/ml), exoglucanase (1.31 U/ml), β-glucosidase (2.42 U/ml), xylanase (12.63 U/ml) and manganese peroxidase (5.43 U/ml) after 28 days of incubation along with laccase (4.36 U/ml) and lignin peroxidase (6.71 U/ml) after 21 days of incubation. By the action of the consortium, untreated paddy straw showed maximum reduction of 35.31% in cellulose, 22.5% in hemicellulose and 44.72% in lignin after 28 days of incubation. Consortium when used along with 5% urea pretreated straw under submerged fermentation reported maximum enzyme activities for endoglucanase (5.96 U/ml), exoglucanase (6.32
U/ml), β-glucosidase (8.63 U/ml), xylanase (31.78 U/ml) and manganese peroxidase (16.8 U/ml) after 28 days of incubation. Laccase (12.63 U/ml) and lignin peroxidase (27.34 U/ml) activities were found to achieve maxima after 21 days. Pretreatment of paddy straw with 5% urea followed by microbial degradation, reported maximum loss of 29.87% in cellulose, 43.48% in hemicellulose, 35.64% in lignin and 43.65% in dry matter. Field emission scanning electron microscope (FE-SEM) micrographs revealed sufficient sloughing off of cellulose and hemicellulose with profuse growth of microbes without any silica degradation.
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Verma, Ishita (2021). Microbial degradation of paddy straw by submerged state fermentation (Unpublished M.Sc. thesis). Punjab Agricultural University, Ludhiana, Punjab, India.