NeemishaGurshinderdeep Singh2021-09-102021-09-102020Gurshinderdeep Singh (2020). Assessment and development of microbial biofilms for efficient degradation of paddy straw (Unpublished M.Sc. thesis). Punjab Agricultural University, Ludhiana, Punjab, India.https://krishikosh.egranth.ac.in/handle/1/5810175602An experiment was conducted to assess the potential of lignocellulolytic microorganisms and their biofilms for paddy straw degradation. Fifty four fungal and 10 bacterial cultures were screened qualitatively on the basis of zone formation for cellulolytic (31 cultures,0.2-5.1cm), hemi-cellulolytic (13 cultures,0.3-1.8cm) and lignolytic activities (15 cultures,0.2-1.8cm). Quantitatively, during submerged and solid state fermentation, highest cellulase and laccase activities were obtained by culture17 (0.709IC/ml and 0.666IU/ml), and Lignin7 (0.821CU/ml and 3.919CU/ml), whereas, highest xylanase activity was observed in culture F2C5 (0.840IU/ml) and L1C8 (1.555IU/ml), respectively. On the basis of functional properties and growth characteristics, 11 lignolytic, 10 cellulolytic and 9 xylanolytic cultures were used for interaction studies. After testing for compatibility, cellulolytic (Culture17&Compost fungus), xylanolytic (F2C5&L1C8) and lignolytic fungi (Lignin7&White4) were selected for biofilm formation. Under laboratory conditions, the biofilms were used for paddy straw degradation and treatment T14(Bacillus subtilis+CF1+CF2+XF1+XF2+LF1+LF2) showed best results after 30&60 days for reducing cellulose (28.9&24.1%), hemicellulose (16.6&13.4%) and lignin (6.8&5.8%) content of paddy straw. The effect of sequential addition of cellulolytic, hemi-cellulolytic and lignolytic cultures on paddy straw degradation was tested for 21 days in which treatment B14 resulted in highest decrease in cellulose (32.8%), hemicellulose (24.3%) and lignin (7.3%). The best biofilm was further evaluated using different N and C sources and treatment T7 supplemented with ammonium sulphate@0.5% and jaggery@1% was found to be most effective in degrading the paddy straw. A significant reduction was observed in cellulose (26.0%), hemicellulose (31.2%) and lignin (44.4%) content as compared to 9.4%, 6.8% and 22.6% in control, respectively.EnglishThesis