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Xylanase is a major enzyme used in the paper and pulp industries for biobleaching applications. There are possibilities for xylanase with better properties suitable for industrial applications. This paper focused on a potential xylanolytic fungus, Trichoderma viride VKF-3, obtained from a mangrove soil sample. Optimum conditions for xylanase production were tested by culturing T. viride VKF3 under varying carbon and nitrogen sources, medium pH, and incubation temperature. The isolate T. viride VKF3 achieved a maximum of 3.045 IU/mL of xylanase activity by utilizing coconut oil cake as a substrate. During purification, 84% yield was obtained with 40% ammonium sulphate. The enzyme activity was confirmed through zymogram analysis, and a band was observed at 14 kDa. The xylanase facilitated maximum hexenuronic acid release with a 30% enzyme dosage following 4 h of incubation. Moreover, the Kappa number tended to decrease with increased enzyme dosage and incubation time. There was a Δ brightness of 11% following 4 h of enzymatic treatment. Strength properties, such as the tensile, burst indices, and folding endurance, was improved during the xylanase assisted deinking of pulp. Hence, the present xylanase was found to be suitable for the biobleaching of newspaper waste via an eco-friendly process. [ABSTRACT FROM AUTHOR]

Cellulase is one of the most widely distributed enzymes with wide application. They are involved in conversion of biomass into simpler sugars. Cellulase of Trichoderma longibrachiatum, a known cellulolytic fungus was compared with Clostridium thermocellum [AAA23226.1] cellulase. Blastp was performed with AAA23226.1 as query sequence to obtain nine similar sequences from NCBI protein data bank. The physicochemical properties of cellulase were analyzed using ExPASy's ProtParam tool namely ProtParam, SOPMA and GOR IV. Homology modeling was done using SWISS MODEL and checked quality by RMSD values using VMD1.9.1. Active sites of each model were predicted using automated active site prediction server of SCFBio. Study revealed instability of cellulase of two eukaryotic strains namely Trichoderma longibrachiatum [CAA43059.1] and Melanocarpus albomyces [CAD56665.1]. The negative GRAVY score value of cellulases ensured better interaction and activity in aqueous phase. It was found that molecular weight (M. Wt) ranges between 25-127.56 kDa. Iso-electric point (pI) of cellulases was found to be acidic in nature. GOR IV and SOPMA were used to predict secondary structure of cellulase, which showed that random coil, was dominated. Neighbor joining tree with C. thermocellum [AAA23226.1] cellulase as root showed that cellulases of Thermoaerobacter subterraneus [ZP_07835928] and C. thermocellum [CAA4305.1] were more similar to eukaryotic cellulases supported by least boot strap values. Pseudoalteromonas haloplanktis cellulase was found to be the ideal model supported by least RMSD score among the predicted structures. Trichoderma longibrachiatum cellulase was found to be the best compared to other cellulases, which possess high number of active sites with ASN and THR rich active sites. CYS residues were also present ensuring stable interaction and better bonding. Hydrophilic residues were found high in active sites of all analyzed models and template.