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A brief review has been presented on the existing methods to enhance the durability of lignocellulosic fibers (LCFs) for manufacturing composites for engineering applications. The free hydroxyl groups of the cellulose chains within LCFs tend to attract water molecules in moist environment, which may cause the fibers to swell and the cellulose chains to lose their integrity due to hydrolysis and oxidation imparted by the actions of biogenic enzymes or chemical factors, such as acidity, alkalinity, and salinity or UV irradiation. This study mainly highlights those technologies that present the modifications of cellulose main chain within the LCFs to improve the degradation resistance and mechanical strength. Detailed pros and cons of those chemical modifications have also been presented in this study with possible applications of the composites with special reference to durability.

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Chitin is a linear homo-polymer of N-acetyl-D-glucosamine (GlcNAc) and the second most abundant biopolymer after cellulose. Several industries rely on the bioprocesses for waste chitin recycle and hydrolysis by chitinase (EC 3.2.1.14) for potential healthcare applications through the production of its monomeric subunit, GlcNAc. In the present study, a chitinase-producing fungus (named as MFSRK-S42) was isolated from the marine water sample of North Bay of the Andaman and Nicobar Islands. It was identified as Aspergillus terreus by morphological and molecular characterization methods leveraging the internal transcribed spacer between 18S rRNA and 5.8S rRNA. Chitinase that was isolated from the fermentation broth of marine Aspergillus terreus was used to carry out biotransformation of chitineaceous wastes. Prior to the enzymatic hydrolysis step, chitins from different sources were characterized for the presence of characteristic functional groups, grain size distribution, and surface morphology. Enzymatic hydrolysis of 50 mg/ml substrate with six units of enzyme incubated for 5 days revealed 15, 36.5, 40, and 46 mg/ml GlcNAc production from ground prawn shell, chitin flakes, colloidal prawn shell, and swollen chitin respectively under standardized conditions, as determined by HPLC. In this study, 30, 73, 80, and 92% GlcNAc yields were observed from ground prawn shell, chitin flakes, colloidal prawn shell, and swollen chitin conversion respectively. The HPLC-eluted product was confirmed as GlcNAc by the presence of characteristic functional groups in FTIR and 244 Da molecular weight peak in HRMS analyses.

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