Influence of extraction methods on antimicrobial activities of lignin-based materials: A review

Lignin is an abundant biomass-derived polymer that can be utilized as an antimicrobial agent. However, its antimicrobial properties depend on the method used for its extraction. Amongst the extracted lignin, lignin-based materials including nanomaterials are often favoured due to their unique properties and mode of action in suppressing microbial growth by targeting the cell membrane of bacteria. This lignin is generally obtained through chemical extraction from a variety of natural sources using different methods. However, their extraction methods, in relation to their antibacterial properties, have not been well documented. Here, we present an overview of alternative methods of extracting lignin and their potential influence on antimicrobial properties of the lignin. Shortcomings of the extraction methods as well as potential solutions for process optimisation are also discussed.