ChiBio: An Integrated Bio-refinery for Processing Chitin-Rich Bio-waste to Specialty Chemicals

Chitin is the second most abundant biopolymer on earth, next to plant-derived celluloses. It can be found in fungi, insects, and crustacean shells. The processing of crustaceans (e.g., shrimps and crabs) in the EU alone results in more than 100,000 tons of shell waste each year. Chemically, chitin is distinguished from cellulose just by an additional acetamide function on many of its 1.4-β-linked hexose monomer units. In contrast to lignocellulosic biomass and despite its unique chemical features, conversion strategies for chitin-rich biomass to value-added products are at present basically limited to chitosan utilization, although chitin has a huge potential for bio-based materials as well as chemicals. Especially for European shell waste, the high sodium carbonate content makes its usage challenging. In addition current processing methods require harsh chemical conditions. Therefore, with “ChiBio” a bio-refinery concept was recently developed within an EU-funded project, combining a sustainable chitin demineralization process by microorganisms and an enzymatic degradation of the biopolymer into its basic building blocks, N-acetylglucosamine and glucosamine. For the demineralization step, natural microbial isolates as well as Serratia spp. and Lactobacillus spp. were used in fermentations, realizing a demineralization grade of 97%. Chitin-degrading enzymes from Serratia marcescens, Amantichitinus ursilacus, and Andreprevotia ripae were overexpressed and used as enzyme cocktails to degrade chitin with yields up to 95%. The resulting monomers could finally be used for the production of novel bio-based polymers and all biological by-products accumulating in this process chain, e.g., proteins and lipids could be used as feed for biogas production. Overall, ChiBio is about novel tools, novel processes, and novel product portfolios to create value out of chitin-rich bio-waste products.