Biomacromolecules in recent phosphate-shelled brachiopods: identification and characterization of chitin matrix

Abstract Phosphate-shelled brachiopods differ in filter-feeding lifestyle, with Lingula anatina an active infaunal burrower, and Discinisca tenuis a shallow marine epibenthic animal. The shells of these animals are built organophosphatic constituents, the organic fibres/sheets reinforced calcium phosphate to provide sophisticated ultrastructural robustness. This investigation examined nature fibres order improve understanding how living organisms produce hierarchically structured biomaterials. Unlike powdered samples commonly used previous studies, were isolated for first time shell fractions purified, study content biopolymer fibres. Biochemical methods including Calcofluor staining revealed chitin matrix. Ultrastructural analysis, thermal gravimetric spectroscopic analyses show that core polysaccharide framework is composed layers β -chitin sheets and/or fibrils coated fibrous There more matrix L. (26.6 wt.%) compared D. (12.9 wt.%). Taken together, data contributes increased skeletal strength, making highly adapted life as burrower. In comparison, contains less lives attached epibenthos environment. Graphical abstract First evidence β-chitin recent