微生物および生化学技術ジャーナル

概要

How Microbes helped solve a Complex Biomechanical Problem associated with Bird Flight

Theagarten Lingham-Soliar

Bird feathers are made of the toughest natural elastomeric biopolymer, β-keratin. The almost inextricable bond between the fibre and matrix texture of β-keratin has made it virtually impossible to ascertain a fibre hierarchy in the main support structures of the feather, the rachis and barbs, other than filaments nanometres in diameter thick. To circumvent the limits of conventional structure-determination methods microbes were used for the first time to help resolve a biological structural problem. Naturally occurring feather parasites, fungi, were allowed to grow in feathers under laboratory conditions, the hypothesis being that they would preferentially degrade the matrix and release the fibre components. The result was that microbes revealed for the first time the true feather microfiber hierarchy, which included the thickest fibres known in β-keratin by a magnitude of three. These fibres were named syncytial barbules because they showed a system of intermittent nodes as in free down feathers. The side walls of the rachis and barbs were similarly investigated and revealed a crossed-fibre system seen for the first time in feathers. Both discoveries have profound biomechanical significance including a high work of fracture in the feather.