A protein discovered in squid teeth might someday be responsible for a significant reduction in the current global plague of microplastic pollution, especially in the planet's oceans.
In a paper published February 21 in Frontiers in Chemistry, lead authors Abdon Pena-Francesch and Melik C. Demirel, both from Pennsylvania State University, reviewed properties of fibres and films—and their possible applications—inspired by proteins derived from teeth found in squid arms.
Squid—which are found in all of the Earth's oceans and which range in size from the one-gram pygmy squid to the school-bus-sized giant squid—have two long tentacles and eight smaller arms. The tentacles are used to grab prey, and the arms are used to control and hold its food while the cephalopod cuts bite-size chunks with its sharp central beak. The arms are covered with suction cups to aid in this function, and in some squids each cup is ringed with sharp teeth.
These teeth are composed almost entirely of protein that can be fashioned into biodegradable items with a wide range of possible applications, including as a protective ultrathin coating for synthetic plastic-based fibres such as polyester, acrylics, and nylon, which make up about 60 percent of all clothing manufactured today.
When these fibres get abraded and break down during the washing proces, the tiny pieces (less than five millimetres in size) released into the water and, ultimately, flushed into the oceans become a large percentage of microplastics that persist in the environment for hundreds or thousands of years, ultimately being taken up by and accumulated in marine organisms as small as zooplankton and as large as whales.
Tests have shown that protective films made from them and used to coat microfibres resisted mechanical abrasion and may significantly prevent loss of particles into the environment.
Various manufacturing processes and the cosmetics industry are also significant sources of microplastics pollution.
Toxic chemicals used in the manufacture of plastics, some of which are carcinogenic, are of concern when humans consume fishes and other marine organisms.
Happily for squid, the proteins found in squid-ring teeth are easily and cheaply synthesized.
As researcher Demirel told Frontier Science News today (February 22): “We don’t want to deplete natural squid resources and hence we produce these proteins in genetically modified bacteria. The process is based on fermentation and uses sugar, water, and oxygen to produce biopolymers."