Keratinase technology: from feather degradation and feed additive,to prion destruction.

Abstract

Abstract A bio-process called thermophilic anaerobic digestion that converts poultry waste into biogas energy was developed in our laboratory. During operation, feathers in the waste were completely degraded. This observation prompted a series of studies that have led to new technology and commercial developments. A feather-degrading bacterium was discovered and isolated. An enzyme called keratinase capable of hydrolysing the feather protein keratin was purified. The gene encoding this enzyme was isolated and sequenced. Genetic modification enabled the over expression of the gene in the parent strain as well as in other Bacillus strains. Scale-up fermentation, first in 150 l and then in 50 kl fermentors, made the mass production of the enzyme possible. Subsequently, in application research, keratinase was shown to partially hydrolyse feathers and convert them into a digestible feed protein. When supplemented as a feed additive on standard diet, the enzyme promoted chicken growth by improving dietary protein digestibility. Ifcommercially developed, keratinase can lower feed cost, increase poultry meat yield, and upgrade the utilization of less digestible protein feedstuffs. From an environmental point of view, keratinase has the potential to reduce waste nitrogen excretion by farm animals. More recently, keratinase was found to be able to degrade prion protein that is believed to cause transmissible spongiform encephalopathies (TSE) including ‘mad cow disease’, sheep scrapie, deer chronic wasting disease and human Creutzfeldt–Jakob disease. This discovery indicated the potential use of keratinase in a new enzymatic process to destroy prion protein and possibly prevent TSE, in a cost-effective and environmentally friendly manner. To test and to develop the enzymatic process, a prion-like surrogate protein (PSP) has been developed as a safe bio-marker. The combination of keratinase and PSP can provide a useful toolbox for TSE prevention. Based on the keratinase platform technology and its applications, BioResource International (BRI), a biotechnology company, was founded to serve the poultry and animal industries.