Wednesday, 27 May 2009
New classes of fungal phytase genes discovered.
Phytase is produced commercially by microbial fermentation using the fungus Aspergillus niger and other micro-organisms. Phytase is an enzyme used in the animal feed industry that enhances the nutritional value of animal feed and diminishes the phosphate burden on the environment. Phytase hydrolyzes phytic acid, which is the principle storage form of phosphorus in feedstocks of plant origin and can not be digested by gastric farm animals such as pigs and poultry. Phytic acid also forms complexes with proteins, digestive enzymes and minerals, and as such is considered to be an anti-nutritional factor.
The use of phytase eliminates the need to supplement feeds with inorganic sources of essential phosphate. Thus, by releasing bound phosphate in feed ingredients, phytase makes more phosphate available for bone growth, and reduces the amount excreted into the environment.
The discovery of the new fungal genes by TNO, is significant for the commercial production of animal feedstuffs. The increasing availability of fungal genome sequences has allowed a genome mining approach to identify the new gene classes. One class is distantly related to known fungal phytases and the other embraces fungal phytases showing a high homology to bacterial phytases. In collaboration with Dyadic NL, these new phytase gene candidates have been expressed in Chrysosporium lucknowense and were shown to be functionally active.