Solid-state fermentation of phytase from cassava dregs.
Phytases produced by numerous microorganisms and plants degrade phytic acid that has chelated with metal ions in food and feed. It is important to study phytase for the role of metal ions in nutrition of animals and humans as well as in the reduction of organic phosphate content of aqueous environment. This article reports on solid-state fermentation of phytase from a new substrate of cassava dregs. Large quantities of cassava dregs are produced in tropical areas as a byproduct of cassava starch processing. Protein and inorganic salts were found to be low in cassava dregs. Cassava dregs could be employed for phytase synthesis after the addition of a nitrogen source and mineral salts. Ammonium nitrate was the best nitrogen source among the nitrogen sources investigated, including beef extract, yeast extract, urea, ammonium nitrate, sodium nitrate, and ammonium sulfate. Sodium dodecyl sulfate promoted phytase production from cassava dregs. A maximum phytase yield of 6.73 U/g of dry mass was obtained. The obtained phytase was stable at feed-processing temperature, since 70% of initial enzyme activity was maintained after 30 min of treatment at 75 degrees C.
Hong
K
K
Key Lab of Plant Protection Research Institute, National Key Biotechnology Laboratory for Tropical Crops, Chinese Academy of Tropical Agricultural Sciences, Chenxi, Haikou, Hainan. hongk@public.dzptt.hi.cn
Ma
Y
Y
Li
M
M
D010832:6-Phytase / Q000096:biosynthesis* / Q000737:chemistry; D000821:Animal Feed; D000818:Animals; D001234:Aspergillus niger / Q000201:enzymology / Q000254:growth & development; D004795:Enzyme Stability; D005285:Fermentation; D005511:Food Handling; D006801:Humans; D007220:Industrial Waste; D002365:Manihot; D013696:Temperature
D007220:Industrial Waste; D010832:6-Phytase