A comparative study on permeabilization treatments for in situ determination of phytase of Rhodotorula gracilis

Rhodotorula gracilis, a red yeast, was
shown to produce phytase and the cultural conditions were standardized for
phytase production. Permeabilization treatments using detergents, organic solvents,
enzymes and physical methods were performed and compared by measuring the phytase
activity of whole cells. None of the permeabilization methods except the freeze-thaw
method enhanced phytase activity. The enzyme activity of a yeast suspension
subjected to 15 cycles of freezing and thawing was 77·26 U g�1 cells. Phytate in feeds
is an anti-nutritional factor which complexes with many minerals, rendering it
unavailable to monogastric animals. Rhodotorula gracilis subjected to freeze-thawing can
be used as a source of phytase in feeds to enhance phosphorus availability.