Potential application of microbial phytase in aquaculture

Phytases are histidine acid phosphatases that catalyze the hydrolysis of phytic acid toinorganic phosphorus and myo-inositol phosphates. The phosphorus that is being released is used invarious metabolic processes. These enzymes are able to promote the growth of animals and plants aswell as increase the nutritional value of feedstuffs through dephytinization. Phytases are widespread innature because they are found in animals, plants and microorganisms. This paper discusses the differentmicrobial phytases that have been characterized and their beneficial roles in aquaculture. In order to beincorporated in the feed, microbial phytases must have the ability to withstand high temperatures duringprocessing, and to be stable in the gastrointestinal tract of the fish, the enzymes must be active at lowpH levels. The various effects of microbial phytases on the bioavailability of phosphorus in fish, ongrowth performance, on the immune responses, on the excretion of phosphorus and on the environmentare also reviewed.