A bacterial isolate, Alcaligenes sp. secreting phytase (EC 3.1.3.8), was isolated and characterized. The optimum conditions for the production of phytase included a fermentation period of 96 h, pH 8.0, and the addition of 1% (w/v) maltose and 1% (w/v) beef extract to the culture medium. This enzyme was purified to homogeneity and had an apparent molecular mass of 41 kDa. The optimum pH range and temperature for the activity of phytase were found to be 7.0-8.0 and 60°C, respectively. This enzyme was strongly inhibited by 0.005 M of Mn2+, Mg2+, and Zn2+. In vitro studies revealed that the phytase from Alcaligenes sp. released inorganic phosphate from plant phytates. Phytase released 1930？±？28, 1740？±？13, 1050？±？31, 845？±？7, 1935？±？32, and 1655？±？21 mg inorganic phosphate/kg plant phytates, namely, chick pea, corn, green pea, groundnut, pearl pea, and chick feed, respectively. 1. Introduction Phytate-degrading enzyme (phytase, EC 3.1.3.8) preparations have a wide range of applications in animal and human nutrition. Besides that, these enzymes have also attracted considerable attention from both scientists and entrepreneurs in the areas of environmental protection and biotechnology. Phytases are of great interest in biotechnological applications, in particular for the reduction of phytate content in feed and food [1]. Phytases are capable of initiating the stepwise release of myoinositol and phosphoric acid, leading to the formation of myoinositol phosphate intermediates from phytate [2]. Most plant-origin foods have from 50% to 80% of their total phosphorus as phytate [3]. Phytate chelates essential minerals, binds to amino acids and proteins, inhibits digestive enzymes, and decreases the nutritive value of food [4]. Monogastric animals poorly utilized phytate-bound phosphorus, due to insufficient phytate-degrading activity in the gut [5]. Therefore, hydrolysis of phytate is desirable for releasing valuable nutrients for beneficial utilization. The addition of phytate-degrading enzymes can improve the nutritional value of plant-based foods by enhancing protein digestibility and mineral availability through phytate hydrolysis during digestion in the stomach or during food processing [6], thus reducing the phosphorus excretion of animals [7]. Only a limited number of bacterial phytases have been reported and studied [8]. Phytase has been isolated from bacteria such as Escherichia coli [9], Pseudomonas sp. [10], anaerobic rumen bacteria, particularly Selemonas ruminantium, Megasphaera elsdenii, Prevotella sp., Mitsuokella multiacidus [11], and Raoultella sp.
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