Isolation of phytase producer fungi from various sources and thermostable phytase production

Phytase (E.C 3.1.3.8, myo-inozitol hegzakisfosfat fosfohidrolaz), is the enzyme catalyses the hydrolysis of phytic acid to inorganic phosphate and myo inositole phosphate. In recent years, studies have been accelerated on the use of phytate-degrading enzymes in livestock farming and human nutrition in order to make more effective use of phytic acid phosphorus and to reduce environmental pollution. In addition, phytase enzyme is used in the paper industry and soil improvement by preparation of myo-inositol phosphates. The high thermostability of the phytases used as feed additives for preventing feeds from being inhibited at high temperatures during the pelleting phase is one of the most demanded characteristics. To this end, the search for thermostable phytase enzymes has accelerated in recent years. Phytases are defined by many sources such as microorganisms, plants and animals. Among these sources, microorganisms, especially molds, are preferred commercial phytase producers. In this study, 50 thermophilic / thermotolerant fungus were isolated from soil samples and sediment samples collected from hot springs in Aegean region and compost samples taken from mushroom farms and these fungus isolates were identified by polyphasic approach. The phytase activity of 50 isolates was quantitatively determined. 44 of 50 isolates (88%) were determined as active phytase producers. 4.5.37 numbered isolate with the highest specific activity, was selected for further studies. The phytase enzyme of this isolate was produced by fermentation and was concentrated by ultrafiltration. Concentrated enzyme preparation is characterized in terms of optimum temperature, optimum pH, thermal and pH stability, properties of various inhibitors, heavy metals, denaturants, detergents effects, protease stability, effect of various organic solvents and substrate specificity. These characterization and identification studies have shown that phytase enzyme produced by isolate No. 4.5.37, which is identified as Aspergillus tubingensis, is suitable for many conditions in industrial applications such as (activity in a wide range of temperature and pH, thermal and pH stability, stability to metal ions, protease stability, substrate specificity). As a result, Aspergillus tubingensis, 4.5.37 phytase is thought to be an enzyme that can be used as a commercial phytase.