Investigation of phytase production of thermotolerant and thermophilic fungus strains isolated from some hot springs and compost samples in the Aegean Region
Project no. 552 · Status: Kapanmış · 2017
Summary
Phytase (E.C 3.1.3.8, myo-inositol hexakisphosphate phosphohydrolyse) is an enzyme that catalyses hydrolisation reactions of phytic acid to inorganic phosphate and myo-inositol phosphates. Phytases are widely used in human and animal nutrition, aquaculture, soil amendment, and in the production of lower myo-inositol phosphates. High thermostability is the most required characteristic for the feed additive phytases in order to prevent inhibition during the pelleting process at high temperatures. Molds are the preferred commercial phytase producers among the phytrase producing organisms such as microorganisms, plants and animals. In this study, a total of 50 thermophilic/thermotolerant fungal strains have been isolated from 17 different hot springs located in 5 different region and 2 mushroom farms at Aegean Region. Isolates are identified using polyphasic taxonomy and 44 of the isolates (88%) have been quantitavely determined as extracellulart phytase producers. Phytase enzyme of the Aspergillus tubingensis TEM37 strain which have the highest specific activity was produced and concentrated by ultrafiltration. Aspergillus tubingensis TEM37 phytase was found active at a relativeley large range of pH and optimum temperature and pH was determined as 45°C and 2-5.5. Thermostability and pH stability of the enzyme preparation was also found quite high and the preparation protected its activity completely at 100°C for 2h and 83% at pH2-12. Km and Vmax values are determined as 174.36U/ml and 30.3 U respectively. The enzyme preperation have found resistant against many metal ions and increased its relative activity in the presence of Zn+2 and Ba+2 ions. Susbtratre specifity range was also large and D-glucose, D-fructose, ATP, ADP and AMP have been used as subtrates. A. tubingensis TEM37 phytase was showed considerable activity in the pressence of organic solvents and increased its relative activity to 191% with 50% isooctane. The enzyme preparation showed good resistance against proteases and protected 97% and 88% of its initial activity after 2 h incubation with pepsin and trypsin. Furthermore, phytase preparation protected most of its activity in the presence of detergets and denaturants. Consequently, it appears that A. tubingensis TEM37 phytase is an enzyme that can be used in the industry, especially in the preparation of animal feeds.