Production and characterization of phytase from Streptomyces luteogriseus R10 isolated from decaying wood samples

Abstract

Microorganisms are the richest source of phytase which catalyze hydrolysis of phytate to myo-inositol and phosphate. 50 Actinomycete isolates were isolated from heated soil, sand, wastewater, animal faces and some plant ecological wastes on Starch nitrate agar containing 15 μg / mL of antibiotics (Tetracycline + Amphotericin B, w/w). Out of 50 Actinomycetes isolates, 20 isolates (40%) produced extracellular phytase enzyme on solid medium containing wheat bran as carbon source. In liquid medium, the phytase activity was measured as U/mL and the most active isolate in phytase production was R10. Using morphological, physiological and biochemical studies, it was identified as Streptomyces sp. Using 16S rDNA analysis, it was identified as S. luteogriseus R10. Growth in medium containing 1% Na-phytate (pH 6.5) at 40°C for 7days increased phytase production. The maximum phytase activity was achieved using wheat bran, straw, rice husk and hay after seven days of incubation at 40°C but low activity was obtained using Sawyer and baggage as a carbon source. The molecular weight of the purified phytase is 65 kDa and it exhibits optimum activity at pH 5 and 45°C. All tested metal ions at 10 mM enhanced phytase activity except Ba 2+, Co 2+, Cu 2+, Ag, Fe 3+ and Hg 2+. Improvement of phytase production was carried out using protoplast fusion between S. luteogriseus R10 and S. niveus MM1. Fusant F7 was the best phytase producer (3 time higher) compared to its parents.