Inducible secretion of phytate-degrading enzymes from bacteria associated with the medical plant Rosa damascena cv. Taifi using rice bran
More than 320 bacteria were isolated from the soil (Rhizosphere, endophyte, flowers and leaves) of Rosa damascena cv. Taifi and screened for phytase activity. Phytase activity was checked for 24 isolates in Bacillus broth media supplemented with and without rice bran. Twelve (12) isolates were found with detectable phytase activities. Among them, four selective bacterial strains were active (BAFA.Taifi94, BAFA.Taifi103, BAFA.Taifi111 and BAFA.Taifi117). The phytase activity of strain BAFA.Taifi111, which was grown in the Bacillus broth media and supplemented without rice bran showed 19.7 units/ml initial growths whereas, with an induction of rice bran 37.7 units/ml was observed after 10 days in the shaker at 30°C/150 rpm. The optimum temperature for BAFA.Taifi94 and BAFA.Taifi103 was 60°C, whereas it was 70°C for BAFA.Taifi111. The stability at 80°C was exhibited by BAFA.Taifi117. The optimum pH range was pH 5-6.5 at 60°C. The obtained Bacillus species for phytase production have been induced using rice bran and their physical properties such as temperature optima, pH optima and thermo stability were found similar to the previously characterized and published or commercially available Bacillus phytases.
Key words: Bacillus sp., phytase activities, soil bacteria, Bacillus broth, Bacillus broth.