Phytase-Producing Bacteria from Extreme Regions in Indonesia

ABSTRACT

In this study, 154 isolates capable of producing extracellular phytate-degrading activity were isolated from four soil samples from volcanic areas in Central Java, Indonesia. Six strains with high phytate-degrading activity were selected for strain identification and characterization of the corresponding phytate-degrading enzyme. Blast analysis of 16S rRNA gene sequences revealed high similarities for all the six isolates to reference sequences belonging to the genus Bacillus. Isolates MS5, MC6, D10 and D16 showed 99% sequence identity to B. cereus, while isolate MC8 exhibited 99% sequence identity to B. aryabhatti and D6 99% sequence identity to B. psychrotolerans. The crude extracellular phytase preparations from the isolates showed following optimal conditions for phytate dephosphorylation: pH 4.0 and 50°C (isolate D10), pH 5.0 and 60°C (isolate MC6, and isolate MS5), pH 6.0 and 50°C (isolate D16) and pH 6.0 and 60°C (isolate D6) and pH 6.0 and 40°C (isolate MC8). Zn2+ and Fe3+ strongly inhibited phytate dephosphorylation with all phytase preparations studied. In the presence of Ca2+, an increase in phytase activity of 10-15% was obtained.

Key words:
16S rDNA, Bacillus sp.; bacterial phytase; phytate; phytate-degrading enzyme