Isolation and molecular characterization of phytase producing actinobacteria of fruit orchard

Abstract

In the present investigation, the screening of rhizospheres of fruit orchard was carried out to investigate phytase producing actinobacteria. Out of 52 strains, isolated in different orchards, four isolates SK701, SK702, SK704 and SK705 were scored with phytate-degrading activities of different levels. These strains, on investigation at morphological, cultural, biochemical and molecular levels using 16S rRNA gene were found to belong to Streptomyces and Nocardiopsis species. Phytase producing actinobacteria Streptomyces species strain SK702 and Nocardiopsis species strain SK705 were finally screened on phytase specific medium on the basis of distinct peripheral halo region. They were further analyzed in broth culture using sodium phytate as substrate. Among them, strain SK705 was selected as the best producer (>350 U/mL after 96 h of culture). This phytase showed optimal activity at pH 5.5 and 35 °C, demonstrating appropriate characters for application in feed of several industrial processes. Phytase production was found maximum on 4–5th day when pH value was also decreased to 5.6 indicating production of organic acid. Blast homology of 16S rRNA gene sequence of isolate SK705 identified 99% similarity with Nocardiopsis sp. HW80 but the difference of 14 nucleotides out of 1387 conferred a separate NCBI accession no. KF280241. We propose the name for this distinct species as Nocardiosis umakantae SK75L. All these data provide promising prospects of the use of this novel strain with phytase production in food industry.