Abstract

HALOCIN PRODUCTION FROM HALOARCULA HISPANICA, A SALTERN EXTREMOPHILE

J. Sujatha and J. Esther Jasmine

ABSTRACT

The present study was focused on production of halocin, a peptide antibiotic. Five strains (Haloarcula hispanica, Haloarcula marismortui, Haloarcula vallismortis, Halobacterium salinarum and Halofferax larseni) of extremely halophilic archaea strains isolated from parangipettai saltpans and used in present study. Haloarcula hsipanica which showed highest antagonistic activity was selected for further study. The different pH, temperature, salinity, carbon sources, nitrogen sources and incubation period were tested for the optimal production of halocin. The maximum halocin activity of 5210 AU was recorded in shake flasks. The antimicrobial activity of halocin from Haloarcula hispanca disappeared when incubated with proteinase K and trypsin proved that the inhibitory substance was a protein. The partially purified halocin from Haloarcula hispanica showed varied activity against five of tested pathogens and maximum activity was found against Escherichia coli (10mm) and minimum against Salmonella paratyphi (3mm). Against Klebsiella oxytoca and Klebsiella pneumoniae it did not show any activity. The partially purified halocin found to be 32kDa protein on SDS-PAGE analysis. Hence the present study proved that salterns harbor hlophilic archaea and halophilic eubacteria and was capable of producing halocin, a peptide antibiotic.

Keywords: Halocin, Antibiotic, Haloarcula hispanica, Antagonistic activity, Escherichia coli.