Test for the production and assay of the enzymatic activity of bacterial and Archean halophilic proteolytic strains isolated from Algerian hypersaline environments

Abstract

The present work was carried out on 133 halophilic strains, isolated on MGM medium at 12 and 23% (w/v) of salt. A screening of the extracellular proteolytic activities, carried out on the same medium supplemented with casein or gelatin at 1% (w/v), allowed us to select 24 bacterial and 21 Archaeal strains presenting a precipitate around the colonies for casein and/or a translucent halo (after addition of Frazier's reagent) for the gelatin. The enzymatic test was done on liquid medium in micro-culture on a 2 mL Eppendorf tube. The assay of the proteolytic activity using Azocasein as substrate, following 2 protocols the first with PBS and the second with Tris HCl, with positive and negative controls, demonstrated interesting results for 10 strains among the 45 tested including 5 bacteria and 5 archaea. These have undergone morphological, physiological and molecular characterization based on amplification and sequencing of the 16S ribosomal RNA gene.