BIOCHEMICAL AND MOLECULAR CHARACTERIZATION OF AN EGYPTIAN MARINE ISOLATE "Alcaligenes faecalis" PRODUCING THERMOSTABLE PROTEASES

An Egyptian marine bacterium, isolated from Hamam Pheroon, South Sinai region was able to produce thermostable proteases, the isolate was identified morphologically, biochemically, and confirmed molecularly by 16S rRNA sequencing with 99% similarity to Alcaligenes faecalis. It exhibited optimum activity of 328.3 U/mg after ten min, incubation at 65C and pH 7. Both ammonium sulphate and sephadex G-100 purification methods enhanced the yield of Alcaligenes faecalis strain HFW-9081 to 125 and 121% as well as the specific activity to 458.9 and 590 U/mg, respectively, compared to cell free supernatant. However, relative protease activity was reduced to 35.8% when H2O2 was added. On the other hand, the activities increased 7.5 folds when Tween-80 was used as a surfactant. Genetic background of the protease genes in Alcaligenes faecalis was analyzed using bioinformatics database for the proteases amino acids sequences in the desired bacteria; and it specified that Alcaligenes faecalis has four different protease genes; these genes encode for various peptidases family groups. The variation in the peptidase family groups provides the protease enzymes with many features making them able to remain active under various environmental stresses. The overall results showed promising thermostable proteases isolated from local marine Egyptian bacterium; that can be used potentially in many industrial applications.