Biological Study of protease produced by clinical isolates of Staphylococcus aureus

Abstract

The bacterial isolates were obtained from Al-Kindi Hospital were diagnosed by the Vitek-2 system and re confirm by 16srRNA gene as S. aurous, the results were shown 20 isolates (66.7%) out of 30 isolates were positive to protease production. All bacterial isolates (100%) were sensitive to Gentamicin and Levofloxacin. but resistant (100%) to aztreonam. The best temperature for enzyme production from bacteria was 37 °C, and the best pH for enzyme production was 7. Partial purification of the bacterial enzyme (protease) was carried out using short steps included ammonium sulfate 65% saturation, ion exchange using DEAE- cellulose column and then applied on gel filtration chromatography using Sephadex G-200 column. The enzymatic activity was determined for each purification step. The specific fold and yield of the purified enzyme were 5.91 and 38.3 % respectively. The molecular weight of the purified enzyme was 37 kDa , it was determined by SDS-PAGE. After being exposed to high concentrations of the protease enzyme (800-1000 µg/ml), the proliferation of a breast cancer cell line (MCF-7) was seen to be suppressed, however the inhibitory effect gradually diminished as the concentration of the enzyme decreased. 200–400 µg/ml is the recommended concentration.