A biological study of chitinase produced by clinical isolates of Pseudomonas aeruginosa and detection of ChiA responsible gene

Abstract

All isolates in this study were diagnosed as P. aeroginosa according to the 16srRNA gene. Only two isolates were produced chitinase on chitin agar medium and were positive to the chiA gene. Most of the isolates exhibited high sensitivity (95%) and (90%) to Imipenem and Carbenicillin, respectively, and the resistance to Amoxicillin + Clavulanic acid was shown (80%), while revealed a variable degree in their response to others antibiotics. The crude extract activity and specific activity for extracted chitinase enzymes were 33 U/ml and 18.644U/mg, respectively. The enzyme was purified by different steps include: precipitating with saturation 70% of ammonium sulfate and then applied on ion-exchange chromatography using DEAE- cellulose column and then employ the Sephadex G-200 column for gel filtration chromatography. The purification fold and yield was 28.5%. The molecular weight of the purified enzyme was determined by SDS-PAGE method, and it appeared at 50 kDa. The results of the MTT assay showed that the chitinase has a cytotoxic effect on cancer liver cell lines at a concentration of 100 µg/ml and increased gradually at a concentration of 600 µg /ml, while it showed no or less cytotoxic effect on normal embryonic liver cell line (WRL-68). Chitinase enzyme appeared a higher antibacterial activity at concentration 600 µg/ml and a lower activity at concentration 400 towards clinical isolates of S. aurous and E. coli. The study of histopathological effects was exhibited little morphological changes on cells of liver tissues.