New endolysin against Acinetobacter baumannii: antibacterialeffect

Background and Aim : Nowadays, antibiotic-resistant bacterial infections are the second leadingcause of death in the world. Endolysins are the phage enzymes can destroy bacterial cell wall,therefore, they can be used for development of new antibacterial drugs. One of the most importantbacteria causing more than ۸۰% of nosocomial infections is Acinetobacter baumannii. In this studythe antibacterial effect of new recombinant engineered endolysin was investigated against A.baumannii.Methods : For this purpose, designed recombinant endolysin was expressed in E. coli BL۲۱(DE۳)using pET expression system and purified by nickel chromatography column. The column outputchecked by SDS-PAGE to confirm its purity. Then, the protein concentration calculated withBradford method. To investigate the antibacterial effect of the fusion protein, plate lysis assayperformed, on Acinetobacter baumannii PTCC ۱۸۵۵ according to CLSI ۲۰۱۸ protocol. As well,Mueller-Hinton Agar (MHA) medium and Trypticase Soy Agar (TSA) medium were used forantibacterial effect evaluation. Consequently, ۰.۵ McFarland (OD~۰.۱۳) sample was preparedfrom bacterial liquid culture (۲۴h). The bacterial suspension was cultured as dense lawn by sterileswab on TSA and MHA medium. The initial concentration of the recombinant enzyme was ۶۰۰μg/ml, which was diluted ۱:۲ with a suitable buffer containing ۰.۵ mM EDTA as a membranepermeabilizer. ۲۰μl of each sample dropped on the plates and incubated overnight at ۳۷oC.Results : The results showed that recombinant endolysin had a significant inhibitory effect on A.baumannii on TSA plate. In addition, MHA medium, had an inhibitory effect on the enzyme andprevented the formation of zone of inhibition.Conclusion : According to the obtained results, the engineered fusion protein has a good inhibitoryeffect on this bacterium and by further studies for improving its activity it can be considered as apossible new alternative for antibiotics available in market

کلیدواژه ها:

Acinetobacter baumannii ، Anti-Bacterial Agents ، Recombinant Fusion Protein ، Peptidoglycan Hydrolase.