Production and Characterization of Semi-Quinolone Antibiotic Produced by Streptomyces Griseorubens

Abstract

Waleed M. Abdulkhair and Mousa A. Alghuthaymi

This work is an attempt to overcome antimicrobial resistance problem which dispersed worldwide in particular developing countries due to misuse of antibiotics. Actinobacteria were isolated and screened against selected resistant Gram-negative bacteria to detect the powerful antibacterial activity. Identification of the most potent actinobacterial isolate has been carried out using classical and genetical methods. Antibacterial compound has been extracted, purified and characterized using accurate and more specific techniques and instruments. Among forty actinobacterial isolates, only twenty-two isolates could inhibit the growth of Gram-negative bacteria. The most potent isolate Eg-7 was identified as S. griseorubens, which has a typical 16S rRNA gene. The antibacterial compound was extracted using ethyl acetate, and separated by High Performance Liquid Chromatography using methanol and water as a mobile phase. Five active peaks were displayed and retained in the range 40 – 45 min, but the last three peaks were retained at 41.90, 43.43, and 44.54 min, respectively. The crude extract was analyzed by liquid chromatography mass spectrum, where the active peak was displayed at 721.325 m/z. The antibacterial compound was purified using flash column chromatography and gel filtration column chromatography. The active fraction was analyzed by Infra-Red spectrum, where a broad absorption at 3338 cm-1 was displayed. Molecular formula of an antibacterial compound was determined by mass spectrum as C35H26N6O4. Nuclear magnetic resonance analysis was carried out for an antibacterial compound. These results suggest that a new antibacterial compound that similar quinolone could be produced by S. griseorubens and exhibited a higher activity against Gram-negative bacteria.

PDF