Identification and Antibacterial Activity of Streptomyces mediolani CF51DZ Isolated from the Beetle (Protaetia morio), Collected from Souk Ahras, North-East of Algeria

Abstract

In this study, an Actinomycetota Streptomyces mediolani strain CF51DZ was isolated from a beetle Protaetia morio collected in a cork oak forest in northeast Algeria, to extract, purify and characterize the antibacterial compound. The strain was isolated in specific ISP culture media, identified via morphological, biochemical, physiological and molecular characteristics and then studied its antibacterial activities against pathogenic bacteria using the well diffusion technique. The extraction, purification and characterization of the bioactive compound was carried out using chromatographic and spectroscopic methods. Morphological, physiological, and biochemical properties, as well as the 16S ribosomal DNA sequence of the strain, were found close to those of Streptomyces mediolani. The isolated strain produced an active compound having potent antibacterial properties against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. This compound was isolated and purified with thin layer chromatography and high-performance liquid chromatography, and chemically identified by mass spectroscopy and NMR spectroscopy. In addition, the chemical structure elucidation of the antibacterial metabolite by APCI-MS analysis revealed a peak at m/z 375 [M+H]+, a molecular formula of C19H18O8. This compound was identified as methyl rosarinate: 3-(3,4-dihydroxyphenyl)-1-methoxy-1-oxopropan-2-yl (E)-3-(3,4-dihydroxyphenyl)acrylate based on the IUPAC nomenclature. Moreover, the antibacterial agent was purified from Streptomyces mediolani strain CF51DZ that was for the first time, in Algeria, isolated from the beetle Protaetia morio. This supports further characterization of this promising chemical to ensure the best use for antibacterial applications.