Broad spectrum antimicrobial compounds from the bacterium Exiguobacterium mexicanum MSSRFS9

S.P. Shanthakumar, Purushothaman Duraisamy, Ganga Vishwanath, Benson Chellakkan Selvanesan, Vijayakumar Ramaraj, B. Vasantharaj David

Department of Microbiology and Pest management, M. S. Swaminathan Research Foundation, Taramani, Chennai 600113, India..

Abstract

Clinical bacterial pathogens front a major challenge for the clinical researchers and physicians. In particular microbial pathogens like Escherichia coli, Shigella flexneri, Klebsiella pneumonia and Salmonella enterica are apparelled with systemic machineries to bring down the human immune system as well as proliferate dramatically in a short period which in turn cause a pronounced ailment to the human health. In vitro evaluation of four purified compounds isolated from rhizosphere bacterium Exiguobacterium mexicanum tested against clinical pathogens mentioned above by disc diffusion method showed the two compounds viz., 3,6,18-trione, 9,10-dihydro-12′-hydroxyl-2methyl-5-(phenyl methyl) (5′-alpha, 10-alpha)-dihydroergotamine (C3) and dipropyl – S-propyl ester (C4) exhibit antibacterial property against all the tested pathogens. Among the four clinical pathogens tested, compound C3 has shown higher zone of inhibition against S. enterica with 17 ± 0 mm, followed by S. flexneri with 16.5 ± 0.7 mm, E. coli with 15 ± 0 mm and K. pneumoniae with 14 ± 0 mm, respectively. The compound C4 has shown higher antimicrobial activity against S. enterica with 21.5 ± 0.7 mm zone of inhibition, followed by S. flexneri with 19.5 ± 0.7 mm, E. coli with 17 ± 0 mm and K. pneumoniae with 16 ± 0 mm, these two compounds were found to be safer when subjected to rat haematological and enzymatic analysis.

Graphical abstract

Keywords: Pathogen; Antibacterial compound; Spectral analysis; Bioassay; Toxicology.