Characterization of Antibiotics Inhibitory to Methicillin Resistant Staphylococcus aureus (MRSA) from Soil Actinomycetes

Abstract

Actinomycetes are subgroup of actinobacteria which include Streptomyces, a source of many important antibiotics. Methicillin-resistant Staphylococcus aureus is one of the emerging infectious diseases which pose a significant health and occupational risk worldwide. The aim of this work was designed to isolate and characterize antibiotic producing actinomycetes from soil capable of inhibiting methicillin-resistant Staphylococcus aureus. Soil samples collected from rhizosphere of plants, agricultural soil and hospital dump soil cultured on starch casein agar yielded only one (1) isolate showing antibacterial activity against a diameter of zone of inhibition for Methicillin-resistant Staphylococcus aureus (12 mm), Bacillus subtilis (16 mm), Escherichia coli (15 mm) and Pseudomonas aeruginosa (14 mm). Ethyl acetate was used to extract antibacterial compounds from the culture filtrate. Thin Layer Chromatography was done on silica gel using Methanol: Chloroform (9.4:0.6). The extract was analyzed with Fourier Transform-Infrared Red spectroscopy with a view to establish the chemical identity of the compound.  The isolate showed good growth and white aerial mycelium on starch-casein agar and whitish-brown substrate mycelium on starch-casein broth. The isolate also utilized glucose, sucrose and fructose during sugar fermentation and were positive on amylolytic activity, hydrogen sulfide production, and nitrate reduction, milk Coagulation and Peptonization and gram staining. Results also suggest that the actinomycete isolate belongs to the genus Micromonospora. A candidate (Rf: 0.8) with antibiotic potential against methicillin-resistant Staphylococcus aureus was isolated from soil habitat. The chemical finger prints identified in the extract included aldehydes, alkynes, 2 aromatic rings, alkanes and alkynes. The extract (Rf: 0.8) has antibiotic potential against methicillin-resistant Staphylococcus aureus. The chemical finger prints identified in the extract included aldehydes, alkynes, 2 aromatic rings, alkanes and alkynes. Based on biochemical and morphological characterization, the isolate (A2) belongs to the genus Micromonospora of the family Micromonosporoceae.