Characterisation of a novel naturally-modified biogenic calcium carbide-containing exopolysaccharide produced from Pseudomonas aeruginosa strain S16 from soil in Nigeria, West Africa

Antibiotic resistance, that occurs globally, has led to a reduction in the efficacy of many contemporary conventional antibiotics. The aim of this study was to characterise an exopolysaccharide, produced from Pseudomonas aeruginosa strain S16, accession number OQ734845, that was observed to be effective against an identified strain of Klebsiella pneumoniae , at 0.156 g/L, and against Staphylococcus aureus SO183, at 0.156 g/L and 0.260 g/L. Pseudomonas aeruginosa strain S16, was previously isolated from soil, in a mixed animal farm, at Ajibode area, Oyo state, Ibadan, Nigeria, through the pour plate method, before it was identified, through biochemical tests, and molecular studies. HPLC and MS of the exopolysaccharide, revealed glucose, rhamnose, xylose arabinose, D-ribose, galactose, mannose and inositol, and each possessed varying peaks. The phenol-sulfuric acid method, quantified the carbohydrate sugars concentration, as 0.0060 g/L. SEM revealed a sparsely flaky, exopolysaccharide surface, with globular projections. EDX revealed, nitrogen (48.00%); carbon (20.10%); phosphorus (12.6%); sodium (8.00%); oxygen (6.00%); calcium (2.30%); chlorine (1.20%); magnesium (0.89%); zinc (0.67%); potassium (0.44%), and manganese (0.33%). FTIR spectroscopy, revealed magnesium oxide, zinc oxide, calcium carbide compounds and their internal bonds; oxygen-manganese-oxygen bonding, and carboxyl, imine/oxime, amide/peptide, nitro, halo, and anhydride functional groups. The exopolysaccharide was a heteropolysaccharidic, novel, naturally-modified, biogenic calcium carbide-containing, exopolysaccharide The variety of chemicals more than likely, added to the exopolysaccharide, the potential for a range of biological activities. From available documented research, this is the first report of an exopolysaccharide naturally modified by biogenic calcium carbide, and sodium, magnesium, potassium, and manganese ions.