Antimicrobial Activity of Purified Emulsifier of Acinetobacter Genospecies Isolated from Rhizosphere of Wheat

Among thirty seven wheat rhizosphere isolates, only Acinetobacter genospecies 3, A15 emulsified all thirty oil substrates and combinations in LB medium. It emulsified diesel oil wide range of temperatures 0°C-40°C, pH 1.5–12, 5–25% salinity with EI_30Days of 75.9% at 0°C. Emulsification activity was comparable to SDS, Tween 20 and 80, Triton X100 surfactants and was not affected by chelators and enzymes. Partially purified bioemulsifier was composed of 50% polysaccharide, 30% protein and 2% lipid. It was not surface active but showed activity against human pathogens, Staphylococcus aureus, Salmonella typhimurium, Klebsiella pneumoniae, Aspergillus niger, Aspergillus fumigatus, Candida humicola, Candida albicans, Cryptococcus and inhibited PS and Wish viral cell lines. Purified compound at R.T.1.440 with diesel emulsification activity was obtained by HPLC. Infrared spectrum confirmed OH, N-H or COOH; C=O; C=C or Ar or C-H; NO₂ or Ar-O; Ar-C-O; CO functional groups. GC-MS and ¹HNMR analysis respectively indicated methyl esters and methylated fatty acids as structural components of bioemulsifier. Microbicidal activity of purified bioemulsifier against C. albicans was observed microscopically.