title: Surface active properties of bacterial strains isolated from petroleum hydrocarbon-bioremediated soil.
abstract: Two bacterial strains identified as Ralstonia picketti (BP 20) and Alcaligenes piechaudii (CZOR L-1B) were isolated from petroleum hydrocarbon-contaminated soil following bioremediation treatment. The surface active properties, e.g. surface tension, emulsification and foamability of their culture filtrates were evaluated. Bacterial cell-surface hydrophobicity (BAH) as measured by analyzing cell affinity towards aliphatic and aromatic compounds was also determinated. The bacteria grew in liquid cultures containing 1% (v/v) of crude oil as carbon and energy source at 30 degrees C under aerobic conditions. The surface tensions were reduced to 61 mN/m and 55 mN/m by Ralstonia picketti and Alcaligenes piechaudii, respectively. The emulsification index (EI24) was almost 100% for all tested compounds except diesel oil. The stability of the emulsions was deteminated at 4 degrees C, 45 degrees C and 65 degrees C. The emulsions were stable at 4 degrees C. Ralstonia picketti was better foam inducer (FV = 50 ml) compared to Alcaligenes piechaudii (FV = 10 ml). The BAH measurements revealed higher adhesion of Alcaligenes piechaudii cells towards different hydrocarbons compared to Ralstonia picketti cells. The strains were found to have a surface hydrophobicity in the following order: aliphatic hydrocarbons, BTEX, and PAHs. The ability to adhere to bulk hydrocarbon is mostly a characteristic of hydrocarbon-degrading bacteria. The strains were found to be better emulsifiers than surface tension reducers. They produce water-soluble extracellular bioemulsifiers. Both bacterial isolates have good properties to use them, mainly in the petroleum industry, e.g. in enhanced oil recovery and in bioremediation processes-primarily due to their emulsification property, i.e. emulsion forming and stabilizing capacity.
authors.affiliation: Institute for Ecology of Industrial Areas, 40-844 Katowice, Poland. pla@ietu.katowice.pl
authors.forename: Grazyna A
authors.initials: GA
authors.lastname: Płaza
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Ulfig
authors.forename: Robin L
authors.initials: RL
authors.lastname: Brigmon
mesh_terms: D000421:Alcaligenes / Q000302:isolation & purification* / Q000378:metabolism / Q000502:physiology; D001673:Biodegradation, Environmental; D002462:Cell Membrane; D006838:Hydrocarbons / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D010578:Petroleum / Q000378:metabolism*; D043367:Ralstonia / Q000302:isolation & purification* / Q000378:metabolism / Q000502:physiology; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism; D013499:Surface Properties; D013501:Surface-Active Agents / Q000378:metabolism*; D013997:Time Factors
chemical_list: D006838:Hydrocarbons; D010578:Petroleum; D012989:Soil Pollutants; D013501:Surface-Active Agents