title: Sequential growth of bacteria on crude oil.
abstract: By modification of the enrichment culture procedure three bacterial strains capable of degrading crude oil in sea water were isolated in pure culture, UP-2, UP-3, and UP-4. Strain UP-2 appears to be highly specialized for growth on crude oil in sea water since it showed strong preference for oil or oil degradation products as substrates for growth, converted 66% of the oil into a form no longer extractable by organic solvents, quantitatively degraded the paraffinic fraction (gas chromatographic analysis), emulsified the oil during exponential growth, and produced 1.6 x 10-8 cells per mg of oil. After exhaustive growth of UP-2 on crude oil the residual oil supported the growth of UP-3 and UP-4, but not a previously isolated oil-degrading bacterium, RAG-1. Strains UP-2, UP-3, and UP-4 grew on RAG-1-degraded oil (specifically depleted of n-alkanes). The growth of UP-3 and UP-4 on UP-2 and RAG-1-degraded oil resulted in the production of new paraffinic compounds as revealed by gas chromatography. When the four strains were grown either together in a mixed culture or sequentially, there was over 75% oil conversion. By plating on selective media, growth of the individual strains was measured kinetically in the reconstituted mixed culture, revealing competition for common growth substances (UP-2 and RAG-1), emhanced die-off (UP-2), and stabilization (UP-4) during the stationary phase.
mesh_terms: D000473:Alkanes / Q000378:metabolism; D001173:Arthrobacter / Q000254:growth & development / Q000378:metabolism; D001419:Bacteria / Q000254:growth & development* / Q000378:metabolism; D001673:Biodegradation, Environmental; D002849:Chromatography, Gas; D003470:Culture Media; D005648:Fuel Oils; D006838:Hydrocarbons / Q000378:metabolism; D007700:Kinetics; D008858:Microscopy, Phase-Contrast; D010578:Petroleum; D012623:Seawater
chemical_list: D000473:Alkanes; D003470:Culture Media; D005648:Fuel Oils; D006838:Hydrocarbons; D010578:Petroleum