Microbial Ecology of Petroleum Utilization in Chesapeake Bay

Analysis of water and sediments collected at two stations in Chesapeake Bay demonstrated four to five times the concentration of petroleum in an oil polluted site in Baltimore Harbor compared with the station in Eastern Bay which served as a control. The numbers of petroleum-degrading microorganisms, measured by direct and replica plating, in the water and sediment samples were related to the concentration of oil in each sample. Total yields of petroleum-degrading microorganisms grown on an oil substrate were greater for those organisms exposed to oil in the natural environment. Microorganisms isolated from an oil-contaminated environment produced cell yields under “natural” conditions, i.e., laboratory simulation of growth conditions in the natural environment, which equaled the yields of microorganisms which had not been previously exposed to oil and were grown under optimum conditions. Microorganisms isolated from water and sediment samples collected in Baltimore Harbor grew on substrates representative of the aliphatic, aromatic and refractory hydrocarbons. The hydrocarbon-utilizing fungus, Cladosporium resinae and actinomycetes were predominant among the hydrocarbon-utilizing isolates. Microbial degradation of petroleum in Chesapeake Bay appears to be mediated by the autochthonous microbial flora, the seasonal incidence of which is presently under study.