Showing papers on "Microbial biodegradation published in 1975"

Effects of temperature and crude oil composition on petroleum biodegradation.

Abstract: The biodegradability of seven different crude oils was found to be highly dependent on their composition and on incubation temperature. At 20 C lighter oils had greater abiotic losses and were more susceptible to biodegradation than heavier oils. These light crude oils, however, possessed toxic volatile components which evaporated only slowly and inhibited microbial degradation of these oils at 10 C. No volatile toxic fraction was associated with the heavier oils tested. Rates of oil mineralization for the heavier oils were significantly lower at 20 C than for the lighter ones. Similar relative degradation rates were found with a mixed microbial community, using CO2 evolution as the measure, and with a Pseudomonas isolate from the Arctic, using O2 consumption as the measure. The paraffinic, aromatic, and asphaltic fractions were subject to biodegradation. Some preference was shown for paraffin degradation, especially at low temperatures. Branched paraffins, such as pristane, were degraded at both 10 and 20 C. At best, a 20% residue still remained after 42 days of incubation. Oil residues generally had a lower relative percentage of paraffins and higher percentage of asphaltics than fresh or weathered oil.

Chlorinated C1 and C2 hydrocarbons in the marine environment.

Abstract: A range of chlorinated hydrocarbons derived from C$_{1}$ and C$_{2}$ hydrocarbons is manufactured industrially They are used as intermediates for further chemical manufacture and also outside the chemical industry as solvents or carriers In the latter category losses in use are eventually dispersed to the environment The distribution of some of these compounds, including chloroform, carbon tetrachloride, trichloroethylene, perchloroethylene and trichloroethane, in the environment (air, water and marine sediments) has been investigated and the results are presented The concentrations found have been compared with acute toxicity levels to fish and other aquatic organisms, ascertained by laboratory bioassay The occurrence of the compounds has been determined in a number of marine organisms, especially those at higher trophic levels, and the accumulation of some of them has been investigated in the laboratory Chemical and microbial degradation processes have been studied in the laboratory to help determine the course of their removal from the aqueous and aerial environment, and the half lives of some of the compounds have been estimated It is concluded that these compounds are not persistent in the environment, and that there is no significant bioaccumulation in marine food chains

Microbial degradation of ethylenediaminetetraacetate in soils and sediments.

Abstract: [14C]ethylenediaminetetraacetate (EDTA) was shown to be slowly biodegraded to 14CO2 in soils and sediments under aerobic conditions and by microorganisms in mixed liquid culture. EDTA chelates of Cu, Cd, Zn, Mn, Ca, and Fe added to soil were equally degraded, while Ni-EDTA was degraded more slowly.

Microbial degradation of ethylenediaminetetraacetate in soils and sediments

Abstract: [14C]ethylenediaminetetraacetate (EDTA) was shown to be slowly biodegraded to 14CO2 in soils and sediments under aerobic conditions and by microorganisms in mixed liquid culture. EDTA chelates of Cu, Cd, Zn, Mn, Ca, and Fe added to soil were equally degraded, while Ni-EDTA was degraded more slowly.

Biodegradation of oil on water surfaces

Abstract: Free-floating oil slicks on bodies of sea and fresh water are disposed of microbial degradation at a greatly enhanced rate by applying the essential microbial nutrients, nitrogen and phosphorus, to the oil slick in a form that dissolves in or adheres to the oil and thus selectively stimulates the activity of oil-metabolizing microorganisms.

Microbial ecology and the problem of petroleum degradation in chespeake bay

Abstract: Petroleum degradation in the marine environment is one of the many processes effected by microorganisms. Control of this process will be achieved only through an understanding of microbial ecology. Information obtained on the ecology of mercury-metabolizing bacteria in Chesapeake Bay has provided interesting comparisons with the petroleum-degrading microbial populations. Petroleum degradation studies are being done to obtain a seasonal incidence, as well as species distribution of petroleum-degrading microorganisms in Chesapeake Bay. From analysis of water and sediments collected at two stations in Chesapeake Bay it was found that the concentration of petroleum in an oil polluted site in Baltimore Harbor was five times greater than in Eastern Bay. The numbers of petroleum-degrading microorganisms, measured by direct and replica plating, in the water and sediment samples were related to the concentration of soil 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 water and sediment samples collected in Baltimore Harbor grew on substrates representative of the aliphatic, aromatic and refractory hydrocarbons. From analyses of species distribution, it was observed that a 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 objective of work in process is to determine whether a seasonal fluctuation in the petroleum-degrading microflora occurs in the Bay.