MICROBES 



Hydrocarbon-degrading microbes have been isolated from various types 

 of marine sediments. After introduction of oil into sediments, there is a 

 large increase in the hydrocarbon-degrading microbial population (Zobell and 

 Prokop 1966, Walker et al . 1975). Hughes and McKenzie (1975) added oil to 

 sediment and followed oil degradation by taking sediment cores for 2 years. 

 The surface layer of oil was degraded, but oil below the surface remained 

 unchanged, indicating that microbial degradation takes place at the water- 

 sediment interface. Only slow hydrocarbon oxidation occurred in anaerobic 

 muds, and it was speculated that the sulfate-reducing bacterium Desulfovibrio 

 was responsible for the degradation that was observed. 



The alkanes are rapidly degraded by sediment microbes, followed by slower 

 attack on isoalkanes, cycloalkanes, and aromatic hydrocarbons (Zobell 1969; 

 Blumer 1973). In oil spill areas, mixed cultures of hydrocarbon-degrading 

 microbes are able to metabolize both aliphatic and aromatic hydrocarbons 

 (Walker et al. 1975). Different crude and refined oils would be expected 

 to show different rates of degradation because of variations in the relative 

 amounts of different petroleum components. In one experiment, hydrocarbon 

 microbes were allowed to act on two crude oils (South Louisiana and Kuwait) 

 and two refined oils (bunker C and No. 2 fuel oil). The South Louisiana crude 

 oil was most susceptible to microbial degradation, and the bunker C oil was 

 the least degraded in the 28-day study (Walker et al. 1976). The high con- 

 centration of high molecular weight polycyclic aromatic hydrocarbons in bunker 

 C oil may explain its resistance to degradation. Through the use of radiolabeled 

 hydrocarbon, it has been found that sediment collected off the coast of Georgia 

 rapidly degraded three-ringed aromatics, but only slowly attacked four- and 

 five-ringed compounds. 



in addition to bacteria, hydrocarbon-degrading yeast and filamentous 

 fungi have been isolated from marsh sediments along the coasts of Louisiana 

 and North Carolina (Meyers and Ahearn 1972, Perry and Cerniglia 1973). A 

 we H -characterized species is the filamentous fungus Cladosporium resinae, 

 which occurs in estuarine sediments, and can use alkanes as the sole carbon 

 sourc (Walker and Conney 1973). 



MHOFAUNA AND MACROFAUNA 



In addition to microbes, marine sediments also contain a large inter- 

 stitial community called the meiofauna, which is composed of harpactoicoid 

 copepods, nematodes, turbellarians, and small polychaetes. Many species from 

 these groups are deposit feeders, which are thus directly exposed to hydro- 

 carbons in the sediments. Polychaete worms, particularly Capitella aapitata, 

 are associated with areas of high oil input (Reish 1971, Sanders et al . 1972). 

 Detritus associated with sediment is used for nourishment by many benthic 

 polychaetes. Much of this detritus is formed in the water where hydrocarbons 

 can absorb to it. Cell -free extracts of Capitella capitata have hydrocarbon- 

 metabolizing enzymes, and living animals will take up polycyclic aromatic 

 hydrocarbons from the sediment with subsequent metabolism to various hydrox- 

 ylated derivatives (Lee et al. 1977b). 



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