Microbial metabolism in petroleum

Perry, J. T., 1984, Microbial Metabolism of Cyclic Alkanes In Petroleum Microbiology (edited by R. M. Atlas), MacMillan Publishing Co., New York, pp. 61-98. 

Singer, M.E. and Finnerty, W.R. Microbial metabolism of straight-chain and branched alkanes, in Petroleum Microbiology, Atlas, R.M., Ed. (New York Macmillan, 1984), pp. 1-59. 

In the selection of a microbial system and bioremediation method, some examination of the degradation pathway is necessary. At a minimum, the final degradation products must be tested for toxicity and other regulatory demands for closure. Recent advances in the study of microbial metabolism of xenobiotics have identified potentially toxic intermediate products (Singleton, 1994). A regulatory agency sets treatment objectives for site remediation, and process analysis must determine whether bioremediation can meet these site objectives. Specific treatment objectives for some individual compounds have been established. In other cases total petroleum hydrocarbons total benzene, toluene, ethyl benzene, and xylene (BTEX) or total polynuclear aromatics objectives are set, while in yet others, a toxicology risk assessment must be performed. 

The microbial metabolism of a large number of hydrocarbons has been thoroughly studied and described in the literature. In contrast, much less is known about the metabolism of organosulfur compounds found in petroleum. These investigations have been hampered by the commercial unavailability of most of the sulfur compounds of interest. 

Some of the first studies on the biodegradation of sulfur compounds focused on their fate and removal from oil-contaminated environments. Another major area of study is the microbial process of "biodesulfurization" which has been suggested as a means of selectively removing sulfur compounds from petroleum prior to refining. Information gathered from these two areas of research provide the basis of the present knowledge of metabolism of organosulfur compounds in petroleum. This information is reviewed with emphasis on the metabolism of dibenzothiophenes and n-alkyl tetrahydrothiophenes (n-alkyl thiolanes). 

FEDORAK Microbial Metabolism of Organosidfur Compounds in Petroleum 95... 

This article reviews information gathered from these areas of research which provides the bulk of our present knowledge of metabolism of OSC in petroleum. The order of presentation is that of increasing experimental control over the microbial activities. First, observations of the persistence of OSC in petroleum-contaminated environments and their occurrence in petroleum reservoirs will be presented. In these situations, we exert little or no control over the microbial activities which occur. Next, results from laboratory studies with crude petroleum or petroleum fractions will be presented. Finally, laboratory work with pure OSC will be summarized. Using the latter controlled conditions, metabolic intermediates and pathways for a few OSC have been elucidated. 

FEDORAK Microbial Metabolism of Organosulfur Compounds in Petroleum 97... 

FEDORAK Microbial Metabolism of Organostdfur Compounds in Petroleum 103... 

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As is evident from the focus of this symposium, there is a great interest in sulfur compounds in petroleum. In addition, there is no doubt that microbial metabolism has played a major role in the quantity and quality of the World s petroleum. Yet there is relatively little information on the microbial metabolism of OSC found in petroleum. This paper provided a thorough review of the literature on the topic but it discussed only 20 pure OSC. I am not aware of work which has been done with any other compounds. In their studies of several crude oils, Rail et al. (13) isolated and identified 176 organic sulfur compounds which were grouped into 13 classes. Many more sulfur compounds have been identified since their work. Thus there is much more to be learned about microbial transformations of these compounds. 

The topic of microbid metabolism of OSC in petroleum has been of interest for over three decades. In fact, U.S. patents were issued in the early 1950 s for methods of biodesulfurization (74. 75). Although there has been progress in understanding the microbial metabolism of OSC, this area of research is still in its infancy. With the appropriate collaboration between organic chemists and microbiologists, there are many new facts to uncover. 

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