Microbiological Degradation of Organic Components in Oil Shale Retort Water: Organic Acids

Abstract

The losses of benzoic acid and a homologous series of both mono- and dibasic aliphatic acids in oil shale retort water were monitored with time (21 days) in liquid culture (4% retort water, vol/vol) inoculated with soil. The organic acids constituted approximately 12% of the dissolved organic carbon in retort water, which served as the sole source of carbon and energy in these studies. The levels of the acids in solution were reduced by 80 to 90% within 9 days of incubation. From mass balance calculations, the decrease in dissolved organic carbon with time of incubation was equal to the formation of CO 2 and bacterial cell carbon. The decrease in the level of the acid components, either from degradation to CO 2 or incorporation into bacteria, would account for ∼70% of the loss in dissolved organic carbon within the first 9 days of incubation and would account for ∼50% of the loss over the entire 21-day incubation period.

State of research: environmental pathways and food chain transfer.

“…The focus on delineating soil processes that control biological availability ofnonnutrient compounds like certain radioelements is relatively recent (23)(24)(25). Data on microbial degradation of organic compounds are plentiful but have not yet been brought to a sharp focus as regards controlling variables (16,18,26,27).…”

“…Since many of the micro-organisms are ubiquitous, their presence can be expected in soil systems as well as sediment systems. The relative numbers of specific organisms in a soil sample may also depend on substrate composition and time allowed for them to grow in (26,27,109). Simpler aromatic compounds like benzoic acid evidently can be metabolized as a sole carbon source, but it is thought that the more complex compounds will require concerted action of several bacteria that partially degrade the parent compound by a variety of metabolic pathways (17,27,110).…”

Behavior of complex mixtures in aquatic environments: a synthesis of PNL ecological research

“…This is recognized as an important environmental process, but in actual situations, its magnitude and direction are difficult to predict (Atlas, 1981;Cerniglia, 1981;Landrum and Scavia, 1983}. Even in the presence of allochthonous sources of carbon, for example, microbial degradation is only partial (Horvath, 1972;Rogers et al, 1981), and concurrent biosynthesis of more complex compounds can also occur (Atlas, 1981}. These same considerations may apply to organisms at higher trophic levels as well (Vaughan, 1984).…”

“…Among microbial organisms studied in vitro, some species only partially degrade specific compounds or degrade only certain compounds. Mixed microbial populations under artificial conditions can completely metabolize a pure PAH to C0 2 , but this evidently does not happen under ordinary conditions of plentiful carbon sources (Rogers et al, 1981;Horvath, 1972;Jordan and Payne, 1980). In field studies of petroleum spills, sulfur heterocyclic analogs of PAH and their alkylated metabolites persisted disproportionately to other oil compound classes, and these differences were not explainable on the basis of bioconcentration (Grahl-Nielsen et al, 1978;Dillon et al, 1978;Warner, 1975).…”