APPLICATION OF RESOURCE-RATIO THEORY TO HYDROCARBON BIODEGRADATION

Resource-ratio theory is one of the major logical frameworks used in e cology to predict how competition for growth-limiting resources influe nces biological diversity and function within a biological community. This paper presents experimental and other evidence that resource-rati o theory can also be applied to nutrient supplementation in hydrocarbo n biodegradation. The theory makes two major predictions about nutrien t supply and hydrocarbon biodegradation: (i) that changes in nitrogen (N) and phosphorus (P) supply ratio conditions will significantly alte r biodegradation rates and that these changes in N:P ratio will cause significant shifts in microbial community composition and (ii) that ch anges in absolute nutrient supply levels, at constant supply ratios, w ill alter total hydrocarbon-degrader biomass, resulting in altered rat es of hydrocarbon biodegradation. Here we analyze data from previous e xperiments studying the effects of N and P supply conditions on hexade cane and phenanthrene degradation in soil slurry reactors. Through the development of resource supply maps relating degradation rate and IU and P supply conditions, it is shown that hydrocarbon degradation in s lurry reactors is consistent with both major predictions of the theory . Further supporting evidence from previous studies on crude oil degra dation in Arctic soils, hydrocarbon degradation in marine oil spills, and hydrocarbon composting in soils is also discussed in the context o f resource-ratio theory. The pa per suggests th at more specific exper imental studies are needed to verify further the utility of theory and that, once more extensive data are available, the theory should provi de a strong theoretical foundation for optimizing nutrient formulation and application strategies for hydrocarbon degradation in the future.