Improving Accuracy and Availability of Productivity Methods for a Keystone Functional Group of Microbes

University Of Georgia Research Foundation Inc, Athens GA

Investigators

Abstract

ABSTRACT Proposal: Improving Accuracy and Availability of Productivity Methods for a Keystone Functional Group of Microbes Salt marsh plants exceedingly productive, as also are the ascomycetes (fungi) that are secondary microbial producers utilizing marsh plant organic matter as an energy source. The combination of marsh grass-marsh fungal high production is likely to be one of the basic factors underlying the high output of marine animals from salt marsh ecosystems. Because fungi in the standing-decaying marsh grass systems grow almost exclusively within the opaque solid dead plant mass, monitoring their productivity and biomass accumulation are technically difficult. This problem has been surmounted by development of biochemical analytical methods that make use of fungal-proxy molecules. The best of these has proven to be ergosterol, a cell-membrane component nearly unique to fungal cells. Ergosterol is an indicator molecule for living fungal mass and is Ergosterol relatively easily extracted from naturally decaying materials and measured by HPLC (high-performance liquid chromatography). Rates of fungal synthesis (= fungal productivity) can be measured as rates of incorporation of C14 into ergosterol, where the rate of increase in radioactivity in ergosterol parallels the rate at which the fungus is growing. It is herein proposed to seek two basic improvements to the fungal-productivity method. The acetate-to-ergosterol method has only recently become available and there remains much to be done regarding refinement of the method. One very basic item that needs attention is the conversion factor for calculating the rate of fungal organic-mass production from the rate of acetate incorporation into ergosterol. There are values available for this factor, but they range widely, and no one of the five or six investigators currently working in the field of fungal productivity has concentrated experimental efforts on this specific problem. It is proposed herein to do so, testing a range of environmental conditions and a range of target fungal species. Such a method, using the well-known dansyl fluorophore, has appeared in the drug-testing literature that is directly analogous to the acetate-to-ergosterol method. It is proposed herein to test whether this method can be used to measure fungal productivity in naturally decaying marsh grass leaves. If it can be so used, the ability to measure fungal productivity in ecosystems would become available in a wider range of laboratories (as opposed to its current restriction to those licensed for handling of radioisotopes). Broader Impacts: The research proposed would improve the utility of the methods now available for monitoring fungal production. This would provide better tools for investigators working at the edges of coastal oceans, marine sites that are currently in urgent need of attention due to their susceptibility to anthropogenic damage. More importantly, the new methodological information would also be of considerable value to forestry scientists, aquatic-ecosystem scientists, agricultural scientists, and industrial-fermentation scientists, because of the great importance of fungal activities in these fields.