Microbial monitoring and environmental health assessments
Microorganisms respond rapidly to environmental disturbances and are useful indicators of ecosystem change. Early diagnosis and treatment of environmental problems, particularly in soils, via microbial community management can result in both environmental and economic benefits. Microorganisms are vital to developing a soil structure, increasing organic matter content and turnover, and increased nutrient cycling and are key to establishing a stable post-disturbance soil for the re-establishment of a self-sustaining vegetative cover. For example, the monitoring and management of soil microbes during soil removal, storage and replacement during mining can minimize microbial community changes to ensure that soil substrates are optimised for re-use in rehabilitation activities.
Significant functional redundancy amongst soil microbes means many of the major functions of the microbial biomass are unaffected by its exact species composition. This limits the value of using only taxonomic and molecular approaches to microbial monitoring. At MMS we monitor microbes using a combination of isolation and colony counting together with metabolic fingerprinting of the bacterial and fungal communities through their utilization of 95 different carbon sources using BIOLOG™ GN2 and SF-N2 microtitre plates.
Metrics derived from these measurements show the effects of soil nutrient conditions, disturbance, organic matter and water status on the microbiota. Multidimensional plots as shown here allow changes in microbial community status over time to be easily tracked and documented. Based on this information, and if bioremediation is required, treatments can then be explored to stimulate the existing microbiota or to restore essential missing components. For example, the filamentous networks of actinomycetes and fungi in soils are often severely disturbed through topsoil stripping and stockpiling activities.
A comparison of a native area, a revegetated area, and newly rehabilitating areas on a mine site over several years. Polar plots below show numbers and types of carbon sources used by bacterial (B) and fungal (F) communities of the native area and a newly rehabilitating area over the time period.