The importance of soil characteristics to the structure of alkane-degrading bacterial communities on sub-Antarctic Macquarie Island

An investigation of the influence of soil properties on microbial community dynamics in soil on sub-Antarctic Macquarie Island found that both carbon and nitrogen were important factors in determining soil microbial community structure. The phylogenetic diversity of soil microbial communities in hydrocarbon contaminated and non-contaminated sites was compared to the diversity of hydrocarbon-degrading genes and soil physicochemical characteristics. Genes involved in hydrocarbon degradation including alkane mono-oxygenase, catchecol-2,3-dioxygenase and naphthalene dioxygenase were found throughout the study sites. Terminal restriction fragment length polymorphism analysis of the 16S rRNA and alkB genes found that the patterns of diversity of these two genes were only correlated with each other where measurable levels of hydrocarbons were detected. We found that different sections of the microbial community are affected by different environmental factors depending on whether hydrocarbons were present. The overall microbial community structure as measured by the 16S rRNA gene was most influenced by the presence of carbon both as total organic carbon and as petroleum hydrocarbons. The alkane-degrading community was also influenced by carbon. Where hydrocarbons were present petroleum hydrocarbon concentration as well as the form and concentration of nitrogen present also influenced the alkane-degrading community. This level of complexity in the microbial community dynamics suggests that it is unlikely that one single environmental factor is responsible for structuring microbial communities.