Microbial community patterns of potential substrate utilization: a comparison of salt marsh, sand dune, and seawater-irrigated agronomic systems

Microbial community patterns of potential substrate utilization were examined at eight study sites. Sample microbial communities were from different habitats including constructed and natural salt marshes, a seawater-irrigated agronomic system, and, for a non-saline comparison, a coastal sand dune. Microbial communities were characterized by patterns of sole carbon source (substrate) utilization using Biolog microplates. Sampling sites were characterized based on analysis of soil biotic and physical properties. Relationships among the eight microbial communities based on substrate utilization potential, and among the sampling sites based on biotic and physical characteristics, were similar. Microbial communities from natural salt marshes at two geographically distant locations had similar patterns of potential substrate utilization. The constructed salt marsh community was dissimilar from the other communities (including two from natural salt marshes located in the same salt marsh complex) in potential substrate utilization. Seawater-irrigated agronomic sites were distinct from the other saline soil sites, possibly due to disturbance caused by agronomic practices. Potential substrate utilization of the microbial communities at the agronomic sites was intermediate compared to the other sites, e.g. higher than the constructed marsh but lower than the natural salt marshes. Relationships among the study communities determined by microbial potential substrate utilization and analysis of site characteristics primarily reflected similarity in habitat type, while geographical influences were less important.