N-128. Microbial Succession on Native Rock and Artificial Surfaces in the Marine Environment

A. Patel, J. Steele, J. Fuhrman;
Univ. of Southern California, Los Angeles, CA.

Microbial biofilms are ubiquitous in the marine environment, ranging from the thin veneer encasing single minute sediment particles to the thick encrusting layers seen on submerged pylons. The marine biofilm environment therefore encompasses a very significant part of the microbial biomass in the oceans. The microbial composition of a biofilm at a given time is also known to strongly influence subsequent settlement patterns. We performed an in depth analysis of early microbial succession of attached marine communities. By using shaped native rocks to investigate waves of microbial colonization from early (days) to late time points (months), we employed a strategy aimed at displaying natural marine biofilm development as analyzed by molecular genetic techniques. In parallel to the assessment of biofilm community shifts, we obtained data for microbial composition within the immediate sediment and water column environmental compartments. This simultaneous approach allowed us to track community variation between the biofilm, sediment, and water column to reveal the taxa unique and common to each medium. For comparison, we also used a more commonly studied artificial surface, PVC. The microbial DNA fingerprinting technique Automated Ribosomal Intergenic Spacer Analysis (ARISA) was used to obtain information on bacterial community composition. A dendritic cluster analysis of the data, incorporating a high degree of sample replication, revealed clear differences between the environmental compartments. The biofilm communities at the various time points were clearly unique, and species richness also varied temporally. Later time points appeared to be more diverse and had higher degrees of evenness. Water column communities were most distinct, branching the deepest. Biofilms developing adjacent to the sediment showed similarities to the sediment consortia, whereas biofilms grown 10m above the sea floor were very much unlike their surrounding medium, the water column. A PVC versus rock surface comparison revealed that the substratum can have a marked influence on shaping the bacterial consortia and should always be considered in future investigations.

142/N. Extreme Environments - I

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