THE MOBILE BIOFILM UNIT (MBU): A TECHNOLOGICAL INNOVATION IN GEOMICROBIAL STUDIES

Microbial biofilms influence high-temperature siliceous sinter biofabrics by colonizing accretionary surfaces as sinter accumulates. The various stages of hyperthermophilic biofilm formation have been documented by comparing the distribution and character of non-mineralized and mineralized bacteria on and inside natural sinters and on glass slides deployed in near-boiling hot springs. While this iterative approach has revealed a number of key aspects of biofilm formation in hot spring ecosystems, a complete understanding of the ways in which hyperthermophiles impact biofabric formation requires an instrument capable of monitoring microbial colonization and behavior in such systems on spatial and temporal scales relevant to biofilm processes.

We have designed, constructed, and tested a Mobile Biofilm Unit (MBU) for characterizing biofilms microscopically and spectroscopically in their natural setting. An integral component of the MBU is a portable flow cell system coupled to a microscope, a digital camera, and a prototype microscope-coupled imaging spectrometer. This configuration allows us to follow in real time the development of biofilms inoculated and fed from hydrothermal fluid channeled into the flow cells from a hot spring. A laboratory based unit with the same hardware configuration as the MBU provides a means to conduct parallel experiments with populations of dominant members of thermophilic and hyperthermophilic consortia. The laboratory based unit is also being used to conduct abiotic mineralizing experiments.

The comparison of indigenous microbial biofilm communities grown under hydrodynamically controlled conditions in fluids extracted from the natural environment and biofilms of cultured relatives of populations in the indigenous communities grown under similar hydrodynamic conditions improves significantly our ability to recognize the role of microbial biofilms in biofabric formation in mineralizing ecosystems. Some of the earliest microbial communities likely occurred as benthic biofilms in ancient hydrothermal ecosystems. We report the results of our first set of field experiments carried out using the MBU in a hot spring ecosystem.