Junge, K. University of Washington, kjunge@ocean.washington.edu
Staley, J. University of Washington/Dept. of Microbiology, jtstaley@u.washington.edu
Deming, J. University of Washington/School of Oceanography, jdeming@u.washington.edu

In sea-ice communities heterotrophic bacteria play a key role in carbon cycling, but little is known about the relationship between their abundance and genetic diversity. The bacterial enumeration anomaly, or the inability to grow and enumerate numerically important bacteria, has not been examined in sea ice. To address this, bacterial abundances were determined from melted sea ice samples using conventional and novel preparations for microscopic and viable counts. Denaturing gradient gel electrophoresis (DGGE) was used to assess the genetic diversity of numerically important sea-ice bacteria. Sea-ice bacteria were found to be very active metabolically (2-27% of direct counts by CTC stain). Numerically important organisms were successfully cultivated in natural sea water (1-60% of direct counts), indicating that the bacterial enumeration anomaly does not apply to this habitat. DGGE migration patterns revealed a low genetic diversity for predominant sea-ice bacteria. In marked contrast to other marine systems, only three major DGGE phylotypes comprised the numerically significant part of the sea-ice community. The methods used allowed the first-time assessment of the relationship between sea-ice bacterial abundance and genetic diversity. Phylogenetic studies in progress are examining the identiy of the cultured strains.
Day: Wednesday, Feb. 3
Time: 09:00 - 09:15am
Location: Hilton of Santa Fe
Code: CS60WE0900H