Single cell activity of aerobic anoxygenic phototrophic bacteria in the Delaware Estuary
Date
2013
Authors
Journal Title
Journal ISSN
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Publisher
University of Delaware
Abstract
Aerobic anoxygenic phototrophic (AAP) bacteria are abundant in
estuaries, coastal regions and in the open ocean, comprising 1-30% of total
prokaryotes. To understand their distribution and potential contribution to the
carbon cycle, single cell activity of the microbial community was determined by
3H-leucine incorporation detected using microautoradiography combined with
additional steps to identify AAP bacterial cells before and after
microautoradiography. The approach was used on transects through the
Delaware estuary in August and November 2011. The percent of active AAP
bacteria was up to two fold higher than the percentage of active bacteria for
the rest of the bacterial community in the estuary. Likewise, the silver grain
area associated with active AAP bacteria was larger than that for the rest of
the community, indicating higher rates of leucine consumption by AAP
bacteria. The difference between the activity of AAP bacteria and other
bacteria was greatest in high salinity waters and was lowest in freshwater.
The incorporation of 3H-leucine by AAP bacteria did not vary with light under
ambient light conditions as well as in incubations with constant light and
darkness. Our results suggest that AAP bacteria are more active than other
bacteria in many parts of the estuary, just not in all locations.