Abundance and activity of Chloroflexi‐type SAR202 bacterioplankton in the meso‐ and bathypelagic waters of the (sub)tropical Atlantic
Summary The contribution of Chloroflexi ‐type SAR202 cells to total picoplankton and bacterial abundance and uptake of d ‐ and l ‐aspartic acids (Asp) was determined in the different meso‐ and bathypelagic water masses of the (sub)tropical Atlantic (from 35°N to 5°S). Fluorescence in situ hybridizat...
Published in: | Environmental Microbiology |
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Main Authors: | , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Wiley
2008
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Subjects: | |
Online Access: | http://dx.doi.org/10.1111/j.1462-2920.2008.01627.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1462-2920.2008.01627.x http://onlinelibrary.wiley.com/wol1/doi/10.1111/j.1462-2920.2008.01627.x/fullpdf |
Summary: | Summary The contribution of Chloroflexi ‐type SAR202 cells to total picoplankton and bacterial abundance and uptake of d ‐ and l ‐aspartic acids (Asp) was determined in the different meso‐ and bathypelagic water masses of the (sub)tropical Atlantic (from 35°N to 5°S). Fluorescence in situ hybridization (FISH) revealed that the overall abundance of SAR202 was ≤ 1 × 10 3 cells ml −1 in subsurface waters (100 m layer), increasing in the mesopelagic zone to 3 × 10 3 cells ml −1 and remaining fairly constant down to 4000 m depth. Overall, the percentage of total picoplankton identified as SAR202 increased from < 1% in subsurface waters to 10–20% in the bathypelagic waters. On average, members of the SAR202 cluster accounted for about 30% of the Bacteria in the bathypelagic waters, whereas in the mesopelagic and subsurface waters, SAR202 cells contributed < 5% to total bacterial abundance. The ratio of d ‐Asp : l ‐Asp uptake by the bulk picoplankton community increased from the subsurface layer ( d ‐Asp : l ‐Asp uptake ratio ≈ 0.03) to the deeper layers reaching a ratio of ∼1 at 4000 m depth. Combining FISH with microautoradiography to determine the proportion of SAR202 cells taking up d ‐Asp versus l ‐Asp, we found that ≈ 30% of the SAR202 cells were taking up l ‐Asp throughout the water column while d ‐Asp was essentially not taken up by SAR202. This d ‐Asp : l ‐Asp uptake pattern of SAR202 cells is in contrast to that of the bulk bacterial and crenarchaeal community in the bathypelagic ocean, both sustaining a higher fraction of d ‐Asp‐positive cells than l ‐Asp‐positive cells. Thus, although the Chloroflexi ‐type SAR202 constitutes a major bathypelagic bacterial cluster, it does not contribute to the large fraction of d ‐Asp utilizing prokaryotic community in the meso‐ and bathypelagic waters of the North Atlantic, but rather utilizes preferentially l ‐amino acids. |
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