Reche I, Pace ML, Cole JJ
Institute of Ecosystem Studies, Box AB, Route 44A, Millbrook, NY 12545-0129, USA
Microb Ecol. 1998 Nov;36(3):270-280. doi: 10.1007/s002489900114.
Abstract Bacteria are key organisms in the processing of dissolved organic carbon (DOC) in aquatic ecosystems. Their growth depends on both organic substrates and inorganic nutrients. The importance of allochthonous DOC, usually highly colored, as bacterial substrate can be modified by photobleaching. In this study, we examined how colored DOC (CDOC) photobleaching, and phosphorus (P) and nitrogen (N) availability, affect bacterial growth. Five experiments were conducted, manipulating nutrients (P and N) and sunlight exposure. In almost every case, nutrient additions had a significant, positive effect on bacterial abundance, production, and growth efficiency. Sunlight exposure (CDOC photobleaching) had a significant, positive effect on bacterial abundance and growth efficiency. We also found a significant, positive interaction between these two factors. Thus, bacterial use of CDOC was accelerated under sunlight exposure and enhanced P and N concentrations. In addition, the accumulation of cells in sunlight treatments was dependent on nutrient availability. More photobleached substrate was converted into bacterial cells in P- and N-enriched treatments. These results suggest nutrient availability may affect the biologically-mediated fate (new biomass vs respiration) of CDOC.
摘要 细菌是水生生态系统中溶解有机碳（DOC）处理过程中的关键生物。它们的生长依赖于有机底物和无机养分。通常具有高色度的外源DOC作为细菌底物的重要性会因光漂白作用而改变。在本研究中，我们考察了有色DOC（CDOC）的光漂白以及磷（P）和氮（N）的可利用性如何影响细菌生长。我们进行了五个实验，对养分（P和N）以及阳光照射进行了控制。几乎在每种情况下，添加养分对细菌丰度、生产力和生长效率都有显著的正向影响。阳光照射（CDOC光漂白）对细菌丰度和生长效率有显著的正向影响。我们还发现这两个因素之间存在显著的正向相互作用。因此，在阳光照射以及P和N浓度增加的情况下，细菌对CDOC的利用加快。此外，阳光处理中细胞的积累取决于养分的可利用性。在富含P和N的处理中，更多经光漂白的底物被转化为细菌细胞。这些结果表明，养分的可利用性可能会影响CDOC的生物介导归宿（新生物量与呼吸作用）。
