Significance of Bacterial Exoenzymes in Organic Matter Cycling in the Antarctic Ocean

从初级生产者到细菌的碳耦合可以显著影响海洋中有机质垂直通量的模式。由于细菌在吸收颗粒之前必须水解颗粒，因此细菌的外水解酶必须在颗粒有机物质进入微生物循环的碳通量中发挥核心作用。细菌外水解酶的表达受底物浓度的调节，因此可能在缺乏颗粒和聚合物的水中停止。在高纬度水域，在漫长的极夜期间没有浮游植物的产生。要验证的假设是，在南极的冬季，细菌的外水解酶停止生产。因此，在早春开花期间产生的颗粒和聚合物不能被细菌利用。当有机物积累到临界水平时，就会表达外水解酶；因此，颗粒有机物和细菌之间的耦合变得很强。现场和实验室操作将检查调节外水解酶活性的环境线索。这一知识将有助于理解南大洋有机物循环途径中的生物生产机制和变异性。

Coupling of carbon from primary producers to bacteria can significantly influence the patterns of vertical flux of organic matter in the ocean. Because bacteria must hydrolyze particles before uptake, bacterial exohydrolases must assume a central role in carbon flux from particulate organic matter into the microbial loop. The expression of bacterial exohydrolases is regulated by substrate concentration and therefore may cease in waters depleted of particles and polymers. In high latitude waters there is no phytoplankton production during the protracted polar night. The hypothesis to be tested is that during the Antarctic winter, the production of bacterial exohydrolase ceases. Therefore, particles and polymers produced during the early spring bloom cannot be utilized by bacteria. Exohydrolases are expressed when organic matter accumulates to a critical level; consequently, the coupling between particulate organic matter and bacteria becomes strong. Field and laboratory manipulations will examine environmental cues which regulate exohydrolase activities. This knowledge should contribute to the understanding of biological production mechanisms and variability in the pathways of organic matter cycling in the Southern Ocean.