Bacterial ectoenzymes in marine waters: activity ratios and temperature responses in three oceanographic provinces. Limnol. Oceanogr

• Main Authors: James R. Christian, David M. Karl
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1995
• Subjects: Antarctic; Pacific; Southern Ocean; Antarc*
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.320.3394; http://aslo.org/lo/toc/vol_40/issue_6/1042.pdf

Ectoenzymatic hydrolysis is a crucial first step in bacterial utilization of polymeric dissolved organic matter (DOM). Variation in the relative activities of different enzymes can indicate seasonal and geographic variation in the mode of bacterioplankton nutrition. We found that relative activities of leucine aminopeptidase and P-glucosidase in seawater varied significantly among three oceanic regions: the subtropical North Pacific, the equatorial Pacific, and the Southern Ocean. The temperature responses of these enzymes also vary significantly among these three regions, suggesting distinct bacterial phenotypes with distinct isozymes. Our results suggest a latitudinal trend in bacterial carbon and nitrogen utilization, with significant synthesis of cell constituents from glucose and ammonium in equatorial waters but little such de novo synthesis in Antarctic waters. The observed patterns have important implications for the parameterization of secondary production and nutrient regeneration in global production models and for understanding the role of DOM in global carbon and nitrogen fluxes. Fluorogenic tracers of ectoenzymatic activity in marine and freshwaters have now been in USC for more than a decade (Hoppe 1983; Somvillc and Billcn 1983). Because