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N-Acetylglucosamine Dynamics in Freshwater Environments: Concentration of Amino Sugars, Extracellular Enzyme Activities, and Microbial Uptake

Jiri Nedoma, Jaroslav Vrba, Josef Hejzlar, Karel Simek and Vera Straskrabova
Limnology and Oceanography
Vol. 39, No. 5 (Jul., 1994), pp. 1088-1100
Stable URL: http://www.jstor.org/stable/2838474
Page Count: 13
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N-Acetylglucosamine Dynamics in Freshwater Environments: Concentration of Amino Sugars, Extracellular Enzyme Activities, and Microbial Uptake
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Abstract

As a first to the study of the dynamics of amino sugars in freshwater environments, we measured microbial uptake of N-acetylglucosamine and hydrolysis of $4-MUF-N-acetyl-\betha-glycosaminide$ by extracellular enzymes in fishponds, reservoirs, backwaters, and lakes. Amino sugars were present in all localities and comprised up to several percent of both dissolved and particulate organic matter. Processes involving N-acetylglucosamine (extracellular enzymes, microbial uptake) were also detected in all localities; their potential rates accounted for $\sim 10-100%$ of the rates of analogical processes involving glucose and were correlated with dissolved organic C and with general microbial activity. Two types of $4-MUF-\betha-N-acetylglucosaminidases$ (high and low affinity) were distinguished kinetically. The activity of the high-affinity enzyme was tighly correlated with variables coupled to bacterial activity. In fishponds, uptake of N-acetylglucosamine by diatoms and cyanobacteria was detected via autoradiography.

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