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Aquatic Microbial Ecology

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AME 69:93-99 (2013)  -  DOI:

Extracellular peptidase and carbohydrate hydrolase activities in an Arctic fjord (Smeerenburgfjord, Svalbard)

Andrew D. Steen1,3,*, Carol Arnosti2

1Center for Geomicrobiology, Aarhus University, 8000 Aarhus C, Denmark
2Department of Marine Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
3Present address: Department of Microbiology, University of Tennessee, Knoxville, Tennessee 37996, USA

ABSTRACT: Measurements of the spectrum of extracellular enzymes present in an environment can indicate the nature of organic substrates available to microorganisms. We report the activities in an Arctic fjord (Smeerenburgfjord, Svalbard) of the extracellular carbohydrate hydrolases α-galactosidase, β-glucosidase, and chitobiase, and the extracellular peptidases leucyl aminopeptidase, trypsin, and chymotrypsin. Among the carbohydrate hydrolases, β-glucosidase had the highest potential activity. Although extracellular leucyl aminopeptidase is frequently assayed in marine systems, activities of other peptidases have only rarely been reported. Peptidase activities were higher than carbohydrate hydrolase activities by approximately 2 orders of magnitude. Activities of leucyl aminopeptidase (an exopeptidase which cleaves terminal residues from a protein) were higher than trypsin and chymotrypsin (both endopeptidases which cleave interior bonds). In contrast to previous measurements from coastal, temperate environments, potential activity of leucyl aminopeptidase in Smeerenburg was higher than that of the endopeptidases trypsin and of chymotrypsin. These results suggest that leucyl aminopeptidase may not always be a reliable proxy for the total peptidolytic potential of microbial communities.

KEY WORDS: Extracellular enzymes · Microbial loop · Proteinase · Beta-glucosidase · Chitinase

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Cite this article as: Steen AD, Arnosti C (2013) Extracellular peptidase and carbohydrate hydrolase activities in an Arctic fjord (Smeerenburgfjord, Svalbard). Aquat Microb Ecol 69:93-99.

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