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In situ enzyme activity in the dissolved and particulate fraction of the fluid from four pitcher plant species of the genus Nepenthes.

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Publication date 2011
Author Takeuchi Yayoi, Salcher Michaela M, Ushio Masayuki, Shimizu-Inatsugi Rie, Kobayashi Masaki J, Diway Bibian, von Mering Christian, Pernthaler Jakob, Shimizu Kentaro K,
Project Transcriptomic analysis of polyploid species using second generation sequencers: how are they tolerant of broader range of environmental stresses?
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Original article (peer-reviewed)

Journal PloS one
Volume (Issue) 6(9)
Page(s) 25144 - 25144
Title of proceedings PloS one
DOI 10.1371/journal.pone.0025144

Abstract

The genus Nepenthes, a carnivorous plant, has a pitcher to trap insects and digest them in the contained fluid to gain nutrient. A distinctive character of the pitcher fluid is the digestive enzyme activity that may be derived from plants and dwelling microbes. However, little is known about in situ digestive enzymes in the fluid. Here we examined the pitcher fluid from four species of Nepenthes. High bacterial density was observed within the fluids, ranging from 7×10(6) to 2.2×10(8) cells ml(-1). We measured the activity of three common enzymes in the fluid: acid phosphatases, β-D-glucosidases, and β-D-glucosaminidases. All the tested enzymes detected in the liquid of all the pitcher species showed activity that considerably exceeded that observed in aquatic environments such as freshwater, seawater, and sediment. Our results indicate that high enzyme activity within a pitcher could assist in the rapid decomposition of prey to maximize efficient nutrient use. In addition, we filtered the fluid to distinguish between dissolved enzyme activity and particle-bound activity. As a result, filtration treatment significantly decreased the activity in all enzymes, while pH value and Nepenthes species did not affect the enzyme activity. It suggested that enzymes bound to bacteria and other organic particles also would significantly contribute to the total enzyme activity of the fluid. Since organic particles are themselves usually colonized by attached and highly active bacteria, it is possible that microbe-derived enzymes also play an important role in nutrient recycling within the fluid and affect the metabolism of the Nepenthes pitcher plant.
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