DMSP-lyase activity in five marine phytoplankton species: its potential importance in DMS production
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Activity of DMSP-lyase, which cleaves dissolved DMSP (henceforth DMSPd-lyase), was examined in five axenically cultured phytoplankton species, including both DMSP-producing and non-DMSP-producing species. High DMSPd-lyase activity was found in two DMSP producers, Heterocapsa triquetra strain NIES-7 and Scrippsiella trochoidea strain NIES-369 (Dinophyceae). The DMS production rates at 100 nM DMSPd were 0.5 fmol cell−1 min−1 for H. triquetra and 0.3 fmol cell−1 min−1 for S. trochoidea. In a non-DMSP producer, Heterosigma akashiwo strain NIES-6 (Raphidophyceae), the DMSPd-lyase activity was not found. Two DMSP-producing Prymnesiophyceae species, Isochrysis galbana strain CCMP-1323 and Gephyrocapsa oceanica strain NIES-353, did not show any obvious activity either, in contrary to other authors' findings on Phaeocystis sp., another DMSP-producing Prymnesiophyceae species. The comparison of the DMSPd-lyase activity of the two Dinophyceae species with bacterial DMSP consumption and DMS production activity in Tokyo Bay showed that the DMSPd-lyase activity of H. triquetra and S. trochoidea could be an important mechanism for DMS production during their blooms.
KeywordsPhytoplankton Production Rate Production Activity Potential Importance Phytoplankton Species
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