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Possible evidence for novel metabolism of nitrogen gas by a green alga
Author(s) -
Weathers Pamela J.,
Danielli James F.,
Bradley Peter M.,
Hebb Diane M.,
Miller Judith E.,
Pesano Rick L.
Publication year - 1984
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1984.tb06353.x
Subject(s) - diazotroph , kjeldahl method , nitrogen , cyanobacteria , chlorella , ethylene , chlorophyceae , metabolism , chemistry , nitrogen fixation , acetylene , heterocyst , botany , dilution , food science , environmental chemistry , biology , biochemistry , chlorophyta , algae , organic chemistry , bacteria , nitrogenase , thermodynamics , physics , genetics , catalysis
We report the isolation of a cukaryotic green alga ( Chlorella , strain WPI‐2) which accumulates large stores of nitrogen (N) during growth in N‐free medium and seems to incorporate 14 N 2 , yet does not reduce acetylene to ethylene. Total N accumulation during growth on N‐free medium and in gases free of combined N was measured by three methods: Kjeldahl, oxidative pyrolysis via chemiluminescence (Antek N analyzer), and Dumas (Coleman N analyzer). Increases in N ranging from 22–64%± 1% were observed. Isotope dilution studies using cells labelled with 15 NO 3 ‐ and then shifted to 14 N 2 in N‐free medium showed dilution of the 15 N isotope by 14 N from 5.67 to 5.32%± 0.05%. Using a variety of conditions, we were unable to demonstrate the reduction of acctylene to ethylene by WPI‐2, although diazotrophic cyanobacteria gave positive results. Although the data on WPI‐2 are not conclusive in establishing this alga as a diazotroph, the data do suggest that within the Chlorophyceae there may exist a novel form of nitrogen gas metabolism.