Effects of long-term treatment with acetylene on nitrogen-fixing microorganisms.
AUTOR(ES)
David, K A
RESUMO
Long periods of experimental incubation with acetylene led to a multifold enhancement of acetylene-reducing activity in Anabaena cylindrica, Anabaenopsis circularis, Rhodospirillum rubrum, and Azotobacter vinelandii. Rates of acetylene reduction showed a gradual increase and reached a peak after 2 to 6 h of continuous incubation under acetylene. Thereafter, enzyme activity rapidly declined. A similar enhancement of ethylene production was observed when pretreatment with acetylene was interrupted periodically by a brief exposure to ambient (or oxygen-free) atmosphere without acetylene although the decline of acetylene-reducing activity was less rapid. Pretreatment with acetylene depressed photosynthetic 14CO2 fixation and 15N2 incorporation in Anabaena cylindrica. It is concluded that assessments based on long-term experimental incubation with acetylene may grossly overestimate the actual quantities of fixed nitrogen in the field.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=242724Documentos Relacionados
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