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THE UPTAKE AND ASSIMILATION OF AMMONIA BY NEOCOSMOSPORA VASINFECTA
Author(s) -
BUDD K.,
HARLEY J. L.
Publication year - 1962
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1962.tb06293.x
Subject(s) - ammonia , chemistry , mycelium , ammonia production , sodium , potassium , inorganic chemistry , environmental chemistry , botany , biochemistry , organic chemistry , biology
S ummary Ammonia uptake by low‐nitrogen mycelium of Neocosmospora is accompanied by an increase in the ammonia associated with the mycelium. This ammonia consists of two main fractions: the ‘exchangeable’ammonia, which is readily separated from the mycelium by cold, dilute solutions of potassium or sodium chloride, and the ‘residual’ammonia, which is retained by the mycelium under these conditions. The evidence indicates that the exchangeable ammonia represents ammonia held on exchange‐sites plus ammonia associated with a water‐space. At 25° C both fractions reach maximum levels in the mycelium within 10 minutes. The relative proportions of the exchangeable and residual ammonia depend upon conditions, especially the external pH and ammonia concentration. The maximum level attained by the residual ammonia is markedly reduced in the absence of oxygen or the presence of sodium azide of 2,4‐dinitrophenol, but none of these treatments reduces the exchangeable ammonia level. Increase in the level of residual ammonia in the cells thus appears to depend upon normal aerobic respiration but there is no evidence that this is true of exchangeable ammonia. Both exchangeable and residual ammonia decline in the mycelium during incubation in the absence of external ammonia after a period of ammonia absorption. They are therefore available for further reactions in the cell and may be normal intermediates in the synthesis of organic nitrogen compounds from external sources of ammonia.