Biomedical Engineering Reference
In-Depth Information
Figure10.5 Rootnoduleformation
ammonia, or the ammonium ion, has been formed it may be transferred to the
amino acid, glutamate, to produce glutamine. This transfer is frequently invoked
throughout metabolism. This is not the only route for the assimilation of the
amino group into metabolic pathways; the synthesis of the purine derivative,
allantoin or allantoic acid, being a less heavily used alternative. These pathways
are described in Chapter 2. Nitrogen fixation involving Rhizobium has been the
focus of the preceding discussion, but the family of aerobic, Gram positive bac-
teria, actinomycetes, is another group carrying out the same function using a
similar mechanism. These may form a network of aerial or substrate hyphae
resembling a structure commonly associated with that of fungi. These bacteria
may form a close association, called actinorhizae, with the roots of a number of
plants which tend to be woody, or shrub like in nature.
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