Symbiotic microorganisms

The nature of the diet sets the basic pattern of metabohsm. There is a need to process the products of digestion of dietary carbohydrate, lipid, and protein. These are mainly glucose, fatty acids and glycerol, and amino acids, respectively. In ruminants (and to a lesser extent in other herbivores), dietary cellulose is fermented by symbiotic microorganisms to short-chain fatty acids (acetic, propionic, butyric), and metabohsm in these animals is adapted to use these fatty acids as major substrates. All the products of digestion are metabohzed to a common product, acetyl-CoA, which is then oxidized by the citric acid cycle (Figure 15-1). 

This pathway is also important for ruminant animals, which are dependent on symbiotic microorganisms to break down their food. The microorganisms produce large amounts of propionic acid as a degradation product, which the host can channel into the metabolism in the way described. 

Symbiotic Microorganism. Tetrodotoxin is the product of some microorganism which lives symbiotically with these particular animals. 

Thousands of bioactive compounds that have fascinating potentials to develop as nutraceuticals have been identified from marine sources. This chapter investigates the possibility of developing nutraceuticals from bioactive compounds, identified from marine sponges and symbiotic microorganisms. 

Isolation and culture of putative symbiotic microorganisms to obtain the bioactive metabolites isolated from the invertebrate-microbe assemblages has been particularly problematic. It has been estimated that only 1% of marine microbes can be isolated and fermented using techniques modified to approximate marine conditions. However, to address this problem, several groups have used differential fractionation or flow cytometric techniques to separate populations of extracellularly associated microorganisms from invertebrate host cells. Chromatographic and spectroscopic analyses of the enriched cell fractions have been used to determine which cell type is producing the compounds. The assumption is that the metabolites are produced in the cell types in which they are detected. 

Signals for communication between plants and symbiotic microorganisms (N-fixing Rhizobia or mycorrhizal fungi)... 

Calycnlin A (38) is an extraordinary metabolite composed of C28 fatty acid and two y-amino acids isolated from the sponge Discodermia calyx. It is not only highly antifnngal and antitnmor bnt also a potent cancer promoter that was fonnd to be cansed by potent inhibition of protein phosphatases 1 and 2A (1). More than 15 calycnlin derivatives were isolated from several marine sponges, which indicates the involvement of symbiotic microorganisms in the prodnction of calycnhns (6). 

A variety of 3-alkylpiperidine-derived compounds have been obtained from sponges belonging to five families of the order Haplosclerida (26). They show a range of bioactivities, for example, cytotoxic, antimalarial, and antifouling. It is likely that 3-alkylpiperidines are produced by sponge cells but not by symbiotic microorganisms. 

Kumari, R., Pham, G.H., Singh. A., Bhoon, Y.K., Srivastava, A.K. and Varma, A. (2004). Biotechnological Processes for Transfer Technology of Medicinal Plants Mediated hy Symbiotic Microorganisms (From Lab to Fields Novel Concepts.). Souvenir, World Herbal Expo, Bhopal, India. 

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