Specific long-chain fatty acids promote optimal growth of Frankia: accumulation and intracellular distribution of palmitic and propionic acid |
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Authors: | Shawky Selim Sandrine Delacour Jaime Schwencke |
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Institution: | (1) Biotechnologie des Symbioses Forestières Tropicales, ORSTOM/CIRAD Forêt. 45 bis Ave. de la Belle Gabrielle, F-94736 Nogent sur Marne Cedex, France tel. +33-1-4394-4410; Fax +33-1-4394-4329 or +33-1-4394-4361, FR |
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Abstract: | Frankia isolates from nodules of the genera Casuarina (BR, S21, Thr), Allocasuarina (Allo2), and Gymnostoma (G80) were found to grow exponentially with high biomass yield and minimal sporangia formation in stirred propionate mineral
medium when supplemented either with 2.4 μM palmitic acid (C16:0), pentadecanoic (C15:0), heptadecanoic (C17:0), or linoleic
(C18:2, cis 9, 12) fatty acids. Strains also grew with lauric (C12:0) or myristic (C14:0) acids, but gave lower biomass yield. Stearic
acid (C18:0) produced a good biomass yield, but cultures slowly accumulated sporangia; oleic acid (C18:1, cis-9) was detrimental to growth. Caprylic (C8:0) or capric (C10:0) acids proved to be prejudicial for long-term storage of Frankia strains. In experiments using labeled 1,2-dipalmitoyl phosphatidylcholine and palmitic acid, radioactivity bound rapidly
to the insoluble, but solvent-extractable fraction of Frankia cells. In contrast, label from propionic acid accumulated in the cytosolic fraction. Therefore, the beneficial effect of
some specific phospatidylcholines or free fatty acids on Frankia growth appears to result from their utilization as building blocks for the membrane, suggesting that membrane biosynthesis
may be the limiting step for Frankia growth in unamended propionate mineral medium.
Received: 9 October 1995 / Accepted: 24 February 1996 |
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Keywords: | Frankia growth Fatty acids Palmitic acid accumulation Phosphatidylcholine accumulation Membrane biosynthesis N2 fixation Casuarina |
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