High hopanoid/total lipids ratio in Frankia mycelia is not related to the nitrogen status.
Vesicles are specific Frankia structures which are produced under nitrogen-limiting culture conditions. Hopanoids are the most abundant lipids in these vesicles and are believed to protect the nitrogenase against oxygen. The amounts and quality of each hopanoid were estimated in different Frankia strains cultivated under nitrogen-depleted and nitrogen-replete conditions in order to detect a possible variation. Studied Frankia strains nodulating Eleagnus were phylogenetically characterized by analysis of the nifD-K intergenic region as closely related to genomic species 4 and 5. Phylogenetically different strains belonging to three infectivity groups were cultivated in the same medium with and without nitrogen source for 10 d before hopanoid content analysis by HPLC. Four hopanoids together accounted for 23-87% and 15-87% of the total lipids under nitrogen-replete and nitrogen-depleted culture conditions, respectively. Two of the hopanoids found, bacteriohopanetetrols and their phenylacetic acid esters, have previously been described in Frankia Two new hopanoids, moretan-29-ol and a bacteriohopanetetrol propionate, have also been identified. The moretan-29-ol and bacteriohopanetetrols were found to be the most abundant hopanoids whereas the bacteriohopanetetrol propionate and phenylacetates were present at a concentration close to the limit of detection. The ratio of (bacteriohopanetetrols + moretan-29-ol)/(total lipids) varied in most of the strains between nitrogen-depleted and nitrogen-replete culture conditions. In most of the strains, the hopanoid content was found to be slightly higher under nitrogen-replete conditions than under nitrogen-depleted conditions. These results suggest that remobilization, rather than neosynthesis of hopanoids, is implicated in vesicle formation in Frankia under nitrogen-depleted conditions.
Nalin
Renaud
R
Laboratoire d'Ecologie Microbienne, UMR CNRS 5557, Université Lyon 1, 43 Bld du 11 Novembre 1918, 69622 Villeurbanne Cedex, France1.
Putra
Surya Rosa
SR
Université Louis Pasteur/CNRS, Institut Le Bel, 4 rue Blaise Pascal, 67070 Strasbourg Cedex, France2.
Domenach
Anne-Marie
AM
Laboratoire d'Ecologie Microbienne, UMR CNRS 5557, Université Lyon 1, 43 Bld du 11 Novembre 1918, 69622 Villeurbanne Cedex, France1.
Rohmer
Michel
M
Université Louis Pasteur/CNRS, Institut Le Bel, 4 rue Blaise Pascal, 67070 Strasbourg Cedex, France2.
Gourbiere
François
F
Laboratoire d'Ecologie Microbienne, UMR CNRS 5557, Université Lyon 1, 43 Bld du 11 Novembre 1918, 69622 Villeurbanne Cedex, France1.
Berry
Alison M
AM
Department of Environmental Horticulture, University of California, Davis, CA 95616, USA3.
D000192:Actinomycetales / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D022162:Cytoplasmic Vesicles / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D008055:Lipids / Q000032:analysis* / Q000737:chemistry; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000378:metabolism*; D010802:Phylogeny; D013045:Species Specificity; D014315:Triterpenes / Q000032:analysis* / Q000737:chemistry
D017931:DNA Primers; D008055:Lipids; D014315:Triterpenes; D009584:Nitrogen