Production of cell-associated polysaccharides of Rhizobium fredii USDA205 is modulated by apigenin and host root extract.
Rhizobium fredii USDA205 cells were cultured in the presence of 4',5,7-trihydroxyflavone (apigenin), a compound that has been shown to induce the nod genes and other symbiosis-related genes in R. fredii. The cell-associated polysaccharides were then extracted with hot phenol/water, separated by repetitive gel filtration chromatography, and analyzed by polyacrylamide gel electrophoresis, nuclear magnetic resonance spectrometry, high-performance anion-exchange chromatography, and gas chromatography. These analyses showed that apigenin effects a modulation in the production of some cell-associated bacterial polysaccharides: 1) The production of a glucan is severely attenuated; 2) the lipopolysaccharide O antigen is modified in composition and M(r) distribution; and 3) the ratio of two extracted polysaccharides, which are structurally analogous to group II K antigens (capsular polysaccharides), is altered. Similar effects resulted from the inclusion of host plant root extract in the growth medium.
Complex Carbohydrate Research Center, University of Georgia, Athens 30602-4712.
B L
BL
Reuhs
J S
JS
Kim
A
A
Badgett
R W
RW
Carlson
D020843:Chamomile; D002849:Chromatography, Gas; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D005419:Flavonoids / Q000494:pharmacology*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D009682:Magnetic Resonance Spectroscopy; D009822:Oils, Volatile / Q000494:pharmacology*; D010936:Plant Extracts / Q000494:pharmacology*; D010946:Plants, Medicinal; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis* / Q000737:chemistry; D012231:Rhizobium / Q000235:genetics / Q000378:metabolism*; D013559:Symbiosis / Q000235:genetics
D005419:Flavonoids; D009822:Oils, Volatile; D010936:Plant Extracts; D011135:Polysaccharides, Bacterial