Flavonoids influence growth and saccharide metabolism of Rhizobium meliloti

Supplementation of the growth media with flavonoids, viz. naringenin, flavo ne, quercetin and syringaldehyde, a phenolic compound and alfalfa seed exud ate, differently affected the growth and saccharide metabolism of Rhizobium meliloti. Quercetin increased while syringaldehyde, flavone and alfalfa ex udate decreased the growth and protein content of R. meliloti cells. Naring enin had no effect on growth and protein content though it increased the ex opolysaccharide production. Application of naringenin increased the activit ies of enzymes of the citrate cycle and the 6-phosphogluconate pathway, the major pathways of sugar metabolism in fast growing rhizobia, and decreased activities of glycolytic enzymes. The activities of enzymes of the pentose phosphate pathway remained unaffected by various treatments.