The yellow color of Flavobacteria is due to the presence of carotenoids and flexirubin-type pigments. These complex chemical structures have shown to produce antioxidant properties, as well as antibacterial activity. The KOH test and reverse-phase high performance liquid chromatography (HPLC) was used to characterize carotenoid and flexirubin pigment production in three strains of Flavorbacteria: FR 87, FR Y, and FR 93. Optimization of pigment and separation was performed by quant-prep HPLC. Separation of four pigment fractions from each strain was attained using semi-prep HPLC. Antibacterial activity of the pigment fractions was tested using a MTT Assay. Fexirubin biosynthesis genes, darA and darB, of related pigment producing Flavobacteria were used to compare flexirubin pigments in FR 87. The three strains were determined to produce the carotenoid, Zeaxanthin. FR 87 produced 13 flexirubin pigments, FR Y produced 14 flexirubin pigments and FR 93 produced 20 flexirubin-type pigments. It was determined that compounds in all three strains demonstrated antibacterial activity. The flexirubin biosynthesis gene, darA, is 89.9% similar to Flavobacterium johnsoniae, and 73.2% similar to Flavobacterium psychrophilum.
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