Characterization of a Red Bacterium Strain Isolated from Root Nodule of Faba Bean (Vicia faba L.) for Growth and Pigment Production

An unidentified red bacterium strains isolated as endophyte of root nodule of faba bean, when characterized for morphological, microscopic, biochemical and molecular (16SrDNA sequence) features were identified as a novel strain of Serratia marcescens. The strain formed small red colony size measuring 2-3 mm in diameter on Glucose Mannitol Tryptone Yeast Extract (GMTYE) agar medium. Under scanning electron microscopy, the single cell rods measured 3.55 - 4.18µm x 0.48µm - 0.68µm. The bacterium strain could efficiently utilize a wide range of carbohydrates (monosaccharide, disaccharide and polysaccharide) both for growth and pigmentation. It's preferred simple form of organic nitrogen for growth and pigmentation but was unable to utilize inorganic sources of nitrogen. The bacterium could grow over a wide range of medium pH (4.00-11.00) and temperature (20-37°C) and NaCl concentration (0.5-2.0%) but optimal growth and pigmentation were observed in the GMTYE medium of pH (6.00-7.00) containing NaCl at 0.5 percent level and at 28°C of incubation temperature.