ANALYSIS OF EXOPOLYSACCHARIDE OF IG-1 (CITROBACTER FREUNDII) ISOLATED FROM EARTHWORM UNDER DIFFERENT PHYSIOLOGICAL CONDITIONS

Abstract

The strain IG-1 (Citrobacter freundii) previously isolated (from the internal surface of earthworms) and characterized at morphological, biochemical and molecular level was used for both qualitative and quantitative analysis of exopolysaccharide (EPS) under different physiological conditions such as temperature, different media and agitation. Citrobacter freundii (IG-1) was screened for EPS production by using Congo red agar method and appearance of dark brown color was considered as positive result. The influence of different temperatures on production of bacterial EPS was determined by incubating cultures at 4ºC, 37ºC, 45ºC temperature and EPS was extracted. Exopolysaccharide content was also determined by using different growth media such as L-broth and M9 under shaking and non- shaking conditions. After extraction, EPS were quantified in terms of protein and carbohydrate contents. In general it was observed that higher amount of EPS was produced in LB media, in static conditions and at 37?C respectively. Similar trend was observed for protein and carbohydrate content of EPS. Seeds were inoculated with cultures to observe plant growth potential of microbes. Seeds were also subjected to salt stress. Inoculation with IG-1 improved (24%) seed germination in salt stress as compare to non-inoculated control. Bacterial inoculation significantly improved the shoot length in the presence of salt stress. Similar pattern was recorded for root length and seedling length. Microscopic examination of cross section of roots was done. Root sections stained with Sudan III appear red from center while Potassium iodide stained roots appeared dark from center.