Evaluation of a Nitrate-Assimilating Bacterium for Potential Use in Nitrate Bioremediation

Abstract

Increasing levels of nitrate (NO3-N) in water resources have brought about the need to find ever more versatile forms of NO3-N removal from contaminated water. The ability of several microorganisms to transform NO3-N has been embraced as an economical form of bioremediation. Free cell and immobilized forms of Methylobacterium fujisawaense ATCC® No. 35065 (M. fujisawaense) were used in this study for NO3-N removal in batch settings. NO3-N removal results were as high as 100% for freely suspended cells after 96 hours and 95% for immobilized cells also after 96 hours. Statistical analyses found no significant difference in overall NO3-N removal rates between free cell and immobilized systems. These findings suggest that the organism is capable of up to full assimilation of 10 mg/L NO3-N in certain settings. The findings also suggest that the NO3-N assimilating ability of M. fujisawaense of 10 mg/L NO3-N is not greatly altered by immobilization.