Sinorhizobium meliloti Bacteria Contributing to Rehabilitate the Toxic Environment

Nitrogen fixing microorganisms play a vital role in the rejuvenating the environment. A Sinorhizobium meliloti bacterium is one such microbe and has immense potential to rehabilitate the toxic environment that lies unexplored. The review highlights some of its uses in agriculture and environment. Figure 1: The symbiotic relationship between the plant and bacteria. Figure 2: The Nitrogen cycle depicting its transformations in the nature. Figure 3: The various types of nitrogen fixation. Citation: Chauhan A (2015) Sinorhizobium meliloti Bacteria Contributing to Rehabilitate the Toxic Environment. J Bioremed Biodeg 6: e164. doi:10.4172/2155-6199.1000e164 Volume 6 • Issue 2 • 1000e164 J Bioremed Biodeg ISSN: 2155-6199 JBRBD, an open access journal Page 2 of 2 and nutritional conditions. S. meliloti has been the subject of extensive genetic, biochemical and metabolic research. The sequencing of the strain Rm1021 genome provided a solid foundation for a number of molecular studies of the genetic basis of plant-bacterium interactions and of the response of S. meliloti to environmental stimuli. Strains of S. meliloti, as for other rhizobial species, are known to show different nodulation capabilities and phenotypic characteristics, such as salt and stress tolerance and exo-polysaccharide production. Despite the large number of genetic and molecular biology studies of the sequenced Rm1021 strain and its natural populations, little is known about the overall extent of metabolic diversity of Rm1021 and environmental strains. Consequently, clear evidence on possible functional and metabolic roles of the observed genomic polymorphism is still lacking. In past years, more attention has been focused on that part of bacterial genetic variation which is directly related to the phenotype. Sinorhizobium meliloti cells serve a significant role in the survival of many plant species and they also largely contribute to the environment. The atmosphere is composed of approximately 85% nitrogen and it is an essential element to most living organisms and their metabolic activities. But, nitrogen exists in the atmosphere as dinitrogen (N2) that is unusable by most plants and animals. S. meliloti cells in the environment form symbiotic relationships with leguminous plants and convert N2 into organic nitrogen. S. meliloti also serves as denitrifying agent that reduces nitrate and nitrite into free N2 in the environment (Figure 2). S. meliloti is unique and one of the first organisms to have a cluster of all four nitrogen oxide reductases (nap, nir, nor, nos) on the same chromosome. Denitrification can have hazardous effects such as a loss of biologically useful nitrogen, a buildup of N2O as a byproduct which contributes to acidic rain and a depletion of the ozone layer. However, denitrification conducted by S. meliloti cells can have positive effects as well if it is harnessed properly. For example, the N2O produced by denitrification can serve as a green-house gas that traps heat. The microbial denitrification can contribute significantly to the purification of waste water. Nitrogen-rich fertilizers have contributed to the pollution of ground water. This water is potentially hazardous to pregnant women and infants and thus scientists are considering using microbial denitrification in water treatment facilities to remove excess NO3. A bacterium isolated from soil (designated 9702-M4) synthesizes an extracellular polymer that facilitates the transport of such hydrophobic pollutants as polynuclear aromatic hydrocarbons, as well as the toxic metals lead and cadmium in soil [3-9]. This property of the organism if expedited can play a crucial role to purify the toxic soil and inhibit the health hazards. Conclusions S. meliloti has huge potential to reduce the toxicity from theenvironment so; there is need of enhancing the survival of noduleforming bacterium by improving competitiveness of inoculant strainsthere is need to extend host range of crops that can benefit frombiological nitrogen fixation. We should engineer microbes with highnitrogen fixing capacity for a healthy environment.References 1. Ba S, Willems A, de Lajudie P, Roche P, Jeder H, et al. (2002) Symbiotic andtaxonomic diversity of rhizobia isolated from Acacia tortilis subsp. raddiana inAfrica. Syst Appl Microbiol 25: 130-145. 2. Rogel MA, Ormeño-Orrillo E, Martinez Romero E (2011) Symbiovars in rhizobiareflect bacterial adaptation to legumes. Syst Appl Microbiol 34: 96-104. 3. Schneiker-Bekel S, Wibberg D, Bekel T, Blom J, Linke B, et al. (2011) Thecomplete genome sequence of the dominant Sinorhizobium meliloti field isolateSM11 extends the S. meliloti pan-genome. J Biotechnol 155: 20-33. 4. 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Gubry-Rangin C, Béna G, Cleyet-Marel JC, Brunel B (2013) Definition andevolution of a new symbiovar, sv. rigiduloides, among Ensifer meliloti efficientlynodulating Medicago species. Syst Appl Microbiol 36: 490-496. 9. Janecka J, Jenkins MB, Brackett NS, Lion LW, Ghiorse WC (2002)Characterization of a Sinorhizobium isolate and its extracellular polymerimplicated in pollutant transport in soil. Appl Environ Microbiol 68: 423-426.Host plantBacterial symbiontAlfalfaRhizobium melilotiCloverRhizobium trifoliiSoybeanBradyrhizobium japonicumBeansRhizobium phaseoliPeaRhizobium leguminosarumSesbaniaAzorhizobium caulinodans Table 1: Some of the host plant and their bacterial symbiont that fixes the nitrogen. Citation: Chauhan A (2015) Sinorhizobium meliloti Bacteria Contributingto Rehabilitate the Toxic Environment. J Bioremed Biodeg 6: e164.doi:10.4172/2155-6199.1000e164Submit your next manuscript and get advantages of OMICSGroup submissions