Abstract
The present study involves phylogenetic analysis of distinguished bacterial population essentially grouped into functional attributes, namely nitrogen fixation and quorum sensing. The basis of this analysis are protein sequences of NifH (nitrogenase reductase), LuxA (Luciferase alpha subunit) and LuxS (S- ribosyl homocysteine lyase) from 30, 17, 25 species of bacteria respectively. These bacteria show vast diversity in terms of habitat mode of survival pathogenicity. Phylogenetic analysis gives an insight into the evolution and interrelationships of these microbial species. GeneBee, ClustalW and Phylip softwares were found to be satisfactory for the chosen work. Phylogenetic trees were constructed in the form of Cladograms, Phylograms and Unrooted radial trees. According to the results obtained, the most highly evolved group of organisms with respect to their nitrogenase reductase protein is that of Desulfovibrio vulgaris and Chlorobium phaeobacteriodes . Bacillus thuringiensis and Bacillus subtilis hold the most highly evolved forms of LuxS protein. Also knowledge abtained from the motif pattern analysis between Bradyrhizobium japonicum and Rhizobium leguminosarum NifH protein sequence are conserved and further analysis may show that there may be quorum sensing mediated gene regulation in host bacterium interaction. Phylogenetic analyses, thus, on the basis of highly conserved protein domains, universal in their existence, can provide a preamble to the actual 16S-rRNA based phylogeny or genomic analyses of phylogeny carried out in the wet lab.
Highlights
Nitrogen Fixation Nitrogen makes up about 14% of the total dry weight of a bacterial cell, majorly concentrated in the proteins and nucleic acids of the cell
Phylogeny of Nitrogen-Fixing Bacteria on the basis of NifH protein Nitrogenase reductase is a functionally constant protein catalyzing N2 reduction, which is found in many phylogenetic lineages of Archaeabacteria, Proteobacteria, Cyanobacteria, Actinobacteria and Diazotrophs
Rectangular Cladogram, an output of Proml. This type of tree only represents a branching pattern, i.e., its branch lengths do not represent time.Fig.4 is a Phylogram of nifH gene, a phylogram is a phylogenetic tree that explicitly represents the rate of evolution of organisms; where the number of character changes in the protein is directly proportional to branch lengths
Summary
Nitrogen Fixation Nitrogen makes up about 14% of the total dry weight of a bacterial cell, majorly concentrated in the proteins and nucleic acids of the cell. Some important groups of bacteria possess the ability to utilize gaseous nitrogen from the atmosphere. The atmosphere constitutes about 78.9% of nitrogen gas, which is significantly higher than other gases. The nitrogen cycle is one of the most important biogeochemical cycles, maintaining the atmospheric balance of the universe [18]. The process of converting nitrogen in its gaseous form into ammonia is termed as nitrogen fixation, and is catalyzed by an enzyme called Nitrogenase (E.C 1.18.6.1). Biological nitrogen fixation can be represented by the following equation, in which two moles of ammonia are produced from one mole of nitrogen gas, at the expense of 16 moles of ATP and a supply of electrons and protons: N2 + 8H+ + 8e- + 16 ATP = 2NH3 + H2 + 16ADP+16 Pi
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