A Rifampicin-resistant (rpoB) Mutation in Pseudomonas Stutzeri Leads to Enhance the Biosynthesis of Secondary Metabolites and Nitrogen Fixation to Adapt Against Harsh Environments

Abstract The rpoB gene encoding for β subunit of RNA polymerase has been targeted as a mutation for importance to Rifampicin Resistant (Rifr) phenotype of the bacteria. The study aimed to learn the mutational processes, location of the mutation and metabolic capabilities among the strains and nitrogen fixation capacity of the bacteria for acclimatization in the environment. In this study, wild type and 5 rpoBRifr mutants of Pseudomonas stutzeri such Q518R, D521Y, D521V, H531R and I614T were characterized and used as a test system. The robust Rifr phenotype of P. Stutzeri was associated only with base replacements of the amino deposits. Considering these facts, the current study was conducted to investigate the effect of rpoB mutants on metabolism, a wild-type and five distinct Rifr mutants of P. stutzeri for utilization of 95 substrates through Biolog GN2 MicroPlates. Several oxidized substrate usage patterns occurred in the Rifrmutants, use of carboxylic and amino acids significantly increased in various rifr mutants than that of wild type. The assimilation of carbon and nitrogen sources of rifr mutants reveals that the organism maintains the adaptation in nutritionally complex environments. Acetylene reduction assay carried out at different times it revealed that considerable variability was found in the nitrogen fixation ability among the studied strains. The highest nitrogenase activity was determined rifr mutant D521V that was of 2176.6 nmole ethylene/h/mg protein. Base substitution at different sites of rifrmutatnts caused nucliec acid transition, is responsible for codon change into the amino acids which differ carbon and nitrogen utilization. The assimilation of carbon and nitrogen sources of Pseudomonas stutzeri and its rifr mutants ensures that the organism maintains the adaptation in nutritionally complex environments and can fix nitrogen.