Abstract: The present invention relates to an improved and efficient method for simultaneous monitoring of abundance of individual mutants of a microbe in mixed populations where insertion of a known transposon in the genome of a microbe such that each mutant caries a single transposon insertion, isolating the genomic DNA of the mixed population of mutants, fragmenting the same with a frequently cutting restriction enzyme, ligating a double standard adapter to the genomic DNA fragments, amplifying the DNA fragments adjoining transposon insertions thereby generating a set of DNA fragments corresponding only to mutated genes resolving the said amplified DNA fragments followed by comparing the intensity of DNA fragments obtained from population of mutants before selection with that obtained from the population subjected to selection and finally sequencing the DNA fragments that change in abundance to identify the mutated genes.