To achieve significant results in the study of any organism, it is necessary to investigate the genetic material, which is decoded from the sequence of the species, in order to find out what changes in the genome can lead to certain consequences. Hence, this work aims to study certain aspects of the genome of probiotic yeast strains and clinical isolates of the same yeast, particularly mitochondrial copy numbers and their mutations and compare the commercial, mycosis, and non-mycosis isolates of S. boulardii. Throughout this thesis work, 14 isolates of S. cerevisiae yeast have been analyzed for mitochondrial DNA copy numbers and their mutations. Median coverages of mtDNA and chromosomes, petite frequency, and their correlation coefficient can be calculated to achieve the set goal