History

Many strains of S. mutans caused dental plaque patients through the world. Various genotypes of S. mutans have been found in salivation, and dental biofilm. This study conducted in Babylon province middle of Iraq in 2021-2022. Fifty mouth wash samples were collected from patients suffering from severe teeth decay. The aim of study to phenotypic and genotypic the strains of S.mutants. The result shown growth of S.mutans colonies on MSB agar were characterized by special colony morphology, rough, dark blue color. The specific primer pair was successfully amplified partial sequence of dexA gene of 8 colonies pre-identified as S.mutans on phenotypic and biochemical tests. The amplification shown PCR band with size 614bp. Genotyping S.mutans isolates based on Sequence analysis shown nine strains of S.mutans were subjected for sequence analysis; the results of sequence were subjected for multiple alignments by Geneious prime software. Four variants were observed with high frequency, variant 1 wild type T mutant to G (T>G) with frequency 33.4%; variant 2 C>t (44.4%); variant 3 A>C (66.6%) and Variant 4 C>T (44.4%). The Frequency values included homozygous mutation and heterozygous mutation. The final finding that S.mutants undergo high microevolution and produce many genotypes , this genotypes considered as risk factor in disease disappeared and treatment.