Yersinia pestis, the etiologic agent of plague and a member of the family Enterobacteriaceae, is a gramnegative, non-spore forming, non-motile coccobacillus that grows within a temperature range of 4 to 400C and optimum pH range of 7.2 to 7.6 . This beyond infamous bacterium is responsible for three devastating pandemics throughout history namely the Justinian's plague, the Black Death and the Modern plague . The plague is zoonotic as it spreads from rodents as a natural reservoir to humans using fleas as the vector . Bites of fleas during blood-meal to humans, direct contact with a mucous membrane or damaged skin, inhalation of aerosolized air droplets cause transmission of the pathogenic bacterium to human . It causes the death of the individual within a week if left untreated for bubonic form and even less than a week for septicemic form and pneumonic form. The rapid development of bacterial biofilm inside the digestive tract of flea helps Y. pestis to adapt to a unique life stage for effective transmission . For its high similarity in the genomic level with Y. pseudotuberculosis, Y. pestis is thought to be a recently emerged clone of it , . The USA, the former Soviet Union and Japan developed Y. pestis as a biological weapon during the 20th century .