ABSTRACT
Since the existence of earth, microorganisms also became an indispensable part of biosphere. Till today, microorganisms are still surviving by making some changes on their own so as adapt to the changing surroundings. After the discovery of antibiotics in 1940, a golden era started that influenced the world by reducing illness as well as mortality. Antibiotics are used to prevent and treat infectious diseases caused by bacteria. Profitable enterprise in rearing food-producing animals depends upon high productivity. Use of antibiotics as growth promoters in food producing animals is a trend to achieve maximum growth within short period of time. The rampant use of antibiotics, either for therapeutics or for enhancing production in food producing animals has led to the development of antibiotic resistance among various species of bacteria [7].
