In the past 50 years, numerous polypeptide antibiotics have been identified mainly by bacterial production. These polypeptide antibiotics have been shown to have antibacterial activity against many bacteria specially gram positive bacteria. Some of these polypeptide antibiotics could also be used as growth promoter in poultry feed. This book also provides detailed information about production of bacitracin by Bacillus licheniformis. In this regard, systematic approach was adopted. In the first step, different isolates of Bacillus licheniformis were isolated from soil, milk and poultry droppings. Screening of different isolates based on bacitracin production was carried out. Production of bacitracin was then enhanced by using physical and chemical mutagenesis. Then optimization of different parameters was accomplished. In the end partial purification of Zn-bacitracin was carried out. The Zn-bacitracin thus obtained was then tested in poultry as growth promoter and found to be suitable for use in poultry. This book could be helpful for students and teachers in the fields of biology, biotechnology, fermentation and polypeptide antibiotics.