National Education Policy (NEP-2020) emphasizes a holistic, flexible and multidisciplinary approach in higher education with a focus on conceptual understanding, critical thinking and skill development. In alignment with this vision and as per the revised syllabus prescribed by KBC NMU, Jalgaon, the subject MB-215: Microbiology of Air, Water and Soil has been designed for S.Y.B.Sc. Microbiology students to provide a strong foundation in the Industrial Microbiology.Industrial Microbiology is branch of microbiology; it explores the basics of fermentation process. This provides the structure of fermenter, its types and fermentation process. The study of microorganisms involved in fermentation further extends the understanding of primary screening and secondary screening. It also focused on the upstream and downstream processes.This book has been written in a student-friendly manner to meet the requirements of the revised curriculum. Each unit is structured systematically with clear explanations, illustrative examples, diagrams and end-of-unit exercises to reinforce learning outcomes. The authors express their sincere gratitude to the academic fraternity, colleagues and institutions for their encouragement and guidance. We also acknowledge the support of the publisher, M/s Prashant Publications, Jalgaon, for their cooperation in bringing out this edition in time and in an elegant format.While utmost care has been taken in preparing the manuscript, the authors sincerely regret any errors or omissions that might have occurred. We wholeheartedly welcome constructive feedback, suggestions and comments from teachers and students, which will be invaluable in improving future editions.