Preface The book is primarily meant for students appearing for competitive examinations such as ARS-NET, ICAR-JRF, ICAR-SRF, GATE and viva voce in Agricultural Microbiology and Microbiology. Agricultural Microbiology is one of the important components of the syllabus in ARS-NET, ICAR-JRF, ICAR-SRF exams. The main aim of this book is to help students to review their knowledge of Agricultural Microbiology acquired through textbooks and to understand the subject with logical reasoning. Microbiology is the study of microorganisms that cannot be seen with the naked eye. These include bacteria, viruses, fungi, prions, archaea, protozoa and algae which are collectively known as ‘microbes’. These microbes play significant roles in biogeochemical cycle, nutrient cycling, biomass decomposition, biodegradation/bio deterioration, food fermentation, food spoilage, and in Sewage treatment, Agriculture and Pharmaceuticals. There are lots of industrial applications of micro-organisms and their activities are vitally significant for various processes. The book will be published in two volumes, this is the first volume that has seven chapters: chuapter 1- agriculture microbiology, chapter 2- microbiology of water, chapter 3-food microbiology, chapter 4-industrial microbiology, chapter- 5-general microbiology, chapter-6- microbial growth and groth control and chapter 7-microbial physiology. In this book I have tried to give complete and latest information on various aspects of microbiology in objectives form with their proper answer. I am very much grateful to New India Publishing Agency for publishing this book. I am very much hopeful that this book will be very much used by students of Agricultural Microbiology, General Microbiology, Biotechnology.