This book investigates the pivotal role of microorganisms in elemental cycling and degradation processes, offering a comprehensive exploration of their chemical reactivity and metabolic diversity. By examining the interaction of microorganisms with geological activities, this volume highlights their influence on biotransformation and bioremediation. Readers will find an in-depth review of geo-microbes applications in soil improvement and environmental restoration, alongside discussions on bio-sediment, bioleaching, and elemental cycling. The chapters offer expert analysis and diverse perspectives in microbiology, geology, and environmental biotechnology. Key concepts include the geomicrobiological interactions in extreme environments, the transformation of toxic elements, and the potential for extraterrestrial life models. Chapters delve into the rehabilitation of saturated lands, the role of geo-microbes in arsenic transformation, and the ecological restoration of wetlands. The book is invaluable for researchers, students, and professionals in microbiology, biotechnology, geology, and environmental sciences. It also serves as a major reference for understanding the microbial processes that shape our planet and offers practical insights for harnessing the power of geo-microbes for sustainable environmental solutions. While comprehensively reviewing geo-microbes in biotransformation processes, the book provides the knowledge and tools necessary to advance the readers’ understanding of geomicrobiology and its applications.