This book covers the most recent advances in all the topics with which researchers and professionals need to be familiar in order to obtain a better understanding of, and to better exploit, beneficial plant-microbe interactions. The use of microorganisms for agriculture and environmental applications is gaining importance worldwide to improve crop performance, but also for other environmental applications, such as bioremediation in chemically polluted soils. The search for an equilibrium between fundamental and applied aspects makes this book useful for professionals at various levels in the value chain of the “microbial biofertilizers”. Challenges of comercializing biofertilizers involve efficiency of the products and safety for human health and the environment, topics that have paid central attention in this book. Students, scientists and biofertilizers developers will find updated and comprehensive information about the different aspects to be considered to address a successful introduction of biofertilizers in sustainable agriculture and environmental actions.