This book will focus on microbial services as an excellent strategy to face the current challenge of global agriculture, collecting the principal studies that used microbial services for improving cereal production, such as rice, beans, maize and wheat. This book will address studies and discussion about the bacterial world inside the plant; phytostimulator microorganisms; promotion of maize growth for biocontrol; filamentous fungi as plant growth promoters; mycorrhiza; sustainable agriculture effects on the microbiome; humic substances in combination with plant growth-promoting bacteria in rice; and the changes in plant metabolome induced by microorganisms under environmental stress.