Phytases are a group of enzymes capable of releasing phosphate from phytate, one of the most abundant forms of organic phosphate in the natural environment. Phytases can be found in many organisms; in bacteria, they are particularly described in g-proteobacteria. In recent years, bacterial phytases have been isolated, characterized and proposed as potential tools in biotechnology. Microbial phytases have been applied mainly to animal (swine and poultry) and human foodstuffs in order to improve mineral bioavailability and food processing. Here, we summarize the current knowledge of bacterial phytases and phytase-producing bacteria, as well as their potential biotechnological applications, including new fields poorly explored, such as fish nutrition, environmental protection and plant nutrition. Despite the recognized importance in biotechnology, information on bacterial phytases and phytase-producing bacteria is clearly limited and major efforts are required to improve the knowledge of phytases present in bacteria and their utilization.