Microbial biosensors for environmental monitoring Microbial biosensors are analytical devices capable of sensing substances in the environment due to the specific bio-logical reaction of the microorganism or its parts. Construc-tion of a microbial biosensor requires knowledge of microbial response to the specific analyte.Biosensors can be useful for determining the type and concentration of contaminants present in an environment. The primary measurement media for environmental monitoring is water, soil and air, but there are a variety of other target analytes. In the present paper biosensors that can be used for environmental monitoring and alarm systems for specific analytes are summarized. The possible analytes include heavy metals, herbicides, pesticides, phenolic compounds, etc. In the recent years the potential harmful pollutants into the environment are increasing. So, we have to look for more rapid and more efficient methods for observation. In order to monitor the environ-mint continuously, it is necessary to build monitor-in systems. This requires the development of new technologies and appropriate methodologies in the field. In this context, the biosensors appear as suitable candidates. Biosensors for environmental monitoring, represent analytical devices which use for a sensing element biomaterial, chemical element or a combination of both