A device and method for detecting by fluorescence microbial growth from sample substances are disclosed. For example, a method for the detection of visible-band fluorescence signals generated by at least one fluorescing compound excited by ultraviolet energy, comprising exciting said at least one fluorescing compound with ultraviolet energy emitted from a light-emitting diode comprising wavelengths below 400 nanometers, and detecting a visible-band fluorescence signal generated by said at least one excited fluorescing compound with at least one light detector sensitive to electromagnetic energy comprising wavelengths greater than or equal to 400 nanometers wavelength. For example, a device for detecting visible-band fluorescence signals generated by at least one fluorescing compound excited by ultraviolet energy, comprising at least one ultraviolet light-emitting diode generating electromagnetic radiation comprising wavelengths below 400 nanometers and capable of exciting the at least one fluorescing compound, at least one light detector sensitive to electromagnetic energy comprising wavelengths greater than or equal to 400 nanometers wavelength for the detection of visible-band fluorescence signals generated by the at least one fluorescing compound.