Unit Commitment (UC) is an optimization problem used to find out the least cost dispatch of obtainable generation resources to meet up an expected electric power demand over a certain time perspective under generational, technical and ecological constraints. In the midst of the momentous increase of non-conventional energy sources incorporation into the power system networks, effects caused by these system alterations to the UC are dynamically being studied and examined by worldwide researchers. This paper presents a literature review of application of several optimization algorithms to elucidate the UC problem in microgrids. Lastly a few basic challenges arising from the new optimization approaches in microgrids are addressed.