Kluyveromyces marxianus is one of the most commonly used alternative yeasts which an efficient transformation system was developed. It has a usage in food fermentation, and it is categorized as “Generally Regarded As Safe (GRAS)” which makes it a good candidate for food and pharmaceutical applications. K. marxianus can grow on relatively cheap lactose based media and ferments xylose to ethanol, and its is considered as zero explosion risk which most of the methylotrophic yeast is not. This allows cost reduction by not requiring explosion-proof plants. Ethanol production represents main selling point of K. marxianus utilization. In the fermentation of renewable biomass residues, its capability to simultaneously consume glucose and xylose makes it a desirable choice for maximizing ethanol production.