sentences:  Two genes, "LAC12" and "LAC4", allow "K. marxianus" to absorb and use lactose as a carbon source.This species is considered to be a "crabtree negative fungus", meaning it is unable to convert sugars into ethanol as effectively as crabtree positive taxa such as "S. cerevisiae".Studies, however, deem it to be crabtree positive which is likely due to strain differences since "K. marxianus" possesses the necessary genes to be crabtree positive.