Leuconostoc is a genus of gram-positive bacteria, placed within the family of Leuconostocaceae, order Lactobacillales. They are generally ovoid cocci often forming chains. Leuconostoc spp. are intrinsically resistant to vancomycin and are catalase-negative. All species within this genus are heterofermentative and are able to produce dextran from sucrose. They are generally slime-forming. The name Leuconostoc comes from Greek adjective leukos meaning clear; and the word nostoc gelatinous colonies, Leuconostoc - colorless nostoc.