Abstract: Kluyveromyces hosts and DNA expression cassettes for use in Kluyveromyces are provided for transcription of endogenous and/or exogenous DNA, and production of peptides, for enhancing production of an endogenous product, or producing an exogenous product. The Kluyveromyces hosts find particular use for secretion of a desired peptide product, where signal sequences may be native to the peptide or provided from endogenous or exogenous signal sequences, including synthetic sequences, functional in Kluyveromyces. A transformation procedure is provided for efficiently transforming Kluyveromyces.

Abstract: A new cloning system is described capable of expressing genetic material derived from recombinant DNA material, which comprises a yeast of the genus Kluyveromyces as a host. Suitable vectors are e.g. vectors containing autonomously replicating sequences (ARS) and vectors containing homologous Kluyveromyces DNA acting as a site for recombination with the host chromosome. New and preferred vectors are those containing ARS sequences originating from Kluyveromyces (KARS vectors). The genetically engineered new strains of Kluyveromyces produce, inter alia, lactase and chymosin.