Utilisation of cheese whey as an alternative growth medium for recombinantstrains of Kluyveromyces marxianus

Kluyveromyces marxianus KMDB-1, a plasmid-bearing recombinant, not carrying any particular gene of relevance, derived from auxotrophic strain KMS-2 (u ra(-)), grew in cheese whey with a maximum specific growth rate of 0.34 h(- 1). This recombinant strain showed the same lactose uptake and extracellula r protease production kinetics as the wild type CBS6556 with no evidence of catabolite repression. The plasmid was retained in 50% of cells after 36 h of batch culture. The presence of this vector in Kluyveromyces marxianus, which possesses no natural plasmids, together with the absence of any metab olic loading effect, creates a suitable microbial system for cheese whey pr ocessing for potential value-added product formation.