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AMB Express. 2012; 2: 38.
Published online Jul 29, 2012. doi:  10.1186/2191-0855-2-38
PMCID: PMC3431993
A novel Kluyveromyces marxianus strain with an inducible flocculation phenotype
Juan A Vallejo,#1 Manuel Serrat,#2 Irasema Pérez-Portuondo,2 Angeles Sánchez-Pérez,3 Jose M Ageitos,1 and Tomas G Villacorresponding author1
1Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Santiago de Compostela, Campus Sur 15782, 15706, Santiago de Compostela, Spain
2Industrial Biotechnology Studies Center (CEBI), University of Oriente, Ave. Patricio Lumumba s/n, 90500, Santiago de Cuba, Cuba
3Discipline of Physiology and Bosch Institute, School of Medical Sciences, University of Sydney, Sydney, NSW, 2006, Australia
corresponding authorCorresponding author.
#Contributed equally.
Juan A Vallejo: juanvallejo/at/gmail.com; Manuel Serrat: mserrat/at/cebi.uo.edu.cu; Irasema Pérez-Portuondo: iperez/at/cebi.uo.edu.cu; Angeles Sánchez-Pérez: angeles.sanchez-perez/at/sydney.edu.au; Jose M Ageitos: josemanuel.ageitos/at/gmail.com; Tomas G Villa: tom.villa/at/gmail.com
Received July 11, 2012; Accepted July 20, 2012.
Abstract
Flocculation is a very useful phenotype for industrial yeast strains, since it facilitates cell harvest and represents an easy way of cell immobilization in continuous fermentation processes. The present work represents the first time that an inducible flocculation phenotype has been generated in a non flocculent strain of Kluyveromyces marxianus. This was accomplished by expressing Saccharomyces cerevisiae FLO5 gene in K. marxianus CECT 11769 strain. The FLO 5 gene was placed under the control of an EPG promoter, not repressed by glucose and induced by anoxia. Our experimental approach successfully generated two novel K. marxianus flocculent phenotypes: one inducible and one constitutive. The constitutive phenotype originated from deletions in the FLO5 promoter region, indicating the existence of putative upstream repressor site involved in oxygen regulation of the EPG1 promoter. The novel strains here generated had a unique set of characteristics that provided an advantage, over the wild-type strain, for the industrial co-production of ethanol and polygalacturonase.
Keywords: Kluyveromyces marxianus, Inducible flocculent phenotype, Polygalacturonase, Ethanol
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