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J Ind Microbiol Biotechnol (2009) 36:14351438 DOI 10.1007/s10295-009-0638-4
SHORT COMMUNICATION
Biotechnological strains of Komagataella (Pichia) pastoris are Komagataella phaYi as determined from multigene sequence analysis
Cletus Paul Kurtzman
Received: 1 July 2009 / Accepted: 28 August 2009 / Published online: 17 September 2009 Society for Industrial Microbiology 2009
Abstract Pichia pastoris was reassigned earlier to the genus Komagataella following phylogenetic analysis of gene sequences. Since that time, two additional species of Komagataella have been described, K. pseudopastoris and K. phaYi. Because these three species are unlikely to be resolved from the standard fermentation and growth tests used in yeast taxonomy, the identity of biotechnologically important strains of K. pastoris was determined from multi-gene sequence analyses. Results from this study show that the strain of Pichia pastoris commonly used in gene expression studies is actually K. phaYi.
Keywords Pichia pastoris Komagataella phaYi
Methanol yeasts Gene expression system
Introduction
Komagataella (Pichia) pastoris has many biotechnological applications. Initially, K. pastoris was developed as a source of single-cell protein because the species can grow on either glucose or methanol, and high cell densities can be maintained under fermentation conditions [11]. Later, a gene expression system was developed to produce large quantities of medically and industrially important proteins [1, 2]. Consequently, two aspects of the species have contributed to its utility: (1) fermentation techniques were developed for maintaining extremely high cell densities in excess of 100 g/l dry weight, and (2) because K. pastoris
assimilates methanol, the expression system is linked with alcohol oxidase, which is abundantly produced in the presence of methanol. The importance of this gene expression system is emphasized by its commercialization by the Invitrogen Corporation (Carlsbad, CA, USA) as the Pichia pastoris Expression Kit, which is widely used in molecular biology studies to express foreign genes [2].
Gene sequence analysis has shown that the genus Pichia is not monophyletic despite the phenotypic similarity of most species. The methanol-assimilating species P. pastoris and Pichia angusta, an obligate synonym of Hansenula polymorpha, were found to be distantly related to one another and to Pichia membranifaciens, the type species of the genus Pichia. Yamada et al. [12, 13] proposed the transfer of P. pastoris to the newly described genus Komagata-ella, and the transfer of P. angusta as Ogataea polymorpha...