Genetic characterization of the yeast Pichia anomala (strain K), an antagonist of postharvest diseases of apple

Abstract

Aims:To obtain information about the genomic organization of Pichia anomala (strain K) and about its genomic diversity at species and intraspecies level. Methods and Results: The PFGE karyotype of strain K was composed of four bands ranging in size from 1AE1 to 3AE2 Mb. The number of chromosomes was estimated at six since bands 2 and 3 seemed to result from the comigration of two chromosomes with similar size. A comparison of strain K and Hansenula wingeii migration profiles led to the estimate of K strain genome size at 11AE7 Mb. Comparison with isogenic strains, resulting from the sporulation of strain K, highlighted some major karyotypic differences. Two segregants (KH6 and KH7) showed supernumerary chromosomes and one (KH9) displayed chromosomal length polymorphism. This genomic instability was confirmed by molecular hybridization with four probes, consisting of URA3, LEU2, PAEXG1 and PAEXG2 genes of P. anomala. URA3 and LEU2 probes showed second hybridization signals on supernumerary chromosomes of strain KH7 and on chromosome 6 of strain K for LEU2 only. Karyotypic comparison of seven nonisogenic P. anomala strains revealed chromosomal length polymorphism, a sign of intraspecies variation. Conclusions: This work has supplied information about genome size and chromosome number of strain K of P. anomala. The strain seems to be aneuploid because of the presence of supernumerary chromosomes and additional hybridization signals for URA3 and LEU2 probes in the chromosomal profile of some segregants. The work also highlighted genomic diversity within the P. anomala species. Significance and Impact of the Study: Results obtained here increase information about the aneuploidy of P. anomala (strain K). Information about the genomic diversity of the segregants will be of great interest for further studies on strain K mode of action. The genome size and chromosomal profile of P. anomala presented here are different from the results obtained elsewere for Hansenula anomala, while Hansenula is included as a synonym of Pichia. This warrants further studies to investigate this taxonomic relationship.

Isolation and Biomass Production of a Saccharomyces cerevisiae Strain Binding Copper and Zinc Ions

“…Labeling was done with the Megaprime DNA Labeling System (Amersham Bioscience) and with [α-P 32 ] 2′-deoxycytidine 5′-triphosphate (3,000 Ci/mol, Amersham Bioscience) as recommended by the supplier. The hybridization and prehybridization conditions were as described by Ausubel [20]. A solution of 20× salinesodium citrate (SSC) was prepared (173.3 g/l NaCl and 88.2 g/l Na citrate, adjusted to pH 7.5 and autoclaved before use), and the membranes were washed for 5 min at room temperature with 4× SSC+0.1% sodium dodecyl sulfate (SDS), 2× SSC+0.1% SDS, and 0.5× SSC+0.1% SDS successively and finally for 10 min with 0.2× SSC+0.1% SDS.…”

“…Whole chromosomes of the 19 new strains were extracted and separated by pulsed gel electrophoresis according to Johnston [19] and Friel et al [20]. The CHEF-DRII apparatus (contour clamped homogeneous electric fields) from Bio-Rad was used to separate the yeast chromosomes.…”

Identification of Differentially Expressed Genes by cDNA-Amplified Fragment Length Polymorphism in the Biocontrol Agent Pichia anomala (Strain Kh5)

“…Strain Kh5 is a segregant of P. anomala strain K (21). It displays the same biocontrol properties (unpublished data) and the same chromosomal pattern as strain K (14). Strain Kh5 was grown at 25°C in an Erlenmeyer flask containing 50 ml of a medium consisting of yeast nitrogen base ([YNB] 0.65%, wt/vol) (Becton Dickinson & Co., Sparks, MD) and glucose (0.2%, wt/vol) (Merck, Darmstadt, Germany).…”

Pichia anomala and Candida oleophila in Biocontrol of Postharvest Diseases of Fruits: 20 Years of Fundamental and Practical Research

“…The genome of P. anomala strain K was characterized in order to better understand its organization and to design the most appropriate disrupting strategies (Friel et al 2005). Through Pulse-Field Ge Elecrophoresis (PFGE), the number of chromosomes of strain K was estimated at 6, ranging in size between 1.1 and 3.2 Mb and representing a genome of 11.7 Mb.…”