Nucleotide composition of nuclear and mitochondrial deoxyribonucleic acid of fungi

Genome Assembly and Genetic Traits of the Pleuromutilin-Producer Clitopilus passeckerianus DSM1602

The gilled mushroom Clitopilus passeckerianus (Entolomataceae, Agaricales, Basidiomycota) is well known to produce the terpenoid pleuromutilin, which is the biotechnological basis for medically important antibiotics such as lefamulin and retapamulin. Their unique mode of action and good tolerance entails an increasing demand of pleuromutilin-derived antibiotics in veterinary and human health care. Surprisingly, despite their pharmaceutical importance, no genome sequence is available of any pleuromutilin-producing fungus. Here, we present the high-quality draft genome sequence of the pleuromutilin-producer C. passeckerianus DSM1602 including functional genome annotation. More precisely, we employed a hybrid assembly strategy combining Illumina sequencing and Nanopore sequencing to assemble the mitochondrial genome as well as the nuclear genome. In accordance with the dikaryotic state of the fungus, the nuclear genome has a diploid character. Interestingly, the mitochondrial genome appears duplicated. Bioinformatic analysis revealed a versatile secondary metabolism with an emphasis on terpenoid biosynthetic enzymes in C. passeckerianus and also in related strains. Two alleles of biosynthetic gene clusters for pleuromutilin were found in the genome of C. passeckerianus. The pleuromutilin genes were reassembled with yeast-specific elements for heterologous expression in Saccharomyces cerevisiae. Our work lays the foundation for metabolic strain engineering towards higher yields of the valuable compound pleuromutilin.

Comparison of the lignin-degrading white rot fungi Phanerochaete chrysosporium and Sporotrichum pulverulentum at the DNA level

DNA-hybridisation studies showed a close relationship between Phanerochaete chrysosporium ME446, most used in lignin degradation studies, and Sporotrichum pulverulentum Novobranova, the other standard lignin degrading strain. Two other strains of P. chrysosporium were both less related. We show that P. chrysosporium ME446 and S. pulverulentum Novobranova both have a GC-content of 59% for chromosomal DNA with the rRNA genes present as an AT-rich satellite; the mitochondrial DNA has a GC-content of 33%. The genome size estimated for P. chrysosporium ME446 is about 4-5 × 10(7) bp.

Establishment and interpretation of the genome sequence of the phytopathogenic fungus Rhizoctonia solani AG1-IB isolate 7/3/14

Anastomosis group AG1-IB isolates of the anamorphic basidiomycetous fungus Rhizoctonia solani Kühn affect various agricultural and horticultural important crops including bean, rice, soybean, figs, hortensia, cabbage and lettuce. To gain insights into the genome structure and content, the first draft genome sequence of R. solani AG1-IB isolate 7/3/14 was established. Four complete runs on the Genome Sequencer (GS) FLX platform (Roche Applied Science) yielding approx. a 25-fold coverage of the R. solani genome were accomplished. Assembly of the sequence reads by means of the gsAssembler software version 2.6 applying the heterozygotic mode resulted in numerous contigs and scaffolds and a predicted size of 87.1 Mb for the diploid status of the genome. 'Contig-length vs. read-count' analysis revealed that the assembled contigs can be classified into five different groups. Detailed BLAST-analysis revealed that most contigs of group II feature high-scoring matches to other contigs of the same group suggesting that distinguishable allelic variants exist for many genes. Due to the supposed diploid and heterokaryotic nature of R. solani AG1-IB 7/3/14, this result has been anticipated. However, the heterokaryotic character of the isolate is not really supported by sequencing data obtained for the isolate R. solani AG1-IB 7/3/14. Coverage of group III contigs is twice as high as for group II contigs which can also be explained by the diploid status of the genome and indistinguishable alleles on homologous chromosomes. Assembly of sequence data led to the identification of the rRNA unit (group V contigs) and the mitochondrial (mt) genome (group IV contigs) which is a circular molecule of 162,751 bp in size featuring a GC-content of 36.4%. The R. solani 7/3/14 mt-genome is one of the largest fungal mitochondrial genomes known to date. Its large size essentially is due to the presence of numerous non-conserved hypothetical ORFs and introns. Gene prediction for the R. solani AG1-IB 7/3/14 genome was conducted by the Augustus Gene Prediction Software for Eukaryotes (version 2.6.) applying the parameter set for the fungus Coprinopsis cinerea okayama 7#130. Gene prediction and annotation provided first insights into the R. solani AG1-IB 7/3/14 gene structure and content. In total, 12,422 genes were predicted. The average number of exons per gene is five. Exons have a mean length of 214 bp, whereas introns on average are 66 bp in length. Annotation of the genome revealed that 4169 of 12,422 genes could be assigned to KOG functional categories.

The mitochondrial genome of Mucor piriformis

DNA was purified from the isolated mitochondria of a Mucor piriformis wild-type strain (NRRL 26211). A circular restriction map of the mitochondrial DNA was established on the basis of single and double digests with several restriction endonucleases. The average mitochondrial DNA size calculated from these data was 33.53 kbp; this is in good agreement with the contour length size (33.62 kbp) of the open circular molecules detected by electron microscopy. Heterologous hybridizations with cloned Aspergillus nidulans mitochondrial genes were used to locate some coding regions on the map.

A methylated Neurospora 5S rRNA pseudogene contains a transposable element inactivated by repeat-induced point mutation

In an analysis of 22 of the roughly 100 dispersed 5S rRNA genes in Neurospora crassa, a methylated 5S rRNA pseudogene, Psi63, was identified. We characterized the Psi63 region to better understand the control and function of DNA methylation. The 120-bp 5S rRNA-like region of Psi63 is interrupted by a 1.9-kb insertion that has characteristics of sequences that have been modified by repeat-induced point mutation (RIP). We found sequences related to this insertion in wild-type strains of N. crassa and other Neurospora species. Most showed evidence of RIP; but one, isolated from the N. crassa host of Psi63, showed no evidence of RIP. A deletion from near the center of this sequence apparently rendered it incapable of participating in RIP with the related full-length copies. The Psi63 insertion and the related sequences have features of transposons and are related to the Fot1 class of fungal transposable elements. Apparently Psi63 was generated by insertion of a previously unrecognized Neurospora transposable element into a 5S rRNA gene, followed by RIP. We name the resulting inactivated Neurospora transposon PuntRIP1 and the related sequence showing no evidence of RIP, but harboring a deletion that presumably rendered it defective for transposition, dPunt.

Regulation of the expression of three housekeeping genes encoding subunits of the Neurospora crassa vacuolar ATPase

The vacuolar ATPase is a complex enzyme and is encoded by at least nine genes, which appear to be scattered throughout the genome. We have examined the vma-1 vma-2, and vma-3 genes, which encode subunits present in multiple copies within the Neurospora crassa vacuolar ATPase. We wished to see if the expression of these genes is coordinately regulated and if these genes contain similar promoter elements. A region was sequenced of approximately 1 kb located upstream of the protein coding region for each gene. Several sequence elements were found in similar positions in each of the three genes. Each of the genes had several strong transcription initiation sites, clustered within 13-60 bp and located 112-193 bp upstream of the translation start site. The size and abundance of the RNA transcripts was also determined: the amount of RNA transcribed from each gene was roughly proportional to the numbers of each subunit present in the enzyme. A series of plasmids was constructed containing parts of the putative promoter region fused to beta-galactosidase. Analysis of these plasmids indicated that the essential region of the vma promoters lies within 370 bp of the protein coding region. Overall, the vma genes appear to have similar characteristics to "housekeeping" genes described in other organisms.

Mitochondrial genome of the dimorphic zygomycete Mucor racemosus

Mitochondria were isolated from the dimorphic zygomycete Mucor racemosus by differential centrifugation. DNA from the organelles was purified by cesium chloride-ethidium bromide isopycnic centrifugation. Examination of the mitochondrial DNA by electron microscopy revealed a circular chromosome approximately 63.8 kbp in circumference. The chromosome was digested with restriction endonucleases and the resulting DNA fragments were separated by agarose-gel electrophoresis. Electophoretic mobilities and stoichiometry of the fragments indicated a mixed population of mtDNA molecules each with a size of about 63.4 kbp. Physical maps were constructed from analyses of fragments generated in single and double restriction digests and from the hybridization of fragments to probes for the large and small mitochondrial rRNA genes from Saccharomyces cerevisiae. The Mucor mitochondrial chromosome was found to exist in the form of two flip-flop isomers with inverted repeat sequences encoding both rRNA genes.

The Ncypt1 gene from Neurospora crassa is located on chromosome 2: molecular cloning and structural analysis

Small GTP-binding proteins are encoded by ras-like genes and play a central role in cell differentiation and membrane vesicle transport. By screening genomic and cDNA libraries of the Ascomycete fungus Neurospora crassa with Zmypt genes from Zea mays we have isolated a member of the ypt gene family, Ncypt1. The gene resides on a 4 kb fragment of genomic DNA and contains four introns, which interrupt the coding sequence of a protein of 203 amino acid residues. The Ncytp1 gene was assigned to a single-copy gene encoding a transcript of 1.5 kb and a protein of 26,000 daltons. The gene maps on linkage group IIR between DB0001 and ccg-2 close to the Fsr-3 locus. Analysis of the nucleotide sequence and the deduced protein sequence revealed a striking homology to yeast, mouse and human genes encoding small GTP-binding proteins that are related to the ras supergene family. Homology was most significant to ypt1 from Schizosaccharomyces pombe, Mus musculus and Homo sapiens sharing 84.8%, 82.3%, and 82.3% identity, respectively. Common domains present in other small GTP-binding proteins were identified in the predicted sequence of the NCYPT1 protein, and the arrangement of peptide motifs sharing similarity with well characterized, small GTP-binding proteins suggests that the NCYPT1 protein is a GTPase. The C-terminal region extending from amino acid residues 175 to 199 shares only weak amino acid sequence similarity with other eukaryotic GTPases. Like other RAS proteins the NCYPT1 protein contains two conserved C-terminal cysteine residues, suggesting post-translational modification(s) by fatty acylation required for membrane anchoring. The high degree of homology between the NCYPT1 protein and eukaryotic YPT proteins suggests that NCYPT1 could be involved in the control of secretory processes.

Neurospora crassa blue-light-inducible gene bli-7 encodes a short hydrophobic protein

Blue light induces a number of physiological reactions in Neurospora crassa. We have cloned and sequenced the gene bli-7, which is inducible by blue light, and both glucose and nitrogen starvation. This gene is strongly expressed at the RNA-level and contributes up to 0.2% of N. crassa total RNA when fully induced. The deduced amino acid sequence reveals a short (108 amino acids), hydrophobic protein which has homology to the protein SC-3, encoded by a gene of Schizophyllum commune which was isolated as a gene abundantly expressed at the time of fruiting. The amino-terminus of BLI-7 protein shows resemblance to a number of transit peptides. The comparison of the nucleotide sequence of the promoter region with various N. crassa promoters reveals a striking similarity to the promoter of grg-1, a glucose repressible gene.

Genes expressed during conidiation in Neurospora crassa: molecular characterization of con-13

Asexual development in Neurospora crassa proceeds through a series of discrete morphological stages that culminate in the production of dormant spores called conidia. Changes in the pattern of gene expression parallel the morphological transformations associated with conidiation. As a prerequisite to the analysis of developmental gene expression in N. crassa, several genes of unknown function that are preferentially expressed during conidiation were isolated [Berlin and Yanofsky, Mol. Cell. Biol. 5 (1985) 849-855]. The molecular structure and nucleotide sequence of one of these genes, designated con-13, is presented. The con-13 gene specifies a relatively rare 1.35-kb message which is first detected about 8 h following the induction of conidiation. Sequence analysis of both cDNA and genomic clones indicates that the con-13 gene consists of three exons divided by two small introns. It encodes a polypeptide of 340 amino acid residues (37.1 kDa). The Con-13 protein is weakly acidic and hydrophilic. A comparison of the regions upstream from the con-8, con-10, and con-13 genes revealed several short sequence motifs which may be important in developmental gene regulation.

Primary and secondary structure of the 25S rRNA from the dimorphic fungus Mucor racemosus

A 9.76 Kb ribosomal DNA repeat unit from the nuclear genome of the dimorphic fungus Mucor racemosus (Zygomycetes) was identified using a hybridization probe from the yeast Saccharomyces cerevisiae (Ascomycetes). This material was cloned in Escherichia coli plasmids as four overlapping pieces and mapped with respect to cleavage sites for 12 restriction endonucleases. The nucleotide sequence of the complete 25S rRNA gene and flanking regions was determined. The 5' and 3' ends of the structural gene were identified by comparison with the published sequence for the S. cerevisiae gene. The Mucor gene was found to possess 3469 bp and have a GC content of 42.8%. It was compared with the homologous gene from several other eukaryotes and found to be most similar to that from Saccharomyces. A potential secondary structure of the putative RNA transcript consistent with the structures proposed for the E. coli and Saccharomyces molecules was constructed by computer modelling.

DNA sequence, organization and regulation of the qa gene cluster of Neurospora crassa

In Neurospora, five structural and two regulatory genes mediate the initial events in quinate/shikimate metabolism as a carbon source. These genes are clustered in an 18 x 10(3) base-pair region as a contiguous array. The qa genes are induced by quinic acid and are coordinately controlled at the transcriptional level by the positive and negative regulators, qa-1F and qa-1S, respectively. The DNA sequence of the entire qa gene cluster has been determined and transcripts for each gene have been mapped. The qa genes are transcribed in divergent pairs and two types of transcripts are associated with each gene: basal level transcripts that initiate mainly from upstream regions and are independent of qa regulatory gene control, and inducible transcripts that initiate downstream from basal transcripts and are dependent on qa-1F binding to a 16 base-pair sequence. We discuss how both types of transcription relate to the organization of the qa genes as a cluster and how this may impose constraints on gene dispersal.

Genes expressed during conidiation in Neurospora crassa: characterization of con-8

The filamentous fungus Neurospora crassa, by a series of defined changes, differentiates from a mycelium composed of branching hyphae to form dormant spores, called conidia. Several genes of unknown function (con genes) that are preferentially expressed during this period have been cloned. Transcription of these genes has been examined in conidiation-defective mutants, and the results obtained revealed that con-6, con-8, con-10, con-11 and con-13 are most likely to play a unique role during conidiation, con-8 is expressed early during conidial differentiation. Genomic and cDNA sequence analyses with con-8 clones identified one open reading frame, interrupted by two introns, which encodes a weakly acidic 18.4 kDa polypeptide containing 176 amino acid residues, con-8 is unusual in that it is transcribed as two mRNA species, 1.0 and 1.25 kb in length. S1 nuclease mapping and primer extension analyses identify one major initiation site, one major polyadenylation site, and demonstrated the existence of heterogeneity at the messenger's 5' and 3' ends.

Molecular analysis of a Neurospora crassa gene expressed during conidiation

The asexual developmental pathway in the life cycle of the filamentous fungus Neurospora crassa culminates in the formation of spores called conidia. Several clones of genomic Neurospora DNA have been isolated that correspond to mRNA species expressed during conidiation and not during mycelial growth (V. Berlin and C. Yanofsky, Mol. Cell. Biol. 5:849-855, 1985). In this paper we describe the characterization of one of these clones, named pCon-10a. This clone contains two genes, con-10 and con-13, which are induced coordinately during the later stages of conidiation. The two genes are separated by 1.4 kilobases of DNA; they are located on linkage group IV and are transcribed from the same strand of DNA. The molecular organization and sequence of one of these genes, con-10, and its flanking regions are presented. Full-length cDNA clones for con-10 also were isolated and sequenced, and transcription-initiation and polyadenylation sites were defined. The con-10 gene contains an open reading frame interrupted by two small introns and encodes an 86-amino-acid residue polypeptide that is both hydrophilic and weakly acidic. Expression of the con-10 gene in various mutants defective at different stages of conidiation indicates that it plays a role after aerial hyphal development. Possible functions, organization, and regulation of conidiation-specific genes are discussed.

Molecular analysis of a Neurospora crassa gene expressed during conidiation

The asexual developmental pathway in the life cycle of the filamentous fungus Neurospora crassa culminates in the formation of spores called conidia. Several clones of genomic Neurospora DNA have been isolated that correspond to mRNA species expressed during conidiation and not during mycelial growth (V. Berlin and C. Yanofsky, Mol. Cell. Biol. 5:849-855, 1985). In this paper we describe the characterization of one of these clones, named pCon-10a. This clone contains two genes, con-10 and con-13, which are induced coordinately during the later stages of conidiation. The two genes are separated by 1.4 kilobases of DNA; they are located on linkage group IV and are transcribed from the same strand of DNA. The molecular organization and sequence of one of these genes, con-10, and its flanking regions are presented. Full-length cDNA clones for con-10 also were isolated and sequenced, and transcription-initiation and polyadenylation sites were defined. The con-10 gene contains an open reading frame interrupted by two small introns and encodes an 86-amino-acid residue polypeptide that is both hydrophilic and weakly acidic. Expression of the con-10 gene in various mutants defective at different stages of conidiation indicates that it plays a role after aerial hyphal development. Possible functions, organization, and regulation of conidiation-specific genes are discussed.

Cloning and characterization of the gene for beta-tubulin from a benomyl-resistant mutant of Neurospora crassa and its use as a dominant selectable marker

We cloned the beta-tubulin gene of Neurospora crassa from a benomyl-resistant strain and determined its nucleotide sequence. The gene encodes a 447-residue protein which shows strong homology to other beta-tubulins. The coding region is interrupted by six introns, five of which are within the region coding for the first 54 amino acids of the protein. Intron position comparisons between the N. crassa gene and other fungal beta-tubulin genes reveal considerable positional conservation. The mutation responsible for benomyl resistance was determined; it caused a phenylalanine-to-tyrosine change at position 167. Codon usage in the beta-tubulin gene is biased, as has been observed for other abundantly expressed N. crassa genes such as am and the H3 and H4 histone genes. This bias results in pyrimidines in the third positions of 96% of the codons in codon families in which there is a choice between purines and pyrimidines in this position. Bias is also evident by the absence of 19 of the 61 sense codons. We demonstrated that benomyl resistance is due to the cloned beta-tubulin gene of strain Bml511(r)a and that this gene can be used as a dominant selectable marker in N. crassa transformation.

Cloning and characterization of the gene for beta-tubulin from a benomyl-resistant mutant of Neurospora crassa and its use as a dominant selectable marker

We cloned the beta-tubulin gene of Neurospora crassa from a benomyl-resistant strain and determined its nucleotide sequence. The gene encodes a 447-residue protein which shows strong homology to other beta-tubulins. The coding region is interrupted by six introns, five of which are within the region coding for the first 54 amino acids of the protein. Intron position comparisons between the N. crassa gene and other fungal beta-tubulin genes reveal considerable positional conservation. The mutation responsible for benomyl resistance was determined; it caused a phenylalanine-to-tyrosine change at position 167. Codon usage in the beta-tubulin gene is biased, as has been observed for other abundantly expressed N. crassa genes such as am and the H3 and H4 histone genes. This bias results in pyrimidines in the third positions of 96% of the codons in codon families in which there is a choice between purines and pyrimidines in this position. Bias is also evident by the absence of 19 of the 61 sense codons. We demonstrated that benomyl resistance is due to the cloned beta-tubulin gene of strain Bml511(r)a and that this gene can be used as a dominant selectable marker in N. crassa transformation.

Gene organization and regulation in the qa (quinic acid) gene cluster of Neurospora crassa

Images

Cloning and characterization of the multifunctional his-3 gene of Neurospora crassa

We have cloned the his-3 gene of Neurospora crassa and determined its nucleotide sequence. The gene specifies a protein of 863 amino acids (aa) and contains a 59-bp intron which interrupts aa 800, a proline residue. The 5' end of the his-3 transcript is heterogeneous with major starts 122 and 124 bp upstream from the start codon. There are three possible polyadenylation sites, 119, 120 and 121 bp after the UAA stop codon. The protein shows two regions of homology to the yeast HIS4 gene which correspond to the hisIE and hisD genes of Escherichia coli and Salmonella typhimurium. Northern analysis shows that the level of his-3 mRNA increases severalfold in cultures subjected to histidine starvation.

Characterization of the genome of the basidiomycete Schizophyllum commune

DNA of Schizophyllum commune was isolated both from mycelial cells and from protoplasts. Nuclear DNA was isolated after solubilization of the mitochondria with the detergent Nonidet. The G + C content of the nuclear DNA was 57%, calculated from its buoyant density (1.7165 g/ml) and from the Tm (77.4 degrees C in 15 mM NaCl/1.5 mM trisodium citrate). The buoyant density of the ribosomal cistrons was 1.707 g/ml. DNA isolated from purified mitochondria had a very low G + C content: 22% (rho = 1.6845 g/ml, Tm = 61.8 degrees C in 15 mM NaCl/1.5 mM trisodium citrate). Analysis of CsCl profiles and melting patterns suggested that mitochondrial DNA contains interspersed (A + T)-rich sequences. From reassociation analysis of sheared nuclear DNA the genome size of S. commune was determined to be 22.8 . 10(9) daltons. A small amount of DNA (0.5 . 10(9) daltons) bound to hydroxyapatite at zero time Cot. 7% of the genome (1.6 . 10(9) daltons) represented repetitive DNA.

Characterization of the genome of Phycomyces blakesleeanus

DNA of Phycomyces blakesleeanus was extracted from whole mycelia and from nuclear and mitochondrial organelle fractions obtained from sporangiophores. DNA from all three sources exhibits one symmetrical band at p equals 1.688 g/ml in CsCl buoyant density gradients. Reassociation data are consistent with kinetic division of the DNA into three components: very rapidly renaturing (fraction I), rapidly reassociating (fraction II) and slowly reassociating (fraction III) base sequences. These components comprise approximately 10%, 20% and 64% of total cell DNA. Kinetic fractions were prepared from total cell DNA and reassociated separately. The corrected rate constant is 11.3 M-1-S-1 for the rapidly reassociating component and 0.055 M-1-S-1 for the slowly reassociating component. Based on these data and the data from unfractionated total cell DNA, the genome size of Phycomyces is approximately 1.9-10-10 daltons, 6.7 times that of Escherichia coli.

Deoxyribonucleic acid base composition of the yeastlike and mycelial phases of Histoplasma capsulatum and Blastomyces dermatitidis

The base composition in moles percent guanine plus cytosine (%GC) of both nuclear and mitochondrial deoxyribonucleic acid (DNA) isolated from the yeastlike and mycelial phases of the dimorphic fungal pathogens Histoplasma capsulatum and Blastomyces dermatitidis was determined by techniques of thermal denaturation and CsCl buoyant density gradient equilibrium centrifugation. The mean observed values for GC content of nuclear DNA from H. capsulatum and B. dermatitidis were 47.3 and 48.2%, respectively. What is speculated to be mitochondrial DNA was found to be 34.0% for H. capsulatum and 34.3% for B. dermatitidis. Thermal denaturation curves for Blastomyces DNA indicated a bimodality in thermal denaturation profiles, thereby suggesting a significant mitochondrial DNA contamination. Mitochondrial DNA appeared to represent a smaller percentage of the total DNA prepared from Histoplasma, and was not observed consistently to affect%GC values as determined by thermal denaturation profiles. On the basis of the now known perfect stage of B. dermatitidis (Ajellomyces dermatitidis) as a member of the family Gymnoascaceae, the close approximation of%GC content of nuclear DNA of this fungal organism with that of H. capsulatum suggests possible phylogenetic relationship. It is suggested that the just reported, but as yet unclassified, perfect stage of H. capsulatum may be found to be phylogenetically a primitive form of the Gymnoascaceae.

Nucleotide composition of deoxyribonucleic acid of some species of Cryptococcus, Rhodotorula, and Sporobolomyces

The buoyant density of deoxyribonucleic acid (DNA) from nine species and two varieties of Cryptococcus, three species and two varieties of Rhodotorula, and six species of Sporobolomyces was determined by CsCl density gradient equilibrium centrifugation. Several species were represented by two to four different strains. Expressed in moles per cent of guanine plus cytosine (GC content) the ranges were 49 to 65%, 52 to 70%, and 51 to 65% for Cryptococcus, Rhodotorula, and Sporobolomyces, respectively. For each genus, the GC content was distributed into two discrete groups with averages ranging from 52 to 54 and 60 to 66, respectively. An analysis of these results suggested that the determination of GC content of DNA had a taxonomic value for these yeast genera.

Deoxyribonucleic acid base composition in yeasts

The deoxyribonucleic acid base composition of 15 species of yeasts was determined to obtain further clues to or supporting evidence for their taxonomic position. Species examined belonged to the genera Saccharomyces, Debaryomyces, Lodderomyces, Metschnikowia, and Candida. The range of moles per cent guanine plus cytosine (GC content) for all yeasts examined extended from 34.9 to 48.3%. The sporogenous species and the asporogenous yeasts spanned the range with 36.6 to 48.3% GC and 34.9 to 48% GC, respectively. Three Saccharomyces species (S. rosei and related species) exhibited significantly higher GC contents than S. cerevisiae, whereas the fermentative species D. globosus revealed a%GC more aligned to the S. rosei group than to the nonfermentative D. hansenii. Similar GC contents were demonstrated by L. elongasporus and its proposed imperfect form C. parapsilosis. The range of GC contents of various strains of three Metschnikowia species studied was 6.1%, with the type strain of M. pulcherrima having the highest GC content (48.3%) of all of the yeasts examined.