The effects of radiation on antitumor efficacy of an oncolytic adenovirus vector in the Syrian hamster model

We report that radiation enhances the antitumor efficacy of the oncolytic adenovirus vector VRX-007 in Syrian hamster tumors. We used tumor-specific irradiation of subcutaneous tumors and compared treatment options of radiation alone or combined with VRX-007 and cyclophosphamide (CP). Radiation therapy further augmented the VRX-007-mediated inhibition of tumor growth, in both CP-treated and non-CP-treated hamsters, even though radiation did not lead to increased viral replication in tumors when compared to those treated with VRX-007 alone. Moreover, tumor growth inhibition was similar in tumors irradiated either one week before or after injection with VRX-007, which suggests that radiation exerts its antitumor effect independently from vector therapy. Thus, our results demonstrate that these two therapies do not have to be provided simultaneously to enhance their combined effectiveness against subcutaneous hamster tumors.

A fully replication-competent adenovirus vector with enhanced oncolytic properties

We have studied the oncolytic efficacy of two adenovirus vectors named KD3 and INGN 007, which differ from each other only in that whereas KD3 has two small deletions in its e1a gene that restrict its replication to rapidly cycling cells, INGN 007 has wild-type e1a gene. Both vectors overexpress the adenovirus death protein (ADP). Both KD3 and INGN 007 effectively suppressed the growth of subcutaneous human A549 and Hep3B tumors in nude mice upon intratumoral injection, and contained the growth of subcutaneous LNCaP tumors after intravenous injection, making some tumors shrink or disappear. However, in a more demanding model, intravenous injections of neither KD3 nor wild-type Ad5 were effective against subcutaneous A549 tumors, whereas INGN 007 increased the mean survival time by 35%. INGN 007 was also effective in suppressing tumor growth in a challenging A549 orthotopic lung cancer model. INGN 007 was superior to dl1520 (ONYX-015) in repressing subcutaneous A549 tumors. Our results suggest that vectors such as INGN 007 might provide better antitumor efficacy in the clinic as well.

New pancreatic carcinoma model for studying oncolytic adenoviruses in the permissive Syrian hamster

Syrian hamster is a practical animal model for studying the systemic effects of oncolytic vectors derived from adenovirus serotype 5 (Ad5). Ad5 replicates well in Syrian hamster tissues, and Syrian hamster cell lines are available that are known to support Ad5 replication. In this study, we established four new Syrian hamster cell lines from transplantable pancreatic, renal, hepatic and lung tumors. The pancreatic cell line (SHPC6) and the renal cell line were highly permissive for Ad5 replication. The SHPC6 cell line formed disseminated intraperitoneal tumors when cells were injected into the peritoneal cavity. INGN 007, an oncolytic Ad5-based vector, completely reversed the growth of disseminated intraperitoneal SHPC6 tumor nodules following intraperitoneal injection of the vector, leading to 100% survival of the treated animals. SHPC6 cells also formed subcutaneous tumors, whose growth was suppressed by INGN 007 following intratumoral injection. INGN 007 replicated in both the intraperitoneal and subcutaneous SHPC6 tumors. Following intraperitoneal injection, INGN 007 did not replicate in the livers of hamsters with intraperitoneal SHPC6 tumors, and was not hepatotoxic. These studies suggest that the SHPC6 cell line may be useful as a model for disseminated pancreatic cancer, and that INGN 007 may be a safe and effective vector to treat these tumors.

INGN 007, an oncolytic adenovirus vector, replicates in Syrian hamsters but not mice: comparison of biodistribution studies

Preclinical biodistribution studies with INGN 007, an oncolytic adenovirus (Ad) vector, supporting an early stage clinical trial were conducted in Syrian hamsters, which are permissive for Ad replication, and mice, which are a standard model for assessing toxicity and biodistribution of replication-defective (RD) Ad vectors. Vector dissemination and pharmacokinetics following intravenous administration were examined by real-time PCR in nine tissues and blood at five time points spanning 1 year. Select organs were also examined for the presence of infectious vector/virus. INGN 007 (VRX-007), wild-type Ad5 and AdCMVpA (an RD vector) were compared in the hamster model, whereas only INGN 007 was examined in mice. DNA of all vectors was widely disseminated early after injection, but decayed rapidly in most organs. In the hamster model, DNA of INGN 007 and Ad5 was more abundant than that of the RD vector AdCMVpA at early times after injection, but similar levels were seen later. An increased level of INGN 007 and Ad5 DNA but not AdCMVpA DNA in certain organs early after injection, and the presence of infectious INGN 007 and Ad5 in lung and liver samples at early times after injection, strongly suggests that replication of INGN 007 and Ad5 occurred in several Syrian hamster organs. There was no evidence of INGN 007 replication in mice. In addition to providing important information about INGN 007, the results underscore the utility of the Syrian hamster as a permissive immunocompetent model for Ad5 pathogenesis and oncolytic Ad vectors.

Oncolytic adenovirus that overproduces ADP and replicates selectively in tumors due to hTERT promoter-regulated E4 gene expression

We have constructed a novel oncolytic adenovirus (Ad) vector, named VRX-011, in which the replication of the vector is targeted to cancer cells by the replacement of the wild-type Ad E4 promoter with the human telomerase reverse transcriptase (hTERT) promoter. Genes in the Ad E4 transcription unit are essential for Ad replication; therefore, VRX-011 will grow efficiently only in cells in which the hTERT promoter is active, that is, in a wide range of cancer and immortalized cells but not in most somatic cells. Consistent with these expectations, VRX-011 replicated efficiently in all cancer cell lines examined, while its growth was restricted in various primary and normal cells. VRX-011 overexpresses ADP (also known as E3-11.6K), an Ad protein required for efficient cell lysis and release of virions from cells at late stages of infection. This overexpression enhances cell-to-cell spread and could significantly increase antitumor efficacy. In a xenograft model in nude mice, both intratumoral and intravenous administration of VRX-011 effectively suppressed the growth of subcutaneous Hep3B human liver tumors. Also, intravenous delivery of VRX-011 greatly reduced the number and size of A549 human lung cancer cell nodules in a disseminated lung tumor model in nude mice. Importantly, tail vein administration of different doses of VRX-011 in C57BL/6 mice showed minimal liver toxicity. Considering its broad range of lytic replication in cancer cells, its attenuated phenotype in primary cells, its efficacy in suppressing xenografts, and its low toxicity in mouse liver, VRX-011 is a promising candidate for further evaluation as an anticancer therapeutic.

Dynamics of metabolism and its interactions with gene expression during sporulation in Saccharomyces cerevisiae

The dynamics of metabolism has been shown to be involved in the triggering of events that are concurrent with sporulation of the budding yeast Saccharomyces cerevisiae. Indeed, quantitative correlations have been demonstrated between sporulation and the rate of carbon substrate or oxygen consumption, and the fluxes through gluconeogenic and glyoxylate cycle pathways. The results suggest that an imbalance between catabolic and anabolic fluxes influences the occurrence of the differentiation process. The hypothesis that the initiation of sporulation is triggered by the accumulation of an intracellular metabolite is confronted with the notion that intermediary metabolism and the expression of genes involved in sporulation interact to trigger the differentiation process. Several pieces of evidence indicate that derepression of the gluconeogenic pathway is crucial for the initiation of sporulation. One of the possible pathways through which glucose repression hampers sporulation might be the repression of gluconeogenesis as well as that of respiratory activity, in turn modulating the expression of IMEL++. The stages defined in the dynamics of sporulating cultures, namely readiness and commitment, are related to metabolic events associated with sporulation. An interpretation in terms of metabolic flux dynamics is given to the reversal of commitment occurring when the normal progression to sporulation is somehow blocked. The quantitative data are here integrated in a model attempting to simulate the dynamics of metabolic as well as cellular events during sporulation. The model is envisaged as a test of the hypothesis that an imbalance between anabolism and catabolism is involved in initiation of the sporulation process. It is proposed that such an imbalance may be a signal for differential gene expression associated with the differentiation pathway.

Fed-batch and continuous culture ofPhaffia rhodozyma (Xanthophyllomyces dendrorhous)

The basidiomycetous yeastPhaffia rhodozyma was grown in batch, fed-batch and continuous culture, and some parameters governing growth and total carotenoid production were determined.

Modulation of sporulation and metabolic fluxes in Saccharomyces cerevisiae by 2 deoxy glucose

Quantitative studies of metabolic fluxes during Saccharomyces cerevisiae sporulation on acetate in the presence of the glucose analog, 2-deoxy glucose (2dG) are reported. We have studied the inhibition of sporulation and associated catabolic or anabolic fluxes by 2dG. Sporulation frequencies decreased from 50% to 2% asci per cell at 2dG concentrations in the range of 0.03 to 0.30 g l-1, respectively. Under the same conditions, the acetate consumption flux was inhibited up to 60% and the glyoxylate cycle and gluconeogenic fluxes decreased from 0.7 and 0.3 mmol h-1 g-1 dw, respectively, to negligible values. We observed a linear correlation of the acetate consumption rate with the sporulation frequency by varying the 2dG concentration. The linear correlation was also verified between the frequency of sporulation and the fluxes through glyoxylate cycle and gluconeogenic pathways. In addition, the same association of inhibition of sporulation and metabolic fluxes was found in other S. cerevisiae strains displaying different potentials of sporulation. The results presented suggest that inhibition of sporulation in the presence of the glucose analog may be attributed, at least in part, to the inhibition of anabolic fluxes and might be associated with catabolite repression.

Hybrids obtained by protoplast fusion with a salt-tolerant yeast

An industrial strain of Saccharomyces cerevisiae was fused with an osmotolerant yeast, Debaryomyces hansenii, to obtain hybrids having increased tolerance to elevated salt concentrations. The hybrids were intermediate to parent species in production of ethanol and polyols.

Transfer of genes for utilization of starch (sta2) and melibiose (mel) to industrial strains of Saccharomyces cerevisiae by single-chromosome transfer, using a kar1 mutant as vector

A method has been developed for the transfer of genes from other yeast strains and species to industrial yeast strains, using a haploid, kar1-1 mutant strain of Saccharomyces cerevisiae as a vector. The sta2 gene, conferring the ability to metabolize starch was transferred from an auxotrophic haploid strain of S. cerevisiae (S. diastaticus) and the melibiose-metabolism (mel) gene(s), from S. kluyveri, to the kar1-1 mutant [K5-5A; (alpha ade2 his4 can1 gal) by normal mating and protoplast fusion. From this strain, the genes were transferred to baker's yeast and brewing yeast strains, which did not utilize starch, and to baker's yeast strains, which did not utilize melibiose, by protoplast fusion, spore-cell pairing, or rare-mating. Strains that utilized starch or melibiose were obtained by all three methods. Pulsed-field gel electrophoresis preparations showed little change in the mobility of the chromosomes of the hybrids. The most probable explanation for the results obtained is that single chromosomes were transferred, first, from the donor strains to the kar1-1 haploid mutant strain, and then from the kar1-1 vector to the recipient industrial strain of S. cerevisiae. The transfer of the genes is probably accomplished through formation of disomic strains and then, in the case of the hybrids that metabolize starch, by integration of the sta2 gene into the genome of the industrial yeast strains.

Effects of changes in the mitochondrial genome on the performance of baking yeasts

Modifications to the mitochondria in baking yeasts affect their performance in dough-raising tests significantly. Conversion of a respiratory-competent baking strain, sensitive to glucose repression, to the petite mutant, yielded a strain which was released from this effect, as shown by the increased development of the cytochrome c peak in the cytochrome spectrum, and which showed a comparably improved dough-raising performance, approaching the levels found for a respiratory-competent strain which was fully derepressed. Replacement of the mitochondria of one strain by those from another, in some cases, improved the performance of the recipient strain, especially if the latter was sensitive to glucose repression. In addition, reduction of glucose repression in single-spore clones derived from the composite strains, as determined by the increased size of the cytochrome c peak, usually segregated 2:2 both for this character and for improved dough-raising capability as well.

Genetic manipulation of non-conventional yeasts by conventional and non-conventional methods

In recent years, yeasts other than those belonging to the species Saccharomyces cerevisiae and Schizosaccharomyces pombe have become increasingly important in industrial processes. Species such as Pichia stipitis, Hansenula polymorpha, Zygosaccharomyces rouxii, Saccharomyces exiguus, Torulaspora delbrueckii, Yarrowia lipolytica and others whose perfect stage is known, can be manipulated genetically by classical methods, but those belonging to the genera Candida (C. utilis, C. tropicalis, C. bombicola, C. zeylanoides, C. boidinii, etc.), Brettanomyces, Cryptococcus, Rhodotorula, and others of the different form genera, cannot be treated in this way. Some, such as Schwanniomyces and Debaryomyces spp., which have a perfect stage, are still difficult to manipulate by conventional means. Genetic manipulation of these yeasts can be approached from two points of view; the first involving improvement of strains by cross-breeding within one species, and the second, the introduction of desirable genes from unrelated species and even from plants or animals. Two techniques are available for construction of industrially-useful strains from these yeasts: protoplast fusion and transformation with chimaeric plasmids containing the gene(s) it is desired to introduce into the recipient strain. The methods for the latter procedure are well known but can be laborious and time-consuming, especially if it is desired to introduce genes from plant or animal sources for production of enzymes, hormones, vaccines and similar products. Protoplast fusion is a simple technique which can be utilized in most laboratories and used for construction of improved yeast strains for brewing, baking, ethanol production and wine-making, either by the fusion of desirable strains of the same species which do not sporulate, or by introduction of genes from non-Saccharomyces species. Methods for fusion of species from different genera and isolation of the desired hybrids have been improved considerably in recent years. We have developed a method for isolation of strains carrying the desired genes by fusing a non-Saccharomyces species with an auxotrophic strain of Saccharomyces cerevisiae and selecting hybrids having the desired characteristics on appropriate media, after which the genes are transferred to the industrial strain by rare-mating, repeated protoplast fusion, or classical mating as required. The advantages and limitations of the method are under investigation.

Non-Utilization of sucrose by the petite mutant of a distiller's yeast

A number of yeast strains are known to be unable to metabolize several sugars (galactose, maltose, α-methylglucoside) when converted to their petite mutants. The basis of this phenomenon is considered to be the loss of the ability to transport the sugars across the cell membrane. However, sucrose is believed to be hydrolyzed before the products are transported into the cell, and the enzyme responsible (invertase) is thought to be either present in the periplasmic space or to be bound to the outer surface of the cytoplasmic membrane. Hence the loss of the ability to metabolize sucrose may infer the impairment of the mechanism for transport of invertase to its normal location outside the cytoplasm. We have found a distiller's yeast strain which has lost the ability to metabolize sucrose when it is converted to the petite mutant, and we report here some of its properties. We have shown that the cell produces invertase, which is present in the cell-free extract, but not in the pellet of cell walls and unbroken cells, though we have not determined whether the enzyme is present in the cytoplasm in the glycosylated or the unglycosylated form. The ability of the strain to ferment sucrose is also impaired in respiratory-competent cells, when the determination is made under anaerobic conditions.

The use of mitochondrial mutants in the isolation of hybrids involving industrial yeast strains

Methods for the isolation of hybrids in which one or both of the parental strains are industrial yeasts, using mitochondrial mutations as markers for the selection and isolation of the hybrids, are described. The systems used included crosses of industrial strains with auxotrophic laboratory strains which also carried a mitochondrial antibiotic resistance mutation, crosses using an auxotrophic laboratory strain and a petite mutant of an industrial strain carrying a rescuable antibiotic resistance mutation, and crosses using a petite mutant of an industrial strain, carrying a rescuable mitochondrial mutation for antibiotic resistance and a respiratory-competent industrial strain which carried some other marker.

Osmotic sensitivity and tolerance and proteinase production in a strain of Saccharomyces

A brewing yeast strain, NCYC 1085, unusual in that it sporulated freely and produced diploid spores, was sensitive to the degree of osmotic tension induced by the addition of 1.5 M KC1 or 2.5 M ethylene glycol to yeast extract-peptone glucose medium, but its progeny, obtained on sporulation and dissection of the resulting asci, included a number of osmotic-tolerant strains, the percentage of which increased as these strains were also sporulated and dissected. In addition, after repeated isolation of single-spore clones for three or four generations, clones producing zones of liquefaction of gelatin ranging in size from zero to large (approximately 1.5 cm) appeared, with the intensity of hydrolysis increasing in clones obtained from the later generations. The isolation of erythromycin-resistant mutants by manganese treatment was also accompanied by the appearance of osmotic-tolerant and gelatin-liquefying clones.

Apparent bisexual behavior of yeast strains obtained from hybridization of industrial yeasts of the genus Saccharomyces with auxotrophic diploids

During a genetic study of some hybrids of brewer's and distiller's yeast strains with impaired sporulation characteristics and genetically marked auxotrophic aa and alpha alpha diploids, strains which showed positive mating reactions with both a and alpha haploid tester strains were observed. These strains proved to be homothallic and sporulated freely. The original hybrids, which appeared to be tetraploid, usually yielded sporulating single-spore clones on dissection of asci formed from them, with few or no mating strains among them. Dissection of asci from these clones yielded some single-spore clones which showed mating reactions with one or the other or both haploid tester strains, and further selection produced strains which on sporulation and dissection yielded single-spore clones which were apparently bisexual and sporulated freely. These strains proved to be homothallic, yielding single-spore clones which were all of the a mating type, and in which the mating reaction and, possibly, the action of the genes for homothallism were impaired, so that sporulating, non-mating diploids and haploids of both mating types were present in cultures originally obtained as single-spore clones.

Removal of resin acids from culture media and kraft-mill effluents by yeasts and some other fungi

Epicoccum nigrum, Rhinocladiella mansonii, Rhodotorula minuta, and Trichosporon cutaneum were tested for their ability to remove resin acids from supplemented kraft-mill effluent and from a medium containing yeast extract as sole nitrogen source. Up to 39% of the resin acid content was removed by all four organisms. The mutagenic activity of the resin acid preparation, as measured by the induction of gene conversion in a strain of Saccharomyces cerevisiae, was low or non-existent.

Yeasts occurring in the effluent disposal basins of a pulp mill in Saskatchewan

The numbers of yeasts in the effluent disposal system of the Prince Albert, Saskatchewan Pulp Mill occasionally reached 1 × 106 cells/liter, but were usually below 5 × 105 cells/liter. Rhodotorula species were commonly isolated and sometimes amounted to half of the population, though usually the relative numbers were considerably lower. The highest counts were found in late summer and early autumn. Bacterial counts varied from 20 × 106 to 74 × 106 cells/ml. Chemical O2 demand (COD) reached about 1200 mg/liter at times, and decreased as the effluent moved through the disposal system, about 40% of the total COD being removed during the treatment process. A considerably wider range of yeast species was found in the pulp mill disposal basins than in the Saskatoon sewage treatment plant. Most of the ascosporogenous yeasts found were Hansenula or Pichia species usually occurring in association with trees, as were many of the Candida species isolated.

Yeasts isolated from some lakes and rivers of Saskatchewan

Yeasts were isolated from lakes in northern Saskatchewan, from the Saskatchewan River between Prince Albert and Cumberland House, and from three small lakes near Saskatoon, two of which form part of recreational areas. Yeast and bacterial counts were relatively low, less than 400 yeast cells/liter, except in samples taken near towns and industrial plants which discharged waste into the rivers or lakes. There was little change in the numbers of yeast cells in waters used for recreational purposes only, but the number of species isolated increased considerably. Most of the yeasts isolated from the other lakes and rivers were species known to occur in association with trees and in soils.

13 C magnetic resonance and structural studies on the mannose-containing polysaccharides of some Pichia and Hansenula spp

Mannose-containing polysaccharides were isolated from the cell walls of six Pichia and Hansenula species. These species were chosen from a group of 24 yeasts having polysaccharides with a similar spectrum, each giving proton magnetic resonance spectra with signals at τ4.24 and τ4.36. The polysaccharides were equated or distinguished by their 13C magnetic resonance (c.m.r.) spectra into three groups based on differing structures. The validity of this technique was borne out by conventional structural determinations. The polysaccharides were found to represent a new structural type, being predominantly linear and containing predominant (1 → 6)-linked α-D-mannopyranose units with (1 → 2)-linked units distributed regularly along the main chains.Some of the signals of the Hansenula capsulata mannan could be assigned to certain carbons indicating that the c.m.r. technique may have uses in structural investigations.

The genetic control of the two types of mannan produced by Saccharomyces cerevisiae

The two mannans formed by different strains of Saccharomyces cerevisiae give proton magnetic resonance spectra (spectral types A and B), which suggests that they differ principally in the presence of a-(1 → 3)-linked mannopyranosyl end units of the side chains of the more complex type (giving spectral type B). The presence or absence of such end units was under the control of a single mendelian gene, since the two types of mannan segregated independently during sporulation. The gene controlling this type of mannan produced was apparently not linked to those controlling the requirements for adenine, uracil, leucine, or histidine. The implications of the findings concerning the mechanism of biosynthesis of yeast mannan are discussed.

Yeasts of the matador soils of Saskatchewan and their ability to use flavonoids

The numbers of yeasts of the soils of the Matador site of the International Biological Program, in southern Saskatchewan, varied from about 1400 to 10 000 cells/g soil in the surface layer and from 600 to 1800 cells/g in the subsurface layers. Most of the cultures isolated were Cryptococcus albidus and its variety diffluens, Cryptococcus laurentii, and Cryptococcus terreus. A few cultures of Cryptococcus dimennae, Rhodotorula minuta, Sporobolomyces pararoseus, and Sporobolomyces salmonicolor were also isolated. Most of the cultures isolated could use rutin and many of them used the other flavonoids tested. Many of them used phloroglucinol and a few used naphthalene.

Yeasts isolated from soils of citrus orchards and citrus waste disposal areas in California and Florida: flavonoid utilization

Yeasts were isolated from soils from citrus orchards and citrus waste disposal areas in California and Florida. Species of Trichosporon, Cryptococcus, and Rhoclotorula were predominant. Strains of Hansenula saturnus, Hansenula californica, Hansenula mrakii, Pichia kluyveri, Saccharomyces rosei, Saccharomyces cerevisiae, and some species of Candida and Torulopsis were also found. The cultures isolated were tested for the ability to use a number of flavonoids. These compounds were used by strains of Trichosporon cutaneum, Cryptococcus albidus and its variety diffluens, Cryptococcus terreus, Cryptococcus lanrentii, Rhodotorula glutinis, Rhodotorula minuta, Rhodotorula rubra, and Candida humicola, but not by the ascosporogenous species or the other Candida species. Contrary to expectations, most of the cultures which used flavonoids were isolated from the orchard soils rather than from the soils of the waste disposal areas.

Yeasts isolated from the South Saskatchewan, a polluted river

Minimum numbers of yeasts isolated from the Saskatchewan River in the summers of 1964 and 1965 ranged from 400 to 500 cells/liter upstream from the city of Saskatoon, to 4600 cells/liter immediately downstream. In the summer of 1968, a period of extremely low water, the counts were 150 cells/liter upstream from the city and 30 000 cells/liter downstream.Proton magnetic resonance spectra of the mannose-containing polysaccharides from representative cultures of the different species isolated were used as an aid in classification. Most of the species were asporogenous, and included representatives of the genera Candida, Trichosporon, Rhodotorula, Torulopsis, and Cryptococcus. Some species of Pichia, Saccharomyces, and Debaryomyces were isolated. The yeasts were mostly introduced into the river with the effluent from the Saskatoon sewage system.

Proton magnetic resonance spectra of the mannans of some new species of Hansenula and their phylogenetic significance

The proton magnetic resonance spectra of the mannose-containing polysaccharides from some new species of Hansenula were obtained and used as an aid in establishing their phylogenetic relationships to other members of the genus. The spectrum of the mannan from Hansenula dimennae is identical with that of the mannan from Hansenula californica. These two haploid species are taxonomically closely related and are adjacent on the same line of the phylogenetic diagram according to Wickerham. Hansenula saturnus var. subsufficiens mannan has a spectrum like those of the mannans of some strains of Hansenula mrakii and Hansenula beijerinckii. The new species Hansenula henricii, Hansenula nonfermentans, and Hansenula glucozyma all form mannans with spectra having characteristic signals at about τ4.24 and τ4.38, as do the spectra of the mannans formed by the other species on the same phylogenetic line, Hansenula polymorpha, Hansenula minuta, and Hansenula wickerhamii. These species have, relatively, DNA's with the highest guanine and cytosine percentages in the genus. Hansenula platypodis, a species which, unlike other Hansenula species, forms ascophores and anastomoses, has DNA with a lower content of guanine plus cytosine. The spectrum of H. platypodis mannan is like that of H. minuta mannan, with the exception of two small signals at τ4.44 and τ4.48 which do not occur in the spectrum of H. minuta mannan.

Yeasts isolated from bumblebee honey from western Canada: identification with the aid of proton magnetic resonance spectra of their mannose-containing polysaccharides

Yeasts were isolated from bumblebee honey collected in the Pincher Creek region of southwestern Alberta and the Melfort and Saskatoon regions of central Saskatchewan. The predominant species isolated were Torulopsis bombicola n. sp., which produces hydroxy fatty acid sophorosides, a Candida species which resembles it in its assimilatory reactions but which does not produce sophorosides, and Saccharomyces rouxii. A few cultures of Debaryomyces phaffii and Candida reukaufii were isolated. The mannans or galactomannans formed by representatives of each group were extracted and their proton magnetic resonance spectra determined and used as an aid in identification of the different species.

Changes produced in hop extract components by yeasts

A number of yeasts, many of which were originally isolated from spoiled beer and similar sources, were tested for their ability to degrade or modify some of the components of hop extract. The yeasts could be divided into three major groups: those which caused little change in the composition of the steam-distillable components of the hop extract – yeast extract medium; those which apparently modified one or more components as determined by the shifting of a major peak on the gas–liquid chromatogram; and those which caused extensive degradation and complete disappearance of the major steam-distillable components of the hop extract medium.

Systematics of the genera Hansenula and Pichia: proton magnetic resonance spectra of their mannans as an aid in classification

The proton magnetic resonance (p.m.r.) spectra of the mannans extracted from a number of species of Hansenula and Pichia were determined, and the species in each genus grouped according to similarities in the p.m.r. spectra. Some of the groups of Pichia species formed mannans having similar spectra to those produced by some species of Hansenula. Several Candida species produced mannans having spectra similar to those of Pichia species. Pichia vanrijii formed a mannan whose spectrum resembled the spectra of the mannans formed by Schwanniomyces species. Pachysolen tannophilus formed a mannan with a spectrum resembling those of Hansenula holstii and Hansenula capsulata. Citeromyces matritensis and its asporogenous form Torulopsis globosa formed mannans unlike those of any other yeast studied.