An inconspicuous identification: Isolation and identification of a novel Pichia species presenting as fungemia following cardiac surgery

Fungemia is common in critically ill patient populations, and is associated with a high rate of mortality, especially when caused by nonalbicans Candida species. Herein, we describe a fatal case of fungemia following cardiothoracic surgery in which the organism, initially identified as Candida inconspicua, represents a novel species: Pichia alaskaensis.

Characterization of heavy metal toxicity in some plants and microorganisms-A preliminary approach for environmental bioremediation

In situ bioremediation processes are important for control of pollution and clean-up of contaminated sites. The study and implementation of such processes can be designed through investigations on natural mechanisms of absorption, biotransformation, bioaccumulation and toxicity of pollutants in plants and microorganisms. Here, the phytotoxic effects of Cr(VI) and Cd(II) on seed germination and plant growth of Lepidium sativum have been examined at various concentrations (30-300 mg/L) in single ion solutions. The studies also addressed the ecotoxicity of metal ions on Azotobacter chroococcum and Pichia sp. isolated from soil. Microbial growth was estimated by weighing the dry biomass and determining the enzymatic activities of dehydrogenase and catalase. The results showed that Cr(VI) and Cd(II) can inhibit L. sativum seed germination and root development, depending on the metal ion and its concentration. The phytotoxic effect of heavy metals was also confirmed by the reduced amounts of dried biomass. Toxicity assays demonstrated the adverse effect of Cr(VI) and Cd(II) on growth of Azotobacter sp. and Pichia sp., manifested by a biomass decrease of more than 50 % at heavy metal concentrations of 150-300 mg/L. The results confirmed close links between phytotoxicity of metals and their bioavailability for phytoextraction. Studies on the bioremediation potential of soils contaminated with Cr(VI) and Cd(II) using microbial strains focusing on Azotobacter sp. and Pichia sp. showed that the microbes can only tolerate heavy metal stress at low concentrations. These investigations on plants and microorganisms revealed their ability to withstand metal toxicity and develop tolerance to heavy metals.

Identifying yeasts using surface enhanced Raman spectroscopy

The molecular fingerprints of yeasts Saccharomyces cerevisiae, Dekkera bruxellensis, and Wickerhamomyces anomalus (former name Pichia anomala) have been examined using surface-enhanced Raman spectroscopy (SERS) and helium ion microscopy (HIM). The SERS spectra obtained from cell cultures (lysate and non-treated cells) distinguish between these very closely related fungal species. Highly SERS active silver nano-particles suitable for detecting complex biomolecules were fabricated using a simple synthesis route. The yeast samples mixed with aggregated Ag nanoparticles yielded highly enhanced and reproducible Raman signal owing to the high density of the hot spots at the junctions of two or more Ag nanoparticles and enabled to differentiate the three species based on their unique features (spectral fingerprint). We also collected SERS spectra of the three yeast species in beer medium to demonstrate the potential of the method for industrial application. These findings demonstrate the great potential of SERS for detection and identification of fungi species based on the biochemical compositions, even in a chemically complex sample.

Impact of seasonality and environmental conditions on yeast diversity from camel's milk collected in Algeria

During this study, we characterized the seasonality's impact and environmental conditions on the yeast diversity from raw camel's milk collected in Algeria. The yeast counts were estimated to 3.55 × 10² CFU mL^-1, with a maximum of 6.3 × 10² CFU mL^-1. The yeasts were categorized phenotypically by API 20C AUX, MALDI-TOF and genetically by sequencing 26S rDNA and ITS1-5.8S-ITS2. The rDNA sequencing approaches revealed 12 species including unusual ones such as Trichosporon asahii, Pichia fermentans, Millerozyma farinosa, Pichia galeiformis, Candida tartarivorans and Pichia manshurica. The most dominant species were T. asahii (23%), P. fermentans (19%) and Rhodotorula mucilaginosa (14%). The high occurrence and large diversity were registered in samples collected during the autumn season, in the semi-arid and arid highlands regions with 0.66 × 10³ CFU mL^-1 and 0.51 × 10³ CFU mL^-1, respectively. Interestingly, T. asahii, R. mucilaginosa, P. fermentans, C. parapsilosis and C. zeylanoides were detected during both spring and autumn.

Evaluation of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for differentiation of Pichia kluyveri strains isolated from traditional fermentation processes

RATIONALE

Non-Saccharomyces yeasts are widespread microorganisms that nowadays have gained importance for their ability to produce volatile compounds which in alcoholic beverages improve aromatic complexity and therefore the overall quality. Their rapid identification and differentiation in fermentation processes is vital for timely decision making.

METHODS

A total of 19 strains of Pichia kluyveri isolated from mezcal, tejuino and cacao fermentations were analyzed with rep-PCR fingerprinting using the primer (GTG)₅ and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) on a Microflex LT mass spectrometer using Biotyper 3.1 software (Bruker Daltonics).

RESULTS

The comparative analysis between MS spectra and rep-PCR patterns obtained from these strains showed a high similarity between both methods. However, minimal differences between the obtained rep-PCR and MALDI-TOF MS clusters could be observed, especially by the presence and/or absence of one or more discriminating peaks even when they have similarities in their main spectra projection, observing that isolates from the same fermentative process were grouped into the same sub-cluster based on their MALDI-TOF MS profiles.

CONCLUSIONS

The data shown suggests that MALDI-TOF MS is a promising alternative technique for rapid, reliable and cost-effective differentiation of native yeast strains isolated from different traditional fermented foods and beverages.

The potential of the newly isolated thermotolerant yeast Pichia kudriavzevii RZ8-1 for high-temperature ethanol production

High potential, thermotolerant, ethanol-producing yeasts were successfully isolated in this study. Based on molecular identification and phylogenetic analysis, the isolated thermotolerant yeasts were clustered in the genera of Pichia kudriavzevii, Candida tropicalis, Candida orthopsilosis, Candida glabrata and Kodamea ohmeri. A comparative study of ethanol production using 160g/L glucose as a substrate revealed several yeast strains that could produce high ethanol concentrations at high temperatures. When sugarcane bagasse (SCB) hydrolysate containing 85g/L glucose was used as a substrate, the yeast strain designated P. kudriavzevii RZ8-1 exhibited the highest ethanol concentrations of 35.51g/L and 33.84g/L at 37°C and 40°C, respectively. It also exhibited multi-stress tolerance, such as heat, ethanol and acetic acid tolerance. During ethanol fermentation at high temperature (42°C), genes encoding heat shock proteins (ssq1 and hsp90), alcohol dehydrogenases (adh1, adh2, adh3 and adh4) and glyceraldehyde-3-phosphate dehydrogenase (tdh2) were up-regulated, suggesting that these genes might play a crucial role in the thermotolerance ability of P. kudriavzevii RZ8-1 under heat stress. These findings suggest that the growth and ethanol fermentation activities of this organism under heat stress were restricted to the expression of genes involved not only in heat shock response but also in the ethanol production pathway.

The Biology of Pichia membranifaciens Killer Toxins

The killer phenomenon is defined as the ability of some yeast to secrete toxins that are lethal to other sensitive yeasts and filamentous fungi. Since the discovery of strains of Saccharomyces cerevisiae capable of secreting killer toxins, much information has been gained regarding killer toxins and this fact has substantially contributed knowledge on fundamental aspects of cell biology and yeast genetics. The killer phenomenon has been studied in Pichia membranifaciens for several years, during which two toxins have been described. PMKT and PMKT2 are proteins of low molecular mass that bind to primary receptors located in the cell wall structure of sensitive yeast cells, linear (1→6)-β-d-glucans and mannoproteins for PMKT and PMKT2, respectively. Cwp2p also acts as a secondary receptor for PMKT. Killing of sensitive cells by PMKT is characterized by ionic movements across plasma membrane and an acidification of the intracellular pH triggering an activation of the High Osmolarity Glycerol (HOG) pathway. On the contrary, our investigations showed a mechanism of killing in which cells are arrested at an early S-phase by high concentrations of PMKT2. However, we concluded that induced mortality at low PMKT2 doses and also PMKT is indeed of an apoptotic nature. Killer yeasts and their toxins have found potential applications in several fields: in food and beverage production, as biocontrol agents, in yeast bio-typing, and as novel antimycotic agents. Accordingly, several applications have been found for P. membranifaciens killer toxins, ranging from pre- and post-harvest biocontrol of plant pathogens to applications during wine fermentation and ageing (inhibition of Botrytis cinerea, Brettanomyces bruxellensis, etc.).

An Outbreak ofPichia anomalaFungemia in a Brazilian Pediatric Intensive Care Unit

Objective:

To report an outbreak ofPichia anomalafungemia that occurred in a Brazilian pediatric intensive care unit (ICU) from October 2002 to January 2004.

Design:

Unmatched case-control study.

Methods:

We randomly selected four control-patients for each case-patient from a list of all patients admitted to the ICU for at least 48 hours during the outbreak. A second control group was composed of all consecutive patients with nosocomial candidemia in the ICU during the outbreak. An environmental study was performed, and genetic relatedness among the clinical isolates was characterized by randomly amplified polymorphic DNA assay.

Results:

During the study period, 1,046 children were admitted to the pediatric ICU, 17 of whom developedP. anomalafungemia (attack rate, 1.6%). The median age was 1.1 years, and the main underlying conditions were congenital malformations (35.3%) and neoplastic diseases (11.8%). The overall mortality rate was 41.2%. Two patients received no antifungal treatment; all of the others were treated with amphotericin B. On multivariate analysis, only the presence of a central venous catheter was significantly associated withP. anomalafungemia. The yeast was not found on healthcare workers' hands or in the environment. Molecular studies showed that the outbreak was caused by a single strain. The distribution of risk factors was similar between patients withP. anomalafungemia and control-patients with candidemia.

Conclusions:

This study highlights the importance ofP. anomalaas an emerging nosocomial fungal pathogen. Patients withP. anomalafungemia seem to have risk factors in common with those who have candidemia.

Efficient removal of zinc by multi-stress-tolerant yeast Pichia kudriavzevii A16

Heavy metal bioaccumulation by growing microorganisms is a potential technique for treating the heavy metal pollution in food materials, e.g. fishery processing wastes. In this study, a multi-stress-tolerant yeast with high Zn tolerance and efficient Zn removal ability was screened and renamed as Pichia kudriavzevii A16 after identification. High salinity and low pH obviously increased the Zn bioaccumulation capacity of P. kudriavzevii A16, contributing to the increasing Zn removal rate of P. kudriavzevii A16 at 0.5 mmol/L Zn from 67.69% to 77.03% and 96.09%, respectively. P. kudriavzevii A16 displayed high specificity of Zn removal at high concentrations of Cu, while high concentrations of Cd significantly inhibited the Zn removal by restraining the yeast growth. P. kudriavzevii A16 possessed more powerful Zn removal ability than Saccharomyces cerevisiae CICC1211 under various environmental stresses. The multi-stress-tolerant P. kudriavzevii A16 can be developed into a potential Zn removal agent using in complex food environments.

Isolation of a Wickerhamomyces anomalus yeast strain from the sandfly Phlebotomus perniciosus, displaying the killer phenotype

The yeast Wickerhamomyces anomalus has been studied for its wide biotechnological potential, mainly for applications in the food industry. Different strains of W. anomalus have been isolated from diverse habitats and recently from insects, including mosquitoes of medical importance. This paper reports the isolation and phylogenetic characterization of W. anomalus from laboratory-reared adults and larvae of Phlebotomus perniciosus (Diptera: Psychodidae), a main phlebotomine vector of human and canine leishmaniasis. Of 65 yeast strains isolated from P. perniciosus, 15 strains were identified as W. anomalus; one of these was tested for the killer phenotype and demonstrated inhibitory activity against four yeast sensitive strains, as reported for mosquito-isolated strains. The association between P. perniciosus and W. anomalus deserves further investigation in order to explore the possibility that this yeast may exert inhibitory/killing activity against Leishmania spp.

Flow-Based Single Cell Deposition for High-Throughput Screening of Protein Libraries

The identification and engineering of proteins having refined or novel characteristics is an important area of research in many scientific fields. Protein modelling has enabled the rational design of unique proteins, but high-throughput screening of large libraries is still required to identify proteins with potentially valuable properties. Here we report on the development and evaluation of a novel fluorescent activated cell sorting based screening platform. Single bacterial cells, expressing a protein library to be screened, are electronically sorted and deposited onto plates containing solid nutrient growth media in a dense matrix format of between 44 and 195 colonies/cm2. We show that this matrix format is readily applicable to machine interrogation (<30 seconds per plate) and subsequent bioinformatic analysis (~60 seconds per plate) thus enabling the high-throughput screening of the protein library. We evaluate this platform and show that bacteria containing a bioluminescent protein can be spectrally analysed using an optical imager, and a rare clone (0.5% population) can successfully be identified, picked and further characterised. To further enhance this screening platform, we have developed a prototype electronic sort stream multiplexer, that when integrated into a commercial flow cytometric sorter, increases the rate of colony deposition by 89.2% to 24 colonies per second. We believe that the screening platform described here is potentially the foundation of a new generation of high-throughput screening technologies for proteins.

The effect of ZnCl2 on green Spanish-style table olive packaging, a presentation style dependent behaviour

BACKGROUND

Zinc chloride has been used previously as a preservative in directly brined olives with promising results. However, this is the first time that the effects of ZnCl2 addition (0-1 g L(-1) ) on green Spanish-style table olive (cv. Manzanilla) packaging has been studied.

RESULTS

The presence of ZnCl2 affected the physico-chemical characteristics of the products; the presence of the Zn led to lower pH values (particularly just after packaging) and titratable and combined acidity values than the control but did not produce clear trends in the colour parameters. No Enterobacteriaceae were found in any of the treatments evaluated. At the highest ZnCl2 concentrations, the lactic acid bacteria were inhibited while, unexpectedly, its presence showed a lower effect than potassium sorbate against the yeast population. Regardless of the use of potassium sorbate or ZnCl2 , the packages had a reduced microbial biodiversity because only Lactobacillus pentosus and Pichia galeiformis were found at the end of the shelf life. With respect to organoleptic characteristics, the presentations containing ZnCl2 were not differentiated from the traditional product.

CONCLUSION

Zinc chloride was less efficient than potassium sorbate as a yeast inhibitor in green Spanish-style olives, showing clear presentation style dependent behaviour for this property. Its presence produced significant changes in chemical parameters but scarcely affected colour or sensory characteristics.

Biocontrol ability and action mechanism of food-isolated yeast strains against Botrytis cinerea causing post-harvest bunch rot of table grape

Strains belonging to the species Saccharomyces cerevisiae, Wickerhamomyces anomalus, Metschnikowia pulcherrima and Aureobasidium pullulans, isolated from different food sources, were tested in vitro as biocontrol agents (BCAs) against the post-harvest pathogenic mold Botrytis cinerea. All yeast strains demonstrated antifungal activity at different levels depending on species and medium. Killer strains of W. anomalus and S. cerevisiae showed the highest biocontrol in vitro activity, as demonstrated by largest inhibition halos. The competition for iron and the ability to form biofilm and to colonize fruit wounds were hypothesized as the main action mechanisms for M. pulcherrima. The production of hydrolytic enzymes and the ability to colonize the wounds were the most important mechanisms for biocontrol activity in A. pullulans and W. anomalus, which also showed high ability to form biofilm. The production of volatile organic compounds (VOCs) with in vitro and in vivo inhibitory effect on pathogen growth was observed for the species W. anomalus, S. cerevisiae and M. pulcherrima. Our study clearly indicates that multiple modes of action may explain as M. pulcherrima provide excellent control of postharvest botrytis bunch rot of grape.

Mutant strains of Pichia pastoris with enhanced secretion of recombinant proteins

Although Pichia pastoris is a popular protein expression system, it exhibits limitations in its ability to secrete heterologous proteins. Therefore, a REMI (restriction enzyme mediated insertion) strategy was utilized to select mutant beta-g alactosidase s upersecretion (bgs) strains that secreted increased levels of a β-galactosidase reporter. Many of the twelve BGS genes may have functions in intracellular signaling or vesicle transport. Several of these strains also appeared to contain a more permeable cell wall. Preliminary characterization of four bgs mutants showed that they differed in the ability to enhance the export of other reporter proteins. bgs13, which has a disruption in a gene homologous to Saccharomyces cerevisiae protein kinase C (PKC1), gave enhanced secretion of most recombinant proteins that were tested, raising the possibility that it has the universal super-secreter phenotype needed in an industrial production strain of P. pastoris.

Pichia anomala (Candida pelliculosa) fungemia in a patient with sickle cell disease

This case report discusses a patient with sickle cell disease who presented with fungemia from Pichia anomala (teleomorph: Candida pelliculosa). The organism was identified as P. anomala by MALDI-TOF VITEK mass spectrometry and VITEK 2 yeast identification card. Pichia anomala should be considered in sickle cell patients with recurrent fungemia.

[Clinical features and homological analysis of Pichia ohmeri-caused hospital-acquired fungemia in premature infants]

OBJECTIVE

To analyze the clinical features of fungemia caused by Pichia ohmeri (P. ohmeri) in neonate intensive care unit and explore its molecular biological characteristics so as to improve its diagnosis and treatment level.

METHODS

The clinical data of 6 infected infants were retrospectively analyzed. The strains obtained from them were identified and homological analysis was performed through randomly amplified polymorphic assay to explore the epidemiological characteristics of this nosocomial infection.

RESULTS

Before the isolation of P. ohmeri, they received intravenous antibacterial therapy for 13 - 45 days. Among them, 4 received mechanical ventilation and 5 had a peripheral insertion of central venous catheters. Five infants were healed after a therapy of caspofungin for 15 - 30 days. One neonate recurred after a 30-day administration of fluconazole. The strain was identified and confirmed as P. ohmeri. RAPD genotyping results showed that all 6 strains were from the same clone. No similar cases occurred after positive control measures despite a negative epidemiological sampling.

CONCLUSIONS

P. ohmeri may cause premature infant fungemia and lead to its spread in hospital. Hospital infection control is a key point. And caspofungin is both safe and effective in the therapy of neonate fungemia.

Aerobic decolorization and degradation of Acid Red B by a newly isolated Pichia sp. TCL

A yeast strain with strong abilities to decolorize various azo dyes aerobically was isolated from the sea mud. The strain designated as TCL was identified as Pichia sp. on the basis of 18S rDNA analysis. More than 90% of Acid Red B (100mg/L) was decolorized within 10h in the Martin Broth at 30°C and 150r/min, and strain TCL could tolerate up to 1000mg/L of the dye. Meantime, the effects of different physicochemical parameters (media, concentrations of glucose, NH(4)Cl, initial dye and NaCl) were investigated to improve the removal efficiency. The significant biodegradation process of Acid Red B rather than inactive surface adsorption was confirmed by UV-vis, HPLC analysis and colorless microbial cells. In addition, the metabolic products and partial degradation pathway were proposed with the help of HPLC-MS analysis. To the best of our knowledge, it is the first time that a yeast strain of Pichia sp. has been reported with the excellent decolorizing ability against azo dyes under shaking conditions. This work conferred the utilization possibility of strain TCL in the biological treatment of dyeing wastewater.

Locally isolated yeasts from Malaysia: identification, phylogenetic study and characterization

Yeasts are a convenient platform for many applications. They have been widely used as the expression hosts. There is a need to have a new yeast expression system to contribute the molecular cloning demands. Eight yeast isolates were screened from various environment sources and identified through ribosomal DNA (rDNA) Internal Transcribed Spacer (ITS). Full sequence of the rDNA ITS region for each isolate was BLASTed and phylogenetic study was constructed by using MEGA4. Among the isolates, isolate WB from 'ragi' (used to ferment carbohydrates) could be identified as a new species in order Saccharomycetales according to rDNA ITS region, morphology and biochemical tests. Isolate SO (from spoiled orange), RT (rotten tomato) and RG (different type of 'ragi') were identified as Pichia sp. Isolates R1 and R2, S4 and S5 (from the surrounding of a guava tree) were identified as Issatchenkia sp. and Hanseniaspora sp., respectively. Geneticin, 50 µg/mL, was determined to be the antibiotic marker for all isolates excepted for isolates RT and SO which used 500 µg/mL and 100 µg/mL Zeocin, respectively. Intra-extracellular proteins were screened for lipolytic activity at 30°C and 70°C. Thermostable lipase activity was detected in isolates RT and R1 with 0.6 U/mg and 0.1 U/mg, respectively. In conclusion, a new yeast-vector system for isolate WB can be developed by using phleomycin or geneticin as the drugs resistance marker. Moreover, strains RT and R1 can be investigated as a novel source of a thermostable lipase.

Ethanol production from alkali-treated rice straw via simultaneous saccharification and fermentation using newly isolated thermotolerant Pichia kudriavzevii HOP-1

In this study, simultaneous saccharification and fermentation (SSF) was employed to produce ethanol from 1% sodium hydroxide-treated rice straw in a thermostatically controlled glass reactor using 20 FPU gds⁻¹ cellulase, 50 IU gds⁻¹ β-glucosidase, 15 IU gds⁻¹ pectinase and a newly isolated thermotolerant Pichia kudriavzevii HOP-1 strain. Scanning electron micrograph images showed that the size of the P. kudriavzevii cells ranged from 2.48 to 6.93 μm in diameter while the shape of the cells varied from oval, ellipsoidal to elongate. Pichia kudriavzevii cells showed extensive pseudohyphae formation after 5 days of growth and could assimilate sugars like glucose, sucrose, galactose, fructose, and mannose but the cells could not assimilate xylose, arabinose, cellobiose, raffinose, or trehalose. In addition, the yeast cells could tolerate up to 40% glucose and 5% NaCl concentrations but their growth was inhibited at 1% acetic acid and 0.01% cyclohexamide concentrations. Pichia kudriavzevii produced about 35 and 200% more ethanol than the conventional Saccharomyces cerevisiae cells at 40 and 45°C, respectively. About 94% glucan in alkali-treated rice straw was converted to glucose through enzymatic hydrolysis within 36 h. Ethanol concentration of 24.25 g l⁻¹ corresponding to 82% theoretical yield on glucan basis and ethanol productivity of 1.10 g l⁻¹ h⁻¹ achieved using P. kudriavzevii during SSF hold promise for scale-up studies. An insignificant amount of glycerol and no xylitol was produced during SSF. To the best of our knowledge, this is the first study reporting ethanol production from any lignocellulosic biomass using P. kudriavzevii.

Antimicrobial activity of weak acids in liquid feed fermentations, and its effects on yeasts and lactic acid bacteria

BACKGROUND

The efficacy of weak organic acids in the control of yeasts in pig liquid feed was studied taking into account the effects on lactic acid bacteria (LAB) responsible for beneficial fermentation.

RESULTS

The yeast population in pig liquid feed was taxonomically identified. Kazachstania exigua, Debaryomyces hansenii and Pichia deserticola dominated the fermentation in liquid feed and whey. Pichia deserticola was found in whey and foaming liquid feed and dominated the fermentation after incubation. The sensitivity of the isolates against weak acids was measured in culture medium as well as in fermented and non-fermented liquid feed. Formic acid and potassium sorbate successfully reduced the growth of yeasts in all media without interfering with LAB development. Both of these organic acids showed an increased antifungal effect when used in liquid feed fermented by a Lactobacillus plantarum strain.

CONCLUSION

The loss of energy, reduced palatability and other practical problems due to the high growth of yeasts in fermented liquid diets can be reduced by organic acids without affecting lactic acid fermentation.

Exploring the yeast biodiversity of green table olive industrial fermentations for technological applications

In recent years, there has been an increasing interest in identifying and characterizing the yeast populations associated with diverse types of table olive elaborations because of the many desirable technological properties of these microorganisms. In this work, a total of 199 yeast isolates were directly obtained from industrial green table olive fermentations and genetically identified by means of a RFLP analysis of the 5.8S-ITS region and sequencing of the D1/D2 domains of the 26S rDNA gene. Candida diddensiae, Saccharomyces cerevisiae and Pichia membranifaciens were the most abundant yeast species isolated from directly brined Aloreña olives, while for Gordal and Manzanilla cultivars they were Candida tropicalis, Pichia galeiformis and Wickerhamomyces anomalus. In the case of Gordal and Manzanilla green olives processed according to the Spanish style, the predominant yeasts were Debaryomyces etchellsii, C. tropicalis, P. galeiformis and Kluyveromyces lactis. Biochemical activities of technological interest were then qualitatively determined for isolates belonging to all yeast species. This preliminary screening identified two isolates of W. anomalus with interesting properties, such as a strong β-glucosidase and esterase activity, and a moderate catalase and lipolytic activity, which were also confirmed by quantitative assays. The results obtained in this survey show the potential use that some yeast species could have as starters, alone or in combination with lactic acid bacteria, during olive processing.

Autochthonous yeasts associated with mature pineapple fruits, freshly crushed juice and their ferments; and the chemical changes during natural fermentation

This study investigated autochthonous yeasts and their functions in the spontaneous fermentation of freshly crushed pineapple juice samples collected from two different areas of both Thailand and Australia. Hanseniaspora uvarum and Pichia guilliermondii were the main yeast species observed on the fruit skins of Thai samples, and also in the fresh juice and ferments of all samples from both countries. P. guilliermondii was consistently present as the dominant species during the early stage of the fermentation, whereas H. uvarum became more prevalent towards the end of the six-day fermentation period, with populations increasing from an initial level of approximately 5 log CFU/mL to approximately 8 log CFU/mL at the end of fermentation. The ethanol levels in samples from both regions of Thailand were maximal at 2 days of fermentation, reaching approximately 1 to 2% (v/v) but then declined thereafter. In contrast, in the Australian samples ethanol levels continued to increase over the entire six-day fermentation period and reached approximately 3 to 4% (v/v). A significant decrease in citric acid and increase in lactic acid levels were observed throughout the fermentation period in the samples from Thailand, but not in those from Australia where the different acid contents (and pH) were relatively stable. The other wine yeasts and, in particular, Saccharomyces yeasts, were not found in any of sampled fermentation systems that is apparently different from the other fruit juices. These findings suggested that the freshly crushed pineapple juice may possibly have some effects on the other autochthonous yeasts having important role in alcoholic fermentation.

Polymerase chain reaction assay for specific identification of Candida guilliermondii (Pichia guilliermondii)

The incidence rates of fungemia caused by Candida guilliermondii have been increasing over the past several years. Although still relatively rare (1.3% of all cases of fungemia in Japan), most cases of C. guilliermondii fungemia occur in patients with cancer or hematological malignancy and their mortality rate is high. As C. guilliermondii tends to be resistant to various antifungal agents, early identification of this pathogen and treatment with an appropriate antifungal agent are required to improve survival rates in these patients. However, it is extremely difficult to differentiate C. guilliermondii (Pichia guilliermondii) from members of the C. famata complex. To date, identification based on DNA sequencing has been the only reliable method for the identification of fungal groups. Here, we used a polymerase chain reaction (PCR)-based method that we developed for the simple and reliable identification of C. guilliermondii (P. guilliermondii). A pair of specific primers was designed corresponding to the 18S rDNA sequence. The PCR system was applied to isolates from fungemia patients. These yeasts could not be identified with CHROMagar Candida, but were successfully identified using this PCR-based system.

Kodamaea ohmeri infection in a neonate

Kodamaea ohmeri is an extremely uncommon human pathogenic yeast. It causes opportunistic infection in immunocompromised hosts. We report a case of Kodamaea ohmeri fungemia in a preterm neonate who succumbed despite antifungal therapy.

Spoilage yeasts in Patagonian winemaking: molecular and physiological features of Pichia guilliermondii indigenous isolates

Yeasts belonging to the genus Dekkera/Brettanomyces, especially the species Dekkera bruxellensis, have long been associated with the production of volatile phenols responsible for off-flavour in wines. According to recent reports, the species Pichia guilliermondii could also produce these compounds at the initial stages of fermentation. Based on the abundance of P. guilliermondii in Patagonian winemaking, we decided to study the relevance of indigenous isolates belonging to this species as wine spoilage yeast. Twenty-three indigenous isolates obtained from grape surfaces and red wine musts were analyzed in their capacity to produce volatile phenols on grape must. The relationship between molecular Random Amplified Polymorphic DNA (RAPD) and physiological (killer biotype) patterns detected in indigenous populations of P. guilliermondii and volatile phenol production was also evaluated. Different production levels of 4-ethylphenol, 4-vinylguaiacol and 4-ethylguaiacol were detected among the isolates; however, the values were always lower than those produced by the D. bruxellensis reference strain in the same conditions. High levels of 4-vinylphenol were detected among P. guilliermondii indigenous isolates. The combined use of RAPD and killer biotype allowed us to identify the isolates producing the highest volatile phenol levels.

Debaryomyces hansenii (Candida famata), a rare human fungal pathogen often misidentified as Pichia guilliermondii (Candida guilliermondii)

Debaryomyces hansenii is a hemiascomycetous yeast commonly found in natural substrates and in various types of cheese. Pichia guilliermondii is widely distributed in nature and is a common constituent of the normal human microflora. Both species have been described in human infections but are extremely difficult to differentiate phenotypically. Thus, frequent errors in identification occur. The 62 clinical and environmental isolates sent between 2000 and 2007 to the French National Reference Center for Mycoses and Antifungals as D. hansenii or P. guilliermondii were analyzed by using the carbon assimilation pattern, the presence of pseudohyphae, and sequencing of the ITS and D1/D2 regions of the rRNA gene. The objective of this study was to assess using nucleotide sequences whether phenotypic identification was accurate and whether phenotypic characteristics could be used to differentiate the two species when sequencing was not available. We found that 58% of the isolates were misidentified and belong to seven different species: P. guilliermondii, P. caribbica, P. jadinii, D. hansenii, Candida palmioleophila, C. haemulonii type II, and Clavispora lusitaniae. In conclusion, D. hansenii may not be as common a human pathogen as previously thought. Sequencing of either ITS or D1/D2 regions is a good tool for differentiating the species more frequently confused with D. hansenii, keeping in mind that reliable databases should be used.

Lactic acid bacteria and yeasts associated with gowé production from sorghum in Bénin

AIMS

To identify the dominant micro-organisms involved in the production of gowé, a fermented beverage, and to select the most appropriate species for starter culture development.

METHODS AND RESULTS

Samples of sorghum gowé produced twice at three different production sites were taken at different fermentation times. DNA amplification by internal transcribed spacer-polymerase chain reaction of 288 lactic acid bacteria (LAB) isolates and 16S rRNA gene sequencing of selected strains revealed that the dominant LAB responsible for gowé fermentation were Lactobacillus fermentum, Weissella confusa, Lactobacillus mucosae, Pediococcus acidilactici, Pediococcus pentosaceus and Weissella kimchii. DNA from 200 strains of yeasts was amplified and the D1/D2 domain of the 26S rRNA gene was sequenced for selected isolates, revealing that the yeasts species were Kluyveromyces marxianus, Pichia anomala, Candida krusei and Candida tropicalis.

CONCLUSIONS

Gowé processing is characterized by a mixed fermentation dominated by Lact. fermentum, W. confusa and Ped. acidilactici for the LAB and by K. marxianus, P. anomala and C. krusei for the yeasts.

SIGNIFICANCE AND IMPACT OF THE STUDY

The diversity of the LAB and yeasts identified offers new opportunities for technology upgrading and products development in gowé production. The identified species can be used as possible starter for a controlled fermentation of gowé.

Isolation and Characterization of Xylitol-Producing Yeasts from the Gut of Colleopteran Insects

A total of 35 yeasts were isolated from the gut of beetles collected from Hyderabad city, India. Twenty of these yeasts utilized xylose as a sole carbon source but only 12 of these converted xylose to xylitol. The ability to convert xylose to xylitol varied among the isolates and ranged from 0.12 to 0.58 g/g xylose. Based on the phenotypic characteristics and phylogenetic analysis of the D1/D2 domain sequence of 26S rRNA gene, these isolates were identified as members of Pichia, Candida, Issatchenkia, and Clavispora. Strain YS 54 (CBS 10446), which was phylogenetically similar to Pichia caribbica and which formed hat-shaped ascospore characteristics of the genus Pichia, was the best xylitol producer (0.58 g xylitol/g xylose). YS 54 was also capable of producing xylitol from sugarcane bagasse hydrolysate and the efficiency of conversion was 0.32 g xylitol/g xylose after 20 cycles of adaptation in medium containing sugarcane bagasse hydrolysate.

Pichia farinosa bloodstream infection in a lymphoma patient

We describe a case of Pichia farinosa bloodstream infection in a lymphoma patient. Phenotypic methods failed to identify the isolate, which was identified by sequence-based methods. This case highlights the importance of implementing molecular methods for the identification of rare fungal pathogens.

Pichia cecembensissp. nov. isolated from a papaya fruit (Carica papaya L., Caricaceae)

The ascogenous yeast YS16T was isolated from a decaying papaya fruit. Phenotypic traits such as multilateral budding, spheroidal or elongate shape, pseudohyphae formation, asci with one or more ascospores, ability to ferment d-glucose, inability to assimilate nitrate and the presence of Q7 ubiquinone suggest its affiliation to the genus Pichia. The nearest phylogenetic neighbor, based on D1/D2 domain sequence of the 26S rRNA gene and ITS region sequence, was identified as Issatchenkia orientalis (NRRL Y-5396T, a synonym of Pichia kudriavzevii) with similarities of 98.2% and 97% respectively. In addition to the difference in the D1/D2 and ITS region sequence, YS16T differs from I. orientalis with respect to a number of phenotypic traits. However, in the phylogenetic analysis, YS16T showed close relatedness to the P. membranifaciens clade. Thus, it is proposed to assign the status of a new species to YS16T, for which the name P. cecembensis sp. nov. is proposed. The type strain of P. cecembensis sp. nov. is YS16T (=NRRL Y-27985T=JCM 13873T=CBS 10445T).

Identification and characterization of yeast isolated from the elaboration of seasoned green table olives

The purpose of this study was to investigate the yeast population during the processing of green table olives. In the fresh olives, yeast were found at concentrations of around 3.0 log cfu/g, with Cryptococcus spp. being predominant. In the brine, the yeast concentrations were greater than 4.9 log cfu/ml, with Pichia anomala, Kluyveromyces marxianus, and Saccharomyces cerevisiae being the predominant species. Unlike the yeast isolated from the fresh olives, the strains obtained from the olive brine mostly showed low pectolytic but high catalase activities. Some of these strains also exhibited other biochemical desirable properties for the fermentation of green table olives, including their lipolytic activities and their assimilation or production of organic acids in the brine. Seven strains in particular of P. anomala, K. marxianus, S. cerevisiae, and Candida maris showed the best properties for use in trials as starter culture in pilot fermenters.

Antifungal drug susceptibility profile of Pichia anomala isolates from patients presenting with nosocomial fungemia

In vitro susceptibility of 58 isolates of Pichia anomala to five antifungal drugs using two broth microdilution methods (CLSI and EUCAST) was analyzed. Low susceptibility to itraconazole was observed. Fluconazole, voriconazole, amphotericin B, and caspofungin showed good antifungal activity, although relatively high drug concentrations were necessary to inhibit the isolates.

Ogataea thermophila sp. nov., the teleomorph of Candida thermophila

Ascospore formation was observed in the type strain of Candida thermophila Shin K-S, Shin YK, Yoon and Park on some yeast sporulation media. In addition, a further sporulating strain was found that proved to be conspecific with C. thermophila on the basis of sequences of the D1/D2 domain of the large-subunit (26S) rRNA gene and the internal transcribed spacer (ITS)1-5.8S rRNA gene - ITS2 region. Therefore, Ogataea thermophila Péter, Tornai-Lehoczki, Shin K-S & Dlauchy sp. nov. is proposed as the teleomorph of C. thermophila. The type strain is Y94(T)=JCM 10994(T)=KCCM 50661(T)=KCTC 17233(T).

PCR-based identification and strain typing of Pichia anomala using the ribosomal intergenic spacer region IGS1

Frequent outbreaks of Pichia anomala fungaemia in paediatric patients have warranted the development of a rapid identification system for this organism. This study describes a specific PCR-based method targeting the rRNA gene intergenic spacer region 1 (IGS1) for rapid identification of Pichia anomala isolates and characterization at the strain level. These methods of species identification and strain typing were used on 106 isolates of Pichia anomala (77 from a previously described outbreak and 29 isolated post-outbreak from the same hospital). Using conventional morphological and biochemical methods, 11 strains isolated during the outbreak were misidentified as P. anomala. blast analysis of sequences of internal transcribed spacer (ITS) regions of rRNA genes confirmed that they were Pichia guilliermondii (eight isolates) and Debaryomyces hansenii (three isolates). Strain typing of Pichia anomala isolates confirmed the previous finding of a point-source outbreak. The results suggest that IGS sequences and their polymorphisms could be exploited for similar typing methods in other organisms.

Kodamaea ohmeri isolates from patients in a university hospital: identification, antifungal susceptibility, and pulsed-field gel electrophoresis analysis

Data on clinical isolates of Kodamaea (Pichia) ohmeri, an emerging fungal pathogen, are scarce. Over the past 5 years, we identified yeast isolates from nine patients with fungemia as K. ohmeri by using the API 20C system. Here, we reanalyzed these isolates first by sequencing the internal transcribed spacer 2 (ITS2) regions and then by growing the isolates on CHROMagar Candida medium and subjecting them to pulsed-field gel electrophoresis (PFGE). Based on their ITS2 sequences, six of the nine isolates were confirmed as K. ohmeri, while the others were identified as Candida haemulonii (n = 2) and Candida parapsilosis (n = 1). PFGE karyotyping of the K. ohmeri isolates revealed similar major bands, and their colonies showed a characteristic color change from pink to blue when grown on CHROMagar Candida medium for more than 48 h. For K. ohmeri, the ranges of MICs of fluconazole, voriconazole, caspofungin, and micafungin were 2 to 32 mug/ml, 0.03 to 0.5 mug/ml, 0.125 to 0.25 mug/ml, and 0.03 to 0.06 mug/ml, respectively. Restriction endonuclease analysis of genomic NotI-digested DNA (REAG-N) from isolates from different patients produced unique patterns, suggesting that the fungemia had occurred sporadically. This study determined that ITS2 sequence data, PFGE karyotypes, and CHROMagar Candida chromogenic culture medium are reliable diagnostic tools for identifying K. ohmeri while REAG-N is useful for genotyping the clinical isolates of K. ohmeri.

Nosocomial infection in newborns by Pichia anomala in a Brazilian intensive care unit

Disseminated candidiasis is the most common nosocomial fungal infection, and Candida albicans has been reported to account for 50% to more than 70% of cases of invasive candidiasis. However, recent reports have also suggested the emergence of infections caused by non-albicans species. In addition, less-common pathogenic yeasts (Malassezia, Trichosporon, Rhodotorula, Debaryomyces and Pichia) have recently been reported, with increased frequency, as causes of nosocomial infections with high mortality. This article describes two cases of fungemia caused by Pichia anomala in newborns that occurred in an intensive care unit (ICU), in November 2004 at the Instituto da Criança (Pediatric Institute) of the Hospital das Clínicas of the School of Medicine, São Paulo University, Brazil. The principal factors related to virulence (proteinase and phospholipase) and the susceptibility of the isolated strains to antifungal agents were also evaluated, and the biotype of each strain was determined through the use of an epidemiological marker (killer biotype).

Kodamaea (Pichia) ohmeri fungaemia in a premature neonate

Kodamaea ohmeri is a yeast that rarely causes human infections. The first case of K. ohmeri fungaemia in a premature neonate is reported; it was successfully treated with liposomal amphotericin B. Biochemical identification of the yeast was performed by Vitek II and API and was confirmed by rRNA gene sequencing. K. ohmeri as a human pathogenic yeast is uncommon to hospitalized neonates and immunocompromised individuals.

Molecular typing of the yeast species Dekkera bruxellensis and Pichia guilliermondii recovered from wine related sources

A total of 63 strains of Dekkera bruxellensis and 32 strains of Pichia guilliermondii isolated from wine related environments were identified by restriction analysis of the 5.8S-ITS region of the rDNA. These strains were subjected to intraspecific discrimination using mtDNA restriction and RAPD-PCR analysis. The isolates identified as D. bruxellensis yielded 3 different molecular patterns of mtDNA restriction using the endonuclease HinfI. The pattern A was the most frequent (58 strains) among strains from different sources, regions and countries. Pattern B (4 strains) and C (one strain) were determined in isolates from Portuguese wines. The discrimination among the pattern A strains was achieved by a RAPD-PCR assay with 3 primers (OPA-2, OPA-3 and OPA-9). A total of 12 haplotypes were obtained with the combination of the patterns provided by the 3 OPAs. The pattern 2 was the most frequent and extensively distributed being found in strains from different countries and from different sources like wine, barrique wood and insects. The strains of P. guilliermondii were characterized with restriction of mtDNA using the endonuclease HinfI yielding 7 different restriction patterns. These patterns were associated with different efficiencies of 4-ethylphenol production. Patterns A to D corresponded to 19 strains producing low levels of 4-ethylphenol (<1 mg/l) while patterns F and G grouped 13 strains producing high levels of 4-ethylphenol (>50 mg/l), when grown in synthetic media supplemented with 100 mg/l of p-coumaric acid. The high degree of polymorphism observed shows that intraspecific typing is essential for accurate yeast dissemination studies in wine related environments.

Pichia thermomethanolica sp. nov., a novel thermotolerant, methylotrophic yeast isolated in Thailand

Three strains (N002, N069 and PT31T) of a novel thermotolerant methylotrophic yeast species belonging to the genus Pichia were isolated from soil collected in Thailand by three consecutive enrichments in methanol broth at room temperature. They were categorized as thermotolerant strains on the basis of their good growth below 20 °C and up to a high temperature (37 °C). The major characteristics of the three strains included the following and placed them in the genus Pichia: the formation of four helmet-/hat-shaped ascospores in a deliquescent ascus that might be unconjugated or produced by conjugation between a cell and its bud or between independent cells; multilateral budding; the presence of ubiquinone Q-7; negative for Diazonium blue B colour and urease reactions; and the absence of arthrospores and ballistospores. The three strains differed by one to three nucleotide substitutions in the sequences of the D1/D2 domain of the large-subunit rDNA sequence. Phylogenetic analysis revealed that their closest species was Pichia dorogensis, but with 11–13 nucleotide substitutions in 554 nt. The phenotypic characteristics of the three strains were the same. The strains could be distinguished from P. dorogensis by a number of phenotypic characteristics. On the basis of the above findings, these three strains were assigned to a single novel species of Pichia, for which the name Pichia thermomethanolica sp. nov. is proposed. The type strain is PT31T (=BCC 16875T=JCM 12984T=CBS 10098T).

An outbreak of Pichia ohmeri infection in the paediatric intensive care unit: case reports and review of the literature

Since the first report in 1998, 10 cases of Pichia ohmeri infection have been reported in the literature. Here we present two new cases of P. ohmeri infection in the paediatric age group. The first case was an 8-month-old male infant, who was admitted with fever, convulsions and altered consciousness. Conservative therapy was started with a presumptive diagnosis of encephalitis. The patient failed to respond to the given treatments and died on the 21st day of hospitalisation. The second case was a 10-year-old male with B-cell acute lymphoblastic leukaemia. He was hospitalised with neutropenic fever. He was discharged after 3 weeks of therapy. In both cases P. ohmeri was identified in blood samples. Growing evidence indicates that P. ohmeri should be added to the lengthening list of opportunistic fungal pathogens that can cause infection in all ages, including infants, and particularly in those who are immunocompromised.

PCR-fingerprinting and RAPD approaches for tracing the source of yeast contamination in a carbonated orange juice production chain

AIMS

To investigate the sort and the origin of the contamination of a packed fruit juice.

METHODS AND RESULTS

Fifty-eight yeast isolates were collected in a survey of two different visits to a carbonated orange juice factory. In each visit, samples were collected, six times, from seven points in the production chain. For each visit, no significant differences were observed among the yeast average values obtained in the control points considered. The random amplified polymorphic DNA (RAPD) with primer P24 and the PCR-fingerprinting with the microsatellites primers (GTG)5 and (GAC)5 were used, in order to discriminate the isolates, rendering 29 composite profiles; the most frequent one (24/58) was profile c, which included the yeast isolates from the final product and strains isolated before and after the pasteurization of the juice. These contaminant strains were identified as Pichia galeiformis by sequence analysis of D1/D2 26S rRNA gene.

CONCLUSIONS

The results obtained point to an inefficient pasteurization of the juice related to the fouling of the heat-transfer surfaces of the plate-type exchanger.

SIGNIFICANCE AND IMPACT OF THE STUDY

The combination of PCR-fingerprinting and RAPD assays showed to be very useful in tracking the route of contamination in a carbonated juice production chain.

Pichia myanmarensis sp. nov., a novel cation-tolerant yeast isolated from palm sugar in Myanmar

Four halotolerant yeast strains, M21T, M34-1, HS054 and D41, were isolated from various foods in South-East Asia. These isolates were most closely related to Pichia anomala, with which each strain had from zero to two differences in the 26S rDNA D1/D2 domain nucleotide sequence; for this reason, they were thought to be the same as, or sister species of, P. anomala. Of the four yeast isolates, only one strain, M21T, had an 18S rDNA sequence that differed from those of P. anomala IFO 10213T and the other three isolates, having 20 substitutions and two gaps. Strain M21T showed lower cation (Li+) tolerance (⩽0·3 M LiCl) than P. anomala IFO 10213T or the other three strains (⩽0·5 M LiCl). Furthermore, the DNA–DNA hybridization data indicated that M21T was clearly distinct from P. anomala IFO 10213T and the other three isolates. The ability of strain M21T to assimilate d-arabinose distinguished it from P. anomala IFO 10213T and the other three isolates; it also differed in that it was able to grow at 37 and 40 °C. Strain M21T grew by multilateral budding, produced persistent asci, in which between one and four hat-shaped ascospores were formed, and contained ubiquinone Q-7. On the basis of this polyphasic characterization, strain M21T represents a novel species within the Q-7-containing group of the genus Pichia, for which the name Pichia myanmarensis is proposed. The type strain is M21T (=NBRC 11090T=JCM 12922T=CBS 9786T).

Oxoester oxidoreductase activities in new isolates of from apple, grape and cane juices

Thirty-nine yeasts isolated from apple, grape and cane juices were screened for their oxidoreductase activity. The two strains of Pichia, one isolated from apple and one from cane juices, appear to be promising strains for oxidoreductase activity on alpha-oxoesters. They showed similar high yields in converting ethyl pyruvate to ethyl lactate as Saccharomyces spp. (86.6% and 85.3% versus 86.6%), and higher yields in the reduction of alpha-oxocarboxylic esters (ketopantolactone to pantolactone: 74% and 73.3%, respectively) compared to Saccharomyces spp. (yield 60%).

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

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 1.1 to 3.2 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 Hansenulawingeii migration profiles led to the estimate of K strain genome size at 11.7 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 non-isogenic 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 elsewhere for Hansenula anomala, while Hansenula is included as a synonym of Pichia. This warrants further studies to investigate this taxonomic relationship.

sp. nov., a sporogenous methylotrophic yeast from tree exudates

Thirteen strains of a new ascospore-forming, methanol-assimilating yeast species were isolated from sap exudates of Sclerolobium sp. (carvoeiro) in two forest fragments in the state of Toncantins, Brazil, and from Hymenaea courbaril (guapinol, jatobá) in Guanacaste Province, Costa Rica. Analysis of the sequences of the D1/D2 large-subunit ribosomal DNA showed that the species belongs to the genus Ogataea (syn. Pichia), and it was described as Ogataea falcaomoraisii. The closest relatives are Candida ortonii and C. nemodendra. The type culture is UFMG-T264-1T (= CBS 9814T = NRRL Y-27756).

The yeast flora of some decaying mushrooms on trunks of living trees

Several ascomycetous and basidiomycetous yeasts were isolated from rotten mushrooms on the trunks of beech and tamarisk trees. One strain, identified as the novel species Cryptococcus allantoinivorans, assimilated allantoin as the sole carbon source. Phylogenetically it belongs to the C. laurentii complex, Papiliotrema bandonii being the closest relative. Some ascomycetous strains could not be distinguished from Pichia guillermondii, but deviated considerably in rDNA sequences. In addition to these species, both decaying mushrooms were inhabited by more common species, viz. Candida albicans, C. saitoana, Rhodotorula mucilaginosa, Trichosporon asahii, T. multisporum and T. porosum. The basidiomycetous yeasts, except R. mucilaginosa, assimilated some polysaccharides of plant origin.

Tup1p is important for peroxisome degradation

In the yeast Hansenula polymorpha peroxisomes are selectively degraded upon a shift of cells from methanol to glucose-containing media. We identified the H. polymorpha TUP1 gene by functional complementation of the peroxisome degradation deficient mutant pdd2-4. Tup1 proteins function in transcriptional repression of specific sets of genes involved in various cellular processes. Our combined data indicate that H. polymorpha TUP1 is involved in regulation of the switch between peroxisome biogenesis and selective degradation. The initial DNA fragment that complemented H. polymorpha pdd2-4 contained a second gene, encoding H. polymorpha Vps4p. Deletion of the VPS4 gene did not affect selective peroxisome degradation.

Pichia anomala fungaemia in immunocompromised children. Fallbericht. Pichia anomala-Fungamie bei immunkompromittierten Kindern

Pichia anomala is an emerging yeast causing serious nosocomial infections in newborn and immunocompromised children. We describe nosocomial port catheter infection due to P. anomala in three children who were receiving cancer chemotherapy, bloodstream infection in a preterm infant and in an infant with severe combined immunodeficiency. All patients were treated with amphotericin B. All isolates were susceptible to amphotericin B and fluconazole. No recurrence was observed during follow-up in four of five patients. The common clinical feature in all of our patients was the presence of prior antimicrobial therapy.