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Issues in identifying germ tube positive yeasts by conventional methods.

ABSTRACT: Candida speciation is vital for epidemiology and management of candidiasis. Nonmolecular conventional methods often fail to identify closely related germ tube positive yeasts from clinical specimens. The present study was conducted to identify these yeasts and to highlight issues in conventional versus molecular methods of identification. A total of 98 germ tube positive yeasts from high vaginal swabs were studied over a 12-month period. Isolates were examined with various methods including growth at 42 °C and 45 °C on Sabouraud dextrose agar (SDA), color development on CHROMagar Candida medium, chlamydospore production on corn meal agar at 25 °C, carbohydrate assimilation using ID 32C system, and polymerase chain reaction using a single pair of primers targeting the hyphal wall protein 1 (Hwp1) gene. Of all the isolates studied, 97 were molecularly confirmed as C. albicans and one isolate was identified as C. dubliniensis. No C. africana was detected in this study. The molecular method used in our study was an accurate and useful tool for discriminating C. albicans, C. dubliniensis, and C. africana. The conventional methods, however, were less accurate and riddled with many issues that will be discussed in further details.

SUBMITTER: Yazdanpanah A

PROVIDER: S-EPMC6807331 | biostudies-literature | 2014 Jan

REPOSITORIES: biostudies-literature

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Issues in identifying germ tube positive yeasts by conventional methods.

Yazdanpanah Atta A Khaithir Tzar Mohd Nizam TM

Journal of clinical laboratory analysis 20131227 1

Candida speciation is vital for epidemiology and management of candidiasis. Nonmolecular conventional methods often fail to identify closely related germ tube positive yeasts from clinical specimens. The present study was conducted to identify these yeasts and to highlight issues in conventional versus molecular methods of identification. A total of 98 germ tube positive yeasts from high vaginal swabs were studied over a 12-month period. Isolates were examined with various methods including grow ...[more]

PMID: 24375729

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Project description:Lignocellulosic biomass is an attractive raw material for the sustainable production of chemicals and materials using microbial cell factories. Most of the existing bioprocesses focus on second-generation ethanol production using genetically modified Saccharomyces cerevisiae, however, this microorganism is naturally unable to consume xylose. Moreover, extensive metabolic engineering has to be carried out to achieve high production levels of industrially relevant building blocks. Hence, the use of non-Saccharomyces species, or non-conventional yeasts, bearing native metabolic routes, allows conversion of a wide range of substrates into different products, and higher tolerance to inhibitors improves the efficiency of biorefineries. In this study, nine non-conventional yeast strains were selected and screened on a diluted hemicellulosic hydrolysate from Birch. Kluyveromyces marxianus CBS 6556, Scheffersomyces stipitis CBS 5773, Lipomyces starkeyi DSM 70295, and Rhodotorula toruloides CCT 7815 were selected for further characterization, where their growth and substrate consumption patterns were analyzed under industrially relevant substrate concentrations and controlled environmental conditions in bioreactors. K. marxianus CBS 6556 performed poorly under higher hydrolysate concentrations, although this yeast was determined among the fastest-growing yeasts on diluted hydrolysate. S. stipitis CBS 5773 demonstrated a low growth and biomass production while consuming glucose, while during the xylose-phase, the specific growth and sugar co-consumption rates were among the highest of this study (0.17 h-1 and 0.37 g/gdw*h, respectively). L. starkeyi DSM 70295 and R. toruloides CCT 7815 were the fastest to consume the provided sugars at high hydrolysate conditions, finishing them within 54 and 30 h, respectively. R. toruloides CCT 7815 performed the best of all four studied strains and tested conditions, showing the highest specific growth (0.23 h-1), substrate co-consumption (0.73 ± 0.02 g/gdw*h), and xylose consumption (0.22 g/gdw*h) rates. Furthermore, R. toruloides CCT 7815 was able to produce 10.95 ± 1.37 gL-1 and 1.72 ± 0.04 mgL-1 of lipids and carotenoids, respectively, under non-optimized cultivation conditions. The study provides novel information on selecting suitable host strains for biorefinery processes, provides detailed information on substrate consumption patterns, and pinpoints to bottlenecks possible to address using metabolic engineering or adaptive evolution experiments.

Project description:BackgroundIn studies publishing identifying personal information, obtaining consent is regarded as necessary, as it is impossible to ensure complete anonymity. However, current journal practices around specific points to consider when obtaining consent, the contents of consent forms and how consent forms are managed have not yet been fully examined. This study was conducted to identify potential issues surrounding consent to publish identifying personal information.MethodsContent analysis was carried out on instructions for authors and consent forms developed by academic journals in four fields (as classified by Journal Citation Reports): medicine general and internal, genetics and heredity, pediatrics, and psychiatry. An online questionnaire survey of editors working for journals that require the submission of consent forms was also conducted.ResultsInstructions for authors were reviewed for 491 academic journals (132 for medicine general and internal, 147 for genetics and heredity, 100 for pediatrics, and 112 for psychiatry). Approximately 40% (203: 74 for medicine general and internal, 31 for genetics and heredity, 58 for pediatrics, and 40 for psychiatry) stated that subject consent was necessary. The submission of consent forms was required by 30% (154) of the journals studied, and 10% (50) provided their own consent forms for authors to use. Two journals mentioned that the possible effects of publication on subjects should be considered. Many journal consent forms mentioned the difficulties in ensuring complete anonymity of subjects, but few addressed the study objective, the subjects' right to refuse consent and the withdrawal of consent. The main reason for requiring the submission of consent forms was to confirm that consent had been obtained.ConclusionApproximately 40% of journals required subject consent to be obtained. However, differences were observed depending on the fields. Specific considerations were not always documented. There is a need to address issues around the study objective, subjects' right to refuse consent and the withdrawal of consent. Whether responsibility for ensuring that the consent form has been signed lies with publishers also needs to be discussed.

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Issues in identifying germ tube positive yeasts by conventional methods.

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Issues in identifying germ tube positive yeasts by conventional methods.

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