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Molecular genetic diversity of the Saccharomyces yeasts in Taiwan: Saccharomyces arboricola, Saccharomyces cerevisiae and Saccharomyces kudriavzevii

Naumov GI, Lee CF, Naumova ES

Antonie Van Leeuwenhoek, 2013 Jan;103(1):217-28.
PMID: 22941248 DOI: 10.1007/s10482-012-9803-2

Genetic hybridization, sequence and karyotypic analyses of natural Saccharomyces yeasts isolated in different regions of Taiwan revealed three biological species: Saccharomyces arboricola, Saccharomyces cerevisiae and Saccharomyces kudriavzevii. Intraspecies variability of the D1/D2 and ITS1 rDNA sequences was detected among S. cerevisiae and S. kudriavzevii isolates. According to molecular and genetic analyses, the cosmopolitan species S. cerevisiae and S. kudriavzevii contain local divergent populations in Taiwan, Malaysia and Japan. Six of the seven known Saccharomyces species are documented in East Asia: S. arboricola, S. bayanus, S. cerevisiae, S. kudriavzevii, S. mikatae, and S. paradoxus.

Matched MeSH terms: DNA, Fungal/genetics
Molecular diversity of fungal endophytes isolated from Garcinia mangostana and Garcinia parvifolia

Sim JH, Khoo CH, Lee LH, Cheah YK

J Microbiol Biotechnol, 2010 Apr;20(4):651-8.
PMID: 20467234

Garcinia is commonly found in Malaysia, but limited information is available regarding endophytic fungi associated with this plant. In this study, 24 endophytic fungi were successfully recovered from different parts of two Garcinia species. Characterization of endophytic fungi was performed based on the conserved internal transcribed spacer (ITS) region sequence analysis and the antimicrobial properties. Results revealed that fruits of the plant appeared to be the highest inhabitation site (38 %) as compared with others. Glomerella sp., Guignardia sp., and Phomopsis sp. appeared to be the predominant endophytic fungi group in Garcinia mangostana and Garcinia parvifolia. Phylogenetic relationships of the isolated endophytic fungi were estimated from the sequences of the ITS region. On the other hand, antibacterial screening showed 11 of the isolates possessed positive response towards pathogenic and nonpathogenic bacteria. However, there was no direct association between certain antibacterial properties with the specific genus observed.

Matched MeSH terms: DNA, Fungal/genetics
Molecular differentiation and antifungal susceptibilities of Candida parapsilosis isolated from patients with bloodstream infections

Tay ST, Na SL, Chong J

J Med Microbiol, 2009 Feb;58(Pt 2):185-191.
PMID: 19141735 DOI: 10.1099/jmm.0.004242-0

The genetic heterogeneity and antifungal susceptibility patterns of Candida parapsilosis isolated from blood cultures of patients were investigated in this study. Randomly amplified polymorphic DNA (RAPD) analysis generated 5 unique profiles from 42 isolates. Based on the major DNA fragments of the RAPD profiles, the isolates were identified as RAPD type P1 (29 isolates), P2 (6 isolates), P3 (4 isolates), P4 (2 isolates) and P5 (1 isolate). Sequence analysis of the internal transcribed spacer (ITS) gene of the isolates identified RAPD type P1 as C. parapsilosis, P2 and P3 as Candida orthopsilosis, P4 as Candida metapsilosis, and P5 as Lodderomyces elongisporus. Nucleotide variations in ITS gene sequences of C. orthopsilosis and C. metapsilosis were detected. Antifungal susceptibility testing using Etests showed that all isolates tested in this study were susceptible to amphotericin B, fluconazole, ketoconazole, itraconazole and voriconazole. C. parapsilosis isolates exhibited higher MIC(50) values than those of C. orthopsilosis for all of the drugs tested in this study; however, no significant difference in the MICs for these two Candida species was observed. The fact that C. orthopsilosis and C. metapsilosis were responsible for 23.8 and 4.8 % of the cases attributed to C. parapsilosis bloodstream infections, respectively, indicates the clinical relevance of these newly described yeasts. Further investigations of the ecological niche, mode of transmission and virulence of these species are thus essential.

Matched MeSH terms: DNA, Fungal/genetics
Molecular classification and phylogenetic relationships of selected edible Basidiomycetes species

Avin FA, Bhassu S, Shin TY, Sabaratnam V

Mol Biol Rep, 2012 Jul;39(7):7355-64.
PMID: 22327649 DOI: 10.1007/s11033-012-1567-2

Morphological identification of edible mushrooms can sometimes prove troublesome, because phenotypic variation in fungi can be affected by substrate and environmental factors. One of the most important problems for mushroom breeders is the lack of a systematic consensus tool to distinguish different species, which are sometimes morphologically identical. Basidiomycetes as one of the largest groups of edible mushrooms have become more important in recent times for their medicinal and nutritional properties. Partial rDNA sequences, including the Internal Transcribed Spacer I-5.8SrDNA-Internal Transcribed Spacer II, were used in this study for molecular identification and assessment of phylogenetic relationships between selected edible species of the Basidiomycetes. Phylogenetic trees showed five distinct clades; each clade belonging to a separate family group. The first clade included all the species belonging to the Pleurotaceae (Pleurotus spp.) family; similarly, the second, third, fourth, and fifth clades consist of species from the Agaricaceae (Agaricus sp.), Lyophllaceae (Hypsigygus sp.), Marasmiaceae (Lentinula edodes sp.) and Physalacriaceae (Flammulina velutipes sp.) families, respectively. Moreover, different species of each family were clearly placed in a distinct sub-cluster and a total of 13 species were taken for analysis. Species differentiation was re-confirmed by AMOVA analysis (among the populations: 99.67%; within: 0.33%), nucleotide divergence, haplotyping and P value. Polymorphism occurred throughout the ITS regions due to insertion-deletion and point mutations, and can be clearly differentiated within the families as well as genera. Moreover, this study proves that the sequence of the ITS region is a superior molecular DNA barcode for taxonomic identification of Basidiomycetes.

Matched MeSH terms: DNA, Fungal/genetics*
Fulltext Molecular Diagnosis of Microsporidia among Immunocompromised Patients in Kuala Lumpur, Malaysia

Hassan NA, Lim YAL, Mahmud R, Mohd-Shaharuddin N, Wan Sulaiman WY, Ngui R

Am J Trop Med Hyg, 2018 Dec;99(6):1562-1566.
PMID: 30382015 DOI: 10.4269/ajtmh.17-0901

Microsporidia are obligate intracellular parasitic fungi causing chronic diarrhea, particularly among immunocompromised patients. The current method used for diagnosis is based on conventional microscopy, which does not differentiate parasites at the species level. The present study was carried out to identify microsporidian species in immunocompromised patients. From March 2016 to March 2017, a total of 289 archived stool samples were examined microscopically for microsporidian spores using Gram-chromotrope Kinyoun (GCK) stain. Positive stool samples by microscopy were subjected to polymerase chain reaction and sequencing for species identification. Based on microscopy examination, the overall prevalence of microsporidian infections was 32.2% (93/289; 95% CI = 27.1-37.8). Of these stool samples, 45 samples were successfully amplified and confirmed as Enterocytozoon bieneusi. No Encephalitozoon intestinalis was detected. Accurate identification of species might help clinicians to decide appropriate management strategies as dissemination risks and treatment response vary for different species, hence improving the management of microsporidian infections.

Matched MeSH terms: DNA, Fungal/genetics*
Locally isolated yeasts from Malaysia: identification, phylogenetic study and characterization

Oslan SN, Salleh AB, Rahman RN, Basri M, Chor AL

Acta Biochim. Pol., 2012;59(2):225-9.
PMID: 22577620

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.

Matched MeSH terms: DNA, Fungal/genetics
Kodamaea transpacifica f.a., sp. nov., a yeast species isolated from ephemeral flowers and insects in the Galapagos Islands and Malaysia: further evidence for ancient human transpacific contacts

Freitas LFD, Barriga EJC, Barahona PP, Lachance MA, Rosa CA

Int J Syst Evol Microbiol, 2013 Nov;63(Pt 11):4324-4329.
PMID: 24014626 DOI: 10.1099/ijs.0.052282-0

Twenty-four yeast strains were isolated from ephemeral flowers of Ipomoea spp. and Datura sp. and their associated insects in the Galápagos Archipelago, Ecuador, and from Ipomoea spp. and associated insects in the Cameron Highlands, Malaysia. Sequences of the D1/D2 domains of the large subunit rRNA gene indicated that these strains belong to a novel yeast species of the Kodamaea clade, although the formation of ascospores was not observed. The closest relative is Candida restingae. The human-mediated dispersion of this species by transpacific contacts in ancient times is suggested. The name Kodamaea transpacifica f.a., sp. nov. is proposed to accommodate these isolates. The type strain is CLQCA-24i-070(T) ( = CBS 12823(T) = NCYC 3852(T)); MycoBank number MB 803609.

Matched MeSH terms: DNA, Fungal/genetics
Fulltext Issues in identifying germ tube positive yeasts by conventional methods

Yazdanpanah A, Khaithir TM

J Clin Lab Anal, 2014 Jan;28(1):1-9.
PMID: 24375729 DOI: 10.1002/jcla.21635

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.

Matched MeSH terms: DNA, Fungal/genetics
Isolation and characterization of an acrylamide-degrading yeast Rhodotorula sp. strain MBH23 KCTC 11960BP

Rahim MB, Syed MA, Shukor MY

J Basic Microbiol, 2012 Oct;52(5):573-81.
PMID: 22144174 DOI: 10.1002/jobm.201100116

As well as for chemical and environmental reasons, acrylamide is widely used in many industrial applications. Due to its carcinogenicity and toxicity, its discharge into the environment causes adverse effects on humans and ecology alike. In this study, a novel acrylamide-degrading yeast has been isolated. The isolate was identified as Rhodotorula sp. strain MBH23 using ITS rRNA analysis. The results showed that the best carbon source for growth was glucose at 1.0% (w/v). The optimum acrylamide concentration, being a nitrogen source for cellular growth, was at 500 mg l(-1). The highest tolerable concentration of acrylamide was 1500 mg l(-1) whereas growth was completely inhibited at 2000 mg l(-1). At 500 mg l(-1), the strain MBH completely degraded acrylamide on day 5. Acrylic acid as a metabolite was detected in the media. Strain MBH23 grew well between pH 6.0 and 8.0 and between 27 and 30 °C. Amides such as 2-chloroacetamide, methacrylamide, nicotinamide, acrylamide, acetamide, and propionamide supported growth. Toxic heavy metals such as mercury, chromium, and cadmium inhibited growth on acrylamide.

Matched MeSH terms: DNA, Fungal/genetics
Isolation and characterisation of a partial peptide synthetase gene from Trichoderma asperellum

Chutrakul C, Peberdy JF

FEMS Microbiol Lett, 2005 Nov 15;252(2):257-65.
PMID: 16214297

Many species of Trichoderma have attracted interest as agents for the biological control of soil borne fungal pathogens of a range of crop plants. Research on the biochemical mechanisms associated with this application has focused on the ability of these fungi to produce enzymes which lyse fungal cell walls, and antifungal antibiotics. An important group of the latter are the non-ribosomal peptides called peptaibols. In this study Trichoderma asperellum, a strain used in biological control in Malaysia, was found to produce the peptaibol, trichotoxin. This type of peptide molecule is synthesised by a peptide synthetase (PES) enzyme template encoded by a peptide synthetase (pes) gene. Using nucleotide sequences amplified from adenylation (A-) domains as probes, to hybridise against a lambda FIXII genomic library from T. asperellum, 25 clones were recovered. These were subsequently identified as representative of four groups based on their encoding properties for specific amino acid incorporation modules in a PES. This was based on analysis of their amino acid sequences which showed up to 86% identity to other PESs including TEX 1.

Matched MeSH terms: DNA, Fungal/genetics
Fulltext Isolation and Characterization of an Atypical Metschnikowia sp. Strain from the Skin Scraping of a Dermatitis Patient

Kuan CS, Ismail R, Kwan Z, Yew SM, Yeo SK, Chan CL, et al.

PLoS One, 2016;11(6):e0156119.
PMID: 27280438 DOI: 10.1371/journal.pone.0156119

A yeast-like organism was isolated from the skin scraping sample of a stasis dermatitis patient in the Mycology Unit Department of Medical Microbiology, University Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia. The isolate produced no pigment and was not identifiable using chromogenic agar and API 20C AUX. The fungus was identified as Metschnikowia sp. strain UM 1034, which is close to that of Metschnikowia drosophilae based on ITS- and D1/D2 domain-based phylogenetic analysis. However, the physiology of the strain was not associated to M. drosophilae. This pathogen exhibited low sensitivity to all tested azoles, echinocandins, 5-flucytosine and amphotericin B. This study provided insight into Metschnikowia sp. strain UM 1034 phenotype profiles using a Biolog phenotypic microarray (PM). The isolate utilized 373 nutrients of 760 nutrient sources and could adapt to a broad range of osmotic and pH environments. To our knowledge, this is the first report of the isolation of Metschnikowia non-pulcherrima sp. from skin scraping, revealing this rare yeast species as a potential human pathogen that may be misidentified as Candida sp. using conventional methods. Metschnikowia sp. strain UM 1034 can survive in flexible and diverse environments with a generalist lifestyle.

Matched MeSH terms: DNA, Fungal/genetics
Isolates of the emerging pathogen Candida auris present in the UK have several geographic origins

Borman AM, Szekely A, Johnson EM

Med Mycol, 2017 Jul 01;55(5):563-567.
PMID: 28204557 DOI: 10.1093/mmy/myw147

Candida auris has recently emerged as a serious nosocomial health risk, with widespread outbreaks in numerous hospitals worldwide and the existence of geographic region-specific discrete clonal lineages. Here we have compared the rDNA sequences of 24 isolates of Candida auris from 14 different hospital centers in the United Kingdom with those of strains from different international origins present in the public sequence databases. Here we show that UK isolates of C. auris fall into three well-supported clades corresponding to lineages that have previously been reported from India, Malaysia and Kuwait, Japan and Korea, and South Africa, respectively.

Matched MeSH terms: DNA, Fungal/genetics
Identification of Botryosphaeriaceae associated with stem-end rot of mango (Mangifera indica L.) in Malaysia

Li L, Mohd MH, Mohamed Nor NMI, Subramaniam S, Latiffah Z

J Appl Microbiol, 2021 Apr;130(4):1273-1284.
PMID: 32813902 DOI: 10.1111/jam.14828

AIMS: To identify Botryosphaeriaceae fungal species that are associated with stem-end rot of mango, and to study their pathogenicity on mango fruit.
METHODS AND RESULTS: Based on the sequences of internal transcribed spacer (ITS), TEF1-α and β-tubulin, as well as on the phylogenetic analysis of combined sequences, four species of Lasiodiplodia (L. theobromae,L. pseudotheobromae, L. iranensis, L. mahajangana) and two species of Neofusicoccum (N. ribis, N. parvum) were identified. Pseudofusicoccum violaceum, Neoscytalidium dimidiatum and three species of Botryosphaeria (B. scharifii, B. dothidea, B. ramosa) were identified based on sequences of ITS and TEF1-α. Pathogenicity test of selected isolates were tested on Chok Anan, Waterlily and Falan mango cultivars. Generally, all species were observed to be pathogenic on the three tested mango cultivars on wounded fruits, except for N. ribis and N. parvum, which were pathogenic on both wounded and unwounded fruits. However, N. ribis was only pathogenic on cultivar Falan, whereas B. ramosa were pathogenic on cultivars Waterlily and Falan.
CONCLUSIONS: Eleven species of Botryosphaeriaceae were associated with mango stem-end rot in Malaysia. To the best of our knowledge, four species, namely L. mahajangana, B. ramosa, N. ribis and P. violaceum are the first recorded Botryosphaeriaceae fungi associated with stem end rot of mango.
SIGNIFICANCE AND IMPACT OF THE STUDY: The identification of Botryosphaeriaceae fungi is important to establish suitable control measures and quarantine requirements. Many species have a wide host range, which means that there is a possibility of cross infection from other infected plants.

Matched MeSH terms: DNA, Fungal/genetics
Fulltext Identification and Characterization of a Rare Fungus, Quambalaria cyanescens, Isolated from the Peritoneal Fluid of a Patient after Nocturnal Intermittent Peritoneal Dialysis

Kuan CS, Yew SM, Toh YF, Chan CL, Lim SK, Lee KW, et al.

PLoS One, 2015;10(12):e0145932.
PMID: 26716988 DOI: 10.1371/journal.pone.0145932

Peritonitis is the leading complication of peritoneal dialysis, which is primarily caused by bacteria rather than fungi. Peritonitis is responsible for approximately 18% of the infection-related mortality in peritoneal dialysis patients. In this paper, we report the isolation of a rare fungus, Quambalaria cyanescens, from the peritoneal fluid of a man after he switched from continuous ambulatory peritoneal dialysis to nocturnal intermittent peritoneal dialysis. Based on the morphological examination and multigene phylogeny, the clinical isolate was confirmed as Q. cyanescens. This pathogen exhibited low sensitivity to all tested echinocandins and 5-flucytosine. Interestingly, morphological characterization revealed that Q. cyanescens UM 1095 produced different pigments at low temperatures (25°C and 30°C) on various culture media. It is important to monitor the emergence of this rare fungus as a potential human pathogen in the tropics. This study provides insight into Q. cyanescens UM 1095 phenotype profiles using a Biolog phenotypic microarray (PM). Of the 760 nutrient sources tested, Q. cyanescens UM 1095 utilized 42 compounds, and the fungus can adapt to a broad range of osmotic and acidic environments. To our knowledge, this is the first report of the isolation of Q. cyanescens from peritoneal fluid, revealing this rare fungus as a potential human pathogen that may be misidentified using conventional methods. The detailed morphological, molecular and phenotypic characterization of Q. cyanescens UM 1095 provides the basis for future studies on its biology, lifestyle, and potential pathogenicity.

Matched MeSH terms: DNA, Fungal/genetics
Fulltext Genome sequence of an unclassified pleosporales species isolated from human nasopharyngeal aspirate

Ng KP, Yew SM, Chan CL, Soo-Hoo TS, Na SL, Hassan H, et al.

Eukaryotic Cell, 2012 Jun;11(6):828.
PMID: 22645233 DOI: 10.1128/EC.00133-12

Pleosporales is the largest order in the fungal class Dothideomycetes. We report the 36,814,818-bp draft genome sequence and gene annotation of UM1110, a Pleosporales isolate associated with unclassified genera that is potentially a new fungal species. Analysis of the genome sequence led to the finding of genes associated with fungal adhesive proteins, secreted proteases, allergens, and pseudohyphal development.

Matched MeSH terms: DNA, Fungal/genetics
Four new bioluminescent taxa of Mycena sect. Calodontes from Peninsular Malaysia

Chew AL, Tan YS, Desjardin DE, Musa MY, Sabaratnam V

Mycologia, 2014 Sep-Oct;106(5):976-88.
PMID: 24891424 DOI: 10.3852/13-274

Three new species and one new variety of bioluminescent Mycena collected from Peninsular Malaysia are described herein. All new species belong to Mycena sect. Calodontes in what is known as the Mycena pura complex. Comprehensive descriptions, photographs, illustrations and comparisons with phenetically similar species are provided. Molecular sequences data from the nuclear internal transcribed spacers (ITS-1 and ITS-2, including the 5.8S rRNA) were used to infer relationships within sect. Calodontes. Axenic cultures were obtained to provide data on culture morphology. This is the first published photographic documentation of bioluminescent basidiomes of members of Mycena sect. Calodontes. Also, this addition brings the total known bioluminescent fungi to 77 species.

Matched MeSH terms: DNA, Fungal/genetics
Fulltext First Two Cases of Fungal Infections Associated with Multi-drug Resistant Yeast, Fereydounia khargensis

Tap RM, Ramli NY, Sabaratnam P, Hashim R, Bakri AR, Bee LB, et al.

Mycopathologia, 2016 Aug;181(7-8):531-7.
PMID: 27010640 DOI: 10.1007/s11046-016-0002-y

The number of new fungal pathogens is increasing due to growing population of immunocompromised patients and advanced identification techniques. Fereydounia khargensis is a yeast and was first described in 2014 from environmental samples. As far as we know, this is the first report of human infections associated with F. khargensis. The yeasts were isolated from blood of a HIV-positive patient and pleural fluid of chronic renal failure patient. Amplification and sequencing of the internal transcribed spacer and the large subunit regions confirmed the identity of the isolates. Both isolates showed multi-drug resistance to antifungal agents tested.

Matched MeSH terms: DNA, Fungal/genetics
Fulltext Evolution of mycoheterotrophy in Polygalaceae: The case of Epirixanthes

Mennes CB, Moerland MS, Rath M, Smets EF, Merckx VS

Am J Bot, 2015 Apr;102(4):598-608.
PMID: 25878092 DOI: 10.3732/ajb.1400549

The mycoheterotrophic lifestyle has enabled some plant lineages to obtain carbon from their mycorrhizal symbionts. The mycoheterotrophic genus Epirixanthes (Polygalaceae) consists of six species from tropical Asia. Although it is probably closely related to the chlorophyllous genus Salomonia and linked to arbuscular mycorrhizal fungi, lack of DNA sequence data has thus far prevented these hypotheses from being tested. Therefore, the evolutionary history of Epirixanthes remains largely unknown.

Matched MeSH terms: DNA, Fungal/genetics
Evidence for a general-purpose genotype in Candida albicans, highly prevalent in multiple geographical regions, patient types and types of infection

Schmid J, Herd S, Hunter PR, Cannon RD, Yasin MSM, Samad S, et al.

Microbiology (Reading), 1999 Sep;145 ( Pt 9):2405-2413.
PMID: 10517593 DOI: 10.1099/00221287-145-9-2405

Epidemiological studies, using the probe Ca3, have shown that in a given patient population a single cluster of genetically related Candida albicans isolates usually predominates. The authors have investigated whether these local clusters are part of a single group, geographically widespread and highly prevalent as an aetiological agent of various types of candidiasis. An unrooted neighbour-joining tree of 266 infection-causing C. albicans isolates (each from a different individual) from 12 geographical regions in 6 countries was created, based on genetic distances generated by Ca3 fingerprinting. Thirty-seven per cent of all isolates formed a single genetically homogeneous cluster (cluster A). The remainder of isolates were genetically diverse. Using the maximum branch length within cluster A as a cut-off, they could be divided into 37 groups, whose prevalence ranged between 0.3% and 9%. Strains from cluster A were highly prevalent in all but one geographical region, with a mean prevalence across all regions of 41%. When isolates were separated into groups based on patient characteristics or type of infection, strains from cluster A had a prevalence exceeding 27% in each group, and their mean prevalence was 43% across all patient characteristics. These data provide evidence that cluster A constitutes a general-purpose genotype, which is geographically widespread and acts as a predominant aetiological agent of all forms of candidiasis in all categories of patients surveyed.

Matched MeSH terms: DNA, Fungal/genetics
Electrochemical DNA biosensor for the detection of specific gene related to Trichoderma harzianum species

Siddiquee S, Yusof NA, Salleh AB, Abu Bakar F, Heng LY

Bioelectrochemistry, 2010 Aug;79(1):31-6.
PMID: 19945357 DOI: 10.1016/j.bioelechem.2009.10.004

A new electrochemical biosensor is described for voltammetric detection of gene sequence related to Trichoderma harzianum. The sensor involves immobilization of a 20 base single-stranded probe (ssDNA), which is complementary to a specific gene sequence related to T. harzianum on a gold electrode through specific adsorption. The DNA probe was used to determine the amount of target gene in solution using methylene blue (MB) as the electrochemical indicator. The covalently immobilized probe could selectively hybridize with the target DNA to form a hybrid on the surface despite the bases being attached to the electrode. The changes in the peak currents of methylene blue (MB), an electroactive label, were observed upon hybridization of probe with the target. Peak currents were found to increase in the following order: hybrid-modified AuE and the probe-modified AuE which localized to the affinity of MB. Control experiments with the non-complementary oligonucleotides were performed to assess whether the DNA biosensor responds selectively, via hybridization, to the target. DNA biosensor also able to detect microorganism at the species levels without nucleic acid amplification. The redox current was linearly related to the concentration of target oligonucleotide DNA, ranged from 1-20 ppm. Numerous factors, affecting the probe immobilization, target hybridization and indicator binding reactions are optimized to maximize the sensitivity and reduce the assay time.

Matched MeSH terms: DNA, Fungal/genetics

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