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Foods (Basel, Switzerland) Oct 2021Yeast can be isolated from tofu wastewater and the cell wall in the form of β-glucan can act as a natural decontaminant agent. This study aimed to isolate and...
Yeast can be isolated from tofu wastewater and the cell wall in the form of β-glucan can act as a natural decontaminant agent. This study aimed to isolate and characterize native yeast from tofu wastewater, which can be extracted to obtain β-glucan and then identify the yeast and its β-glucan activity regarding antifungal ability against and aflatoxin-reducing activity towards aflatoxin B1 (AFB1) and B2 (AFB2). Tofu wastewater native yeast was molecularly identified, and the growth observed based on optical density for 96 h and the pH also measured. β-glucan was extracted from native yeast cell walls with the acid-base method and then the inhibition activity towards was tested using the well diffusion method and microscopic observation. AFB1 and AFB2 reduction were identified using HPLC LC-MS/MS. The results showed that the native yeast isolated was with a β-glucan yield of 6.59%. and its β-glucan showed an inhibition zone against of 11.33 ± 4.93 and 7.33 ± 3.51 mm, respectively. Total aflatoxin-reducing activity was also shown by of 26.85 ± 2.87%, and β-glucan of 27.30 ± 1.49%, while AFB1- and AFB2-reducing activity by was 36.97 ± 3.07% and 27.13 ± 1.69%, and β-glucan was 27.13 ± 1.69% and 32.59 ± 4.20%, respectively.
PubMed: 34828900
DOI: 10.3390/foods10112619 -
Journal of Clinical Microbiology May 2015Candida inconspicua and Candida (Pichia) norvegensis are two emerging pathogenic species that exhibit reduced susceptibility to azole derivatives. Conventional...
Candida inconspicua and Candida (Pichia) norvegensis are two emerging pathogenic species that exhibit reduced susceptibility to azole derivatives. Conventional (biochemical) approaches do not readily differentiate between the two species. The first aim of this work was to analyze the performance of biochemical, proteomic (matrix-assisted laser desorption ionization-time of flight [MALDI-TOF]), and molecular approaches in the precise identification of these species. These results then led us to sequence 3 genomic loci, i.e., the internal transcribed spacer (ITS) region of the ribosomal DNA (rDNA), the D1/D2 domain of the 28S rDNA, and the elongation factor 1α (EF-1α) gene, either directly or following cloning, of 13 clinical isolates and 9 reference strains belonging to the 5 species included in the Pichia cactophila clade, namely, Pichia cactophila, Pichia insulana, C. inconspicua, C. norvegensis, and P. pseudocactophila. Finally, isolates of C. inconspicua were challenged for sexual reproduction on the appropriate medium. Our results show that EF-1α sequencing and proteic profiling by MALDI-TOF are the two most efficient approaches to distinguish between C. norvegensis and C. inconspicua. As a characteristic of the P. cactophila clade, we found multiple alleles of the rDNA regions in certain strains belonging to the tested species, making ITS or D1/D2 sequencing not appropriate for identification. Whatever the method of identification, including MALDI-TOF and EF-1α sequencing, none could differentiate C. inconspicua from P. cactophila. The results of phylogenetic analysis and the generation of asci from pure cultures of all C. inconspicua strains both support the identification of P. cactophila as the teleomorph of C. inconspicua.
Topics: Candida; Candidiasis; Cluster Analysis; Crosses, Genetic; DNA, Fungal; DNA, Ribosomal; DNA, Ribosomal Spacer; Gene Order; Humans; Molecular Sequence Data; Mycological Typing Techniques; Peptide Elongation Factor 1; Phylogeny; Proteome; RNA, Ribosomal, 28S; Sequence Analysis, DNA; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
PubMed: 25762773
DOI: 10.1128/JCM.02913-14 -
Microorganisms Sep 2022The use of yeasts as starter cultures was boosted with the emergence of large-scale fermentations in the 20th century. Since then, has been the most common and widely... (Review)
Review
The use of yeasts as starter cultures was boosted with the emergence of large-scale fermentations in the 20th century. Since then, has been the most common and widely used microorganism in the food industry. However, species have also been used as an adjuvant in cheese production or as starters for coffee, cocoa, vegetable, meat, beer, and wine fermentations. A thorough screening of candidate is sometimes performed to obtain the best performing strains to enhance specific features. Some commonly selected species include (teleomorph ) (wine), (teleomorph ) (coffee), (teleomorph ) (cheese), and (teleomorph ) and (teleomorph ) (cocoa). These species are associated with the production of key metabolites (food aroma formation) and different enzymes. However, safety-associated selection criteria are often neglected. It is widely known that some species are opportunistic human pathogens, with important clinical relevance. Here, the physiology and metabolism of species are addressed, initially emphasizing their clinical aspects and potential pathogenicity. Then, species used in food fermentations and their functional roles are reported. We recommended that not be used as food cultures if safety assessments are not performed. Some safety features are highlighted to help researchers choose methods and selection criteria.
PubMed: 36144457
DOI: 10.3390/microorganisms10091855 -
FEBS Letters Apr 2022Flavohaemoglobins (FlavoHbs) function as nitric oxide dioxygenases, oxidizing nitric oxide with nitrite and shuttling electrons from NAD(P)H via FAD and O . Here, using...
Flavohaemoglobins (FlavoHbs) function as nitric oxide dioxygenases, oxidizing nitric oxide with nitrite and shuttling electrons from NAD(P)H via FAD and O . Here, using pulse radiolysis, we investigate intramolecular electron transfer between FAD and haem b in FlavoHbs. We found that reduction of FlavoHb with hydrated electrons proceeded via two phases: an initial fast phase and a second slower process. Absorbance measured at 600 nm revealed fast flavin reduction followed by a slower decrease corresponding to reoxidation of FAD. The slower process was partially lost in FlavoHbs lacking FAD. These results suggest that the slower phase is attributable to intramolecular electron transfer from FAD to the haem iron. The rate constant in the absence of azole compound (3.3 × 10 s ) was accelerated ~ 10-fold (2.7 × 10 s ) by the binding of econazole, reflecting a conformational change in the open-to-closed transition.
Topics: Anti-Bacterial Agents; Azoles; Candida; Electron Transport; Electrons; Flavin-Adenine Dinucleotide; Heme; Kinetics; NAD; Nitric Oxide; Oxidation-Reduction; Pichia
PubMed: 35253217
DOI: 10.1002/1873-3468.14327 -
Infection and Drug Resistance 2021To investigate the colonization and susceptibility to antifungal drugs of oral yeasts in head and neck cancer patients in Hainan, China.
PURPOSE
To investigate the colonization and susceptibility to antifungal drugs of oral yeasts in head and neck cancer patients in Hainan, China.
METHODS
Oral mucosa samples from 211 head and neck cancer patients were collected. Oral yeasts were isolated and identified to species by rDNA ITS sequencing. The susceptibilities of all yeasts to amphotericin B, fluconazole, fluorocytosine, itraconazole, and ketoconazole were determined.
RESULTS
Yeasts were isolated from 124 of the 211 oral swabs. The 124 yeast isolates were classified into following 10 species, from the most frequent to the least frequent, (53.2%), (22.6%), (6.5%), (5.6%), (4.8%), (2.4%), (1.6%), (1.6%), (0.8%), and (0.8%). The overall frequencies of resistance among the yeasts to amphotericin B, fluconazole, flucytosine, itraconazole, and ketoconazole were 4.8%, 8.1%, 16.1%, 9.7%, and 9.7%, respectively. One strain and one strain were tolerant/resistant to all five drugs.
CONCLUSION
Given the high prevalence of oral yeast colonization in head and neck cancer patients and the observed resistance of certain yeast isolates to the five antifungal drugs, our results suggest that rapid identification and susceptibility testing should be implemented before antifungal treatment is applied among patients with head and neck cancer in Hainan.
PubMed: 34168468
DOI: 10.2147/IDR.S316368 -
BMC Infectious Diseases Feb 2015Genetic variation in the ribosomal DNA (rDNA) internal transcribed spacer (ITS) region has been studied among fungi. However, the numbers of ITS sequence polymorphisms...
BACKGROUND
Genetic variation in the ribosomal DNA (rDNA) internal transcribed spacer (ITS) region has been studied among fungi. However, the numbers of ITS sequence polymorphisms in the various Candida species and their associations with sources of invasive fungal infections remain poorly investigated. Here, we characterized the intraspecific and interspecific ITS diversity of Candida spp. strains collected from patients with bloodstream or oroesophageal candidiasis.
METHODS
We selected cultures of representative medically important species of Candida as well as some rare and emerging pathogens. Identification was performed by micromorphology and by biochemical testing using an ID32C system, as well as by the sequencing of rDNA ITS. The presence of intraspecific ITS polymorphisms was characterized based on haplotype networks, and interspecific diversity was characterized based on Bayesian phylogenetic analysis.
RESULTS
Among 300 Candida strains, we identified 76 C. albicans, 14 C. dubliniensis, 40 C. tropicalis, 47 C. glabrata, 34 C. parapsilosis (sensu stricto), 31 C. orthopsilosis, 3 C. metapsilosis, 21 Meyerozyma guilliermondii (C. guilliermondii), 12 Pichia kudriavzevii (C. krusei), 6 Clavispora lusitaniae (C. lusitaniae), 3 C. intermedia, 6 Wickerhamomyces anomalus (C. pelliculosa), and 2 C. haemulonii strains, and 1 C. duobushaemulonii, 1 Kluyveromyces marxianus (C. kefyr), 1 Meyerozyma caribbica (C. fermentati), 1 Pichia norvegensis (C. norvegensis), and 1 Lodderomyces elongisporus strain. Out of a total of seven isolates with inconsistent ID32C profiles, ITS sequencing identified one C. lusitaniae strain, three C. intermedia strains, two C. haemulonii strains and one C. duobushaemulonii strain. Analysis of ITS variability revealed a greater number of haplotypes among C. albicans, C. tropicalis, C. glabrata and C. lusitaniae, which are predominantly related to endogenous sources of acquisition. Bayesian analysis confirmed the major phylogenetic relationships among the isolates and the molecular identification of the different Candida spp.
CONCLUSIONS
Molecular studies based on ITS sequencing are necessary to identify closely related and emerging species. Polymorphism analysis of the ITS rDNA region demonstrated its utility as a genetic marker for species identification and phylogenetic relationships as well as for drawing inferences concerning the natural history of hematogenous infections caused by medically important and emerging Candida species.
Topics: Candida; Candidiasis, Invasive; Communicable Diseases, Emerging; Cross Infection; DNA Mutational Analysis; DNA, Ribosomal Spacer; Genetic Variation; Humans; Phylogeny; Polymorphism, Genetic
PubMed: 25887032
DOI: 10.1186/s12879-015-0793-3 -
Tropical Biomedicine Aug 2011The biodiversity and the killer activity of yeasts isolated from various types of fermented food in Malaysia were investigated in this study. Of 252 yeasts isolated from...
The biodiversity and the killer activity of yeasts isolated from various types of fermented food in Malaysia were investigated in this study. Of 252 yeasts isolated from 48 fermented food samples in this study, 19 yeast species were identified based on sequence analysis of the ITS1-5.8S-ITS2 partial fragments of the yeasts. A total of 29 (11.5%) of the yeast isolates demonstrated killer activity to at least one Candida species tested in this study; including 22 isolates of Trichosporon asahii, 4 isolates of Pichia anomala, and one isolate each of Pichia norvegensis, Pichia fermentans and Issatchenkia orientalis, respectively. The presence of killer yeasts reflects antagonism that occurs during microbial interaction in the fermented food, whereby certain yeasts produce killer toxins and possibly other toxic substances in competition for limited nutrients and space. The anti-Candida activity demonstrated by killer yeasts in this study should be further explored for development of alternative therapy against candidiasis.
Topics: Antibiosis; DNA, Fungal; DNA, Ribosomal; DNA, Ribosomal Spacer; Food Microbiology; Genes, rRNA; Malaysia; RNA, Fungal; RNA, Ribosomal, 5.8S; Sequence Analysis, DNA; Yeasts
PubMed: 22041766
DOI: No ID Found -
The Journal of Molecular Diagnostics :... Jan 2011Recent changes in the epidemiology of candidiasis highlighted an increase in non- Candida albicans species emphasizing the need for reliable identification methods....
Recent changes in the epidemiology of candidiasis highlighted an increase in non- Candida albicans species emphasizing the need for reliable identification methods. Molecular diagnostics in fungal infections may improve species characterization, particularly in cases of the closely related species in the Candida complexes. We developed two PCR/restriction fragment length polymorphism assays, targeting either a part of the intergenic spacer 2 or the entire intergenic spacer (IGS) of ribosomal DNA using a panel of 270 isolates. A part of the intergenic spacer was used for discrimination between C. albicans and C. dubliniensis and between species of the C. glabrata complex (C. glabrata/C. bracarensis/C. nivariensis). The whole IGS was applied to C. parapsilosis, C. metapsilosis, and C. orthopsilosis, and to separate C. famata (Debaryomyces hansenii) from C. guilliermondii (Pichia guilliermondii) and from the other species within this complex (ie, C. carpophila, C. fermentati and C. xestobii). Sharing similar biochemical patterns, Pichia norvegensis and C. inconspicua exhibited specific IGS profiles. Our study confirmed that isolates of C. guilliermondii were frequently mis-identified as C. famata. As much as 67% of the clinical isolates phenotypically determined as C. famata were recognized mostly as true P. guilliermondii. Conversely, 44% of the isolates initially identified as C. guilliermondii were corrected by the IGS fingerprints as C. parapsilosis, C. fermentati, or C. zeylanoides. These two PCR/restriction fragment length polymorphism methods may be used as reference tools [either alternatively or adjunctively to the existing ribosomal DNA (26S or ITS) sequence comparisons] for unambiguous determination of the Candida species for which phenotypic characterization remains problematic.
Topics: Candida; Candidiasis; DNA Fingerprinting; DNA, Ribosomal Spacer; Genes, Fungal; Humans; Mycological Typing Techniques; Phylogeny; Polymorphism, Restriction Fragment Length
PubMed: 21227390
DOI: 10.1016/j.jmoldx.2010.11.014