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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 -
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 -
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 -
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