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Food Microbiology Aug 2023Contamination of white-brined cheeses (WBCs) with yeasts is of major concern in the dairy industry. This study aimed to identify yeast contaminants and characterize...
Contamination of white-brined cheeses (WBCs) with yeasts is of major concern in the dairy industry. This study aimed to identify yeast contaminants and characterize their succession in white-brined cheese during a shelf-life of 52 weeks. White-brined cheeses added herbs (WBC1) or sundried tomatoes (WBC2) were produced at a Danish dairy and incubated at 5 °C and 10 °C. An increase in yeast counts was observed for both products within the first 12-14 weeks of incubation and stabilized afterwards varying in a range of 4.19-7.08 log CFU/g. Interestingly, higher incubation temperature, especially in WBC2, led to lower yeast counts, concurrently with higher diversity of yeast species. Observed decrease in yeast counts was, most likely, due to negative interactions between yeast species leading to growth inhibition. In total, 469 yeast isolates from WBC1 and WBC2 were genotypically classified using the (GTG)-rep-PCR technique. Out of them, 132 representative isolates were further identified by sequencing the D1/D2 domain of the 26 S rRNA gene. Predominant yeast species in WBCs were Candida zeylanoides and Debaryomyces hansenii, while Candida parapsilosis, Kazachstania bulderi, Kluyveromyces lactis, Pichia fermentans, Pichia kudriavzevii, Rhodotorula mucilaginosa, Torulaspora delbrueckii, and Wickerhamomyces anomalus were found in lower frequency. Heterogeneity of yeast species in WBC2 was generally larger compared to WBC1. This study indicated that, along with contamination levels, taxonomic heterogeneity of yeasts is an important factor influencing yeast cell counts, as well as product quality during storage.
Topics: Cheese; Yeasts; Polymerase Chain Reaction
PubMed: 37098422
DOI: 10.1016/j.fm.2023.104266 -
Journal of Clinical Microbiology May 2001An outbreak of nosocomial fungemia due to the unusual yeast, Pichia anomala occurred in the pediatric wards of our hospital over a period of 23 months (April 1996 to...
An outbreak of nosocomial fungemia due to the unusual yeast, Pichia anomala occurred in the pediatric wards of our hospital over a period of 23 months (April 1996 to February 1998). A total of 379 neonates and children (4.2% admissions) were infected. The probable index case was admitted to the pediatric emergency ward, with subsequent transmission to the premature nursery, pediatric intensive care units, and other children wards. Carriage on the hands of health care personnel was likely to be responsible for dissemination of the fungus. The outbreak could only be controlled after a health education campaign to improve hand-washing practices was instituted and after nystatin-fluconazole prophylaxis to all premature neonates and high-risk infants was introduced. In a case-control study, we identified a lower gestational age, a very low birth weight (<1,500 g), and a longer duration of hospital stay as significant risk factors associated with P. anomala fungemia in premature neonates. We conducted a culture prevalence survey of 50 consecutive premature neonates and found that 28% were colonized with P. anomala at a skin or mucosal site on the date of delivery and that 20% of these neonates subsequently developed P. anomala fungemia. We performed multilocus enzyme electrophoresis on 40 P. anomala outbreak isolates (including patient and health care workers' hand isolates), and the results suggested that these isolates were identical. Our study highlights the importance of P. anomala as an emerging nosocomial fungal pathogen.
Topics: Antifungal Agents; Case-Control Studies; Cross Infection; Disease Outbreaks; Female; Fungemia; Hand; Hospitals; Humans; India; Infant; Infant, Newborn; Infant, Premature; Infant, Premature, Diseases; Male; Microbial Sensitivity Tests; Mycoses; Pediatrics; Pichia; Risk Factors; Skin
PubMed: 11325977
DOI: 10.1128/JCM.39.5.1702-1706.2001 -
Medical Mycology Oct 2019Although Cyberlindnera fabinaii is a rare opportunist yeast species, its ability to cause septicemia, produce biofilm, and rapid acquisition of resistance to fluconazole... (Review)
Review
Unequivocal identification of an underestimated opportunistic yeast species, Cyberlindnera fabianii, and its close relatives using a dual-function PCR and literature review of published cases.
Although Cyberlindnera fabinaii is a rare opportunist yeast species, its ability to cause septicemia, produce biofilm, and rapid acquisition of resistance to fluconazole and voriconazole, reinforced the urge for its identification from its closely related species. Widely used biochemical assays mainly identify Cyberlindnera fabinaii as Cyberlindnera jadinii and Wickerhamomyces anomalus, resulting in underestimation of this yeast in clinical settings. Moreover, the urge for a reliable molecular means of identification remains unsolved for 28 years. In order to unequivocally differentiate Cy. fabianii, Cy. mississipiensis, Cy. jadinii, and W. anomalus, we designed a dual-function multiplex polymerase chain reaction (PCR) assay. Challenging our dual-function multiplex PCR assay with 30 most clinically important yeast species, proved its specificity. Although conventional PCR could differentiate four target species, the real-time PCR counterpart due to Tm overlap misidentified Cy. mississipiensis as Cy. jadinii. Alongside of presenting a comprehensive literature review of published cases of Cy. fabianii from 1990 to 2018, we collected various clinical isolates from Tehran, Shiraz, and Fasa (July 1, 2017, to December 31, 2017) to find a passive relative distribution of these closely-related species in Iran. Subjecting our Iranian collection of yeast isolates to matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) MS and LSU and ITS rDNA sequencing revealed six isolates of Cy. fabianii (central venous catheter n = 2 and vaginal swabs n = 4) and one isolate of Cy. jadinii (vaginal swabs). Due to the use of biochemical assays in global ARTEMIS study, we encourage reidentification of clinical isolates of Cy. jadinii and Cy. jadinii using MALDI-TOF or Sanger sequencing that might lead to correcting the distribution of this fungus.
Topics: Antifungal Agents; DNA Primers; DNA, Ribosomal; Female; Humans; Iran; Male; Multiplex Polymerase Chain Reaction; Mycoses; Saccharomycetales; Sensitivity and Specificity; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Vagina
PubMed: 30649481
DOI: 10.1093/mmy/myy148 -
Frontiers in Microbiology 2020To increase the safety and quality of baijiu and rice wine in China, controlling the use of traditional by studying the beneficial yeasts present has recently been...
To increase the safety and quality of baijiu and rice wine in China, controlling the use of traditional by studying the beneficial yeasts present has recently been considered. The fungal diversity of six Chinese including five traditional and one commercial samples was investigated to screen fermentative yeasts with low yields of higher alcohols. A high throughput sequencing approach detected fifteen fungal species with relative abundance higher than 1%, and displayed dissimilarities of fungal diversity among samples. The 15 fungal species were composed of 11 filamentous fungi with as the most common specie and four yeast species, containing , , , and . Classic culture-dependent approaches, including 5.8S-ITS-RFLP analysis and D1/D2 sequencing of the 26S rRNA gene, identified nine yeast species in the five traditional Chinese . In addition to the four yeast species also detected by high throughput sequencing approach, the other five yeast species isolated were , , , , and . Further micro-fermentations of rice wine were performed using 19 single yeast isolates, and after the fermentation of rice wine, higher alcohols and ethanol were analyzed by gas chromatography. Two yeast strains, FBKL2.8022 and FBKL2.8023, were found to have low yields of higher alcohols and could produce 11.70%vol and 7.10%vol ethanol separately. This study for the first time, to the best of our knowledge, explored the fungal resources in traditional from different regions of Guizhou, China. The screened and strains could be used to establish specific starters to promote the standardization of the production of baijiu and rice wine.
PubMed: 32983066
DOI: 10.3389/fmicb.2020.02103 -
Frontiers in Bioengineering and... 2024Polyalcohols such as arabitol are among the main targets of biorefineries aiming to upcycle wastes and cheap substrates. In previous works WC 1501 emerged as an...
Polyalcohols such as arabitol are among the main targets of biorefineries aiming to upcycle wastes and cheap substrates. In previous works WC 1501 emerged as an excellent arabitol producer utilizing glycerol. Arabitol production by this strain is not growth associated, therefore, in this study, pre-grown cells were entrapped in calcium alginate beads (AB) and utilized for glycerol transformation to arabitol. Flasks experiments aimed to assess the medium composition (i.e., the concentration of inorganic and organic nitrogen sources and phosphates) and to establish the appropriate carrier-to-medium proportion. In flasks, under the best conditions of ammonium limitation and the carrier:medium ratio of 1:3 (w/v), 82.7 g/L glycerol were consumed in 168 h, yielding 31.2 g/L arabitol, with a conversion of 38% and volumetric productivity of 186 mg/mL/h. The process with immobilized cells was transferred to laboratory scale bioreactors with different configurations: stirred tank (STR), packed bed (PBR), fluidized bed (FBR), and airlift (ALR) bioreactors. The STR experienced oxygen limitation due to the need to maintain low stirring to preserve AB integrity and performed worse than flasks. Limitations in diffusion and mass transfer of oxygen and/or nutrients characterized also the PBR and the FBR and were partially relieved only in ALR, where 89.4 g/L glycerol were consumed in 168 h, yielding 38.1 g/L arabitol, with a conversion of 42% and volumetric productivity of 227 mg/mL/h. When the ALR was supplied with successive pulses of concentrated glycerol to replenish the glycerol as it was being consumed, 117 g/L arabitol were generated in 500 h, consuming a total of 285 g/L glycerol, with a 41% and 234 mg/L/h. The study strongly supports the potential of WC 1501 for efficient glycerol-to-arabitol conversion using immobilized cells. While the yeast shows promise by remaining viable and active for extended periods, further optimization is required, especially regarding mixing and oxygenation. Improving the stability of the immobilization process is also crucial for reusing pre-grown cells in multiple cycles, reducing dead times, biomass production costs, and enhancing the economic feasibility of the process.
PubMed: 38659644
DOI: 10.3389/fbioe.2024.1375937 -
Frontiers in Microbiology 2018This study evaluated the efficacy of the essential oil from L. (MSEO) and . × Huds. (MVEO) to inactivate and in Sabouraud dextrose broth and cashew, guava, mango,...
This study evaluated the efficacy of the essential oil from L. (MSEO) and . × Huds. (MVEO) to inactivate and in Sabouraud dextrose broth and cashew, guava, mango, and pineapple juices during 72 h of refrigerated storage. The effects of the incorporation of an anti-yeast effective dose of MSEO on some physicochemical and sensory characteristics of juices were evaluated. The incorporation of 3.75 μL/mL MSEO or 15 μL/mL MVEO caused a ≥5-log reductions in counts of , and in Sabouraud dextrose broth. In cashew and guava juices, 1.875 μL/mL MSEO or 15 μL/mL MVEO caused ≥5-log reductions in counts of and . In pineapple juice, 3.75 μL/mL MSEO caused ≥5-log reductions in counts of and ; 15 μL/mL MVEO caused ≥5-log reductions in counts of in mango juice. The incorporation of 1.875 μL/mL MSEO did not affect the physicochemical parameters of juices and did not induce negative impacts to cause their possible sensory rejection. These results show the potential of MSEO and MVEO, primarily MSEO, to comprise strategies to control spoilage yeasts in fruit juices.
PubMed: 29887860
DOI: 10.3389/fmicb.2018.01111 -
Animal Bioscience Apr 2022This study aimed to determine the appropriate supplementation level of lactic acid bacteria (LAB; Lactobacillus plantarum and Bacillus clausii), yeast (Saccharomyces...
Effect of lactic acid bacteria and yeast supplementation on anti-nutritional factors and chemical composition of fermented total mixed ration containing cottonseed meal or rapeseed meal.
OBJECTIVE
This study aimed to determine the appropriate supplementation level of lactic acid bacteria (LAB; Lactobacillus plantarum and Bacillus clausii), yeast (Saccharomyces cariocanus and Wickerhamomyces anomalus) for degrading free gossypol and glucosinolate in the fermented total mixed ration (TMR) containing cottonseed meal (CSM) or rapeseed meal (RSM), to improve the utilization efficiency of these protein sources.
METHODS
For LAB, L. plantarum or B. clausii was inoculated at 1.0×108, 1.0×109, 1.0×1010, and 1.0×1011 colony-forming unit (CFU)/kg dry matter (DM), respectively. For yeast, S. cariocanus or W. anomalus was inoculated at 5×106, 5×107, 5×108, and 5×109 CFU/kg DM, respectively. The TMR had 50% moisture and was incubated at 30°C for 48 h. After fermentation, the chemical compositions, and the contents of free gossypol and glucosinolate were determined.
RESULTS
The results showed that the concentration of free gossypol content was reduced (p<0.05), while that of the crude protein content was increased (p<0.05) in the TMR containing CSM inoculated by B. clausii (1×109 CFU/kg DM) or S. cariocanus (5×109 CFU/kg DM). Similarly, the content of glucosinolate was lowered (p<0.05) and the crude protein content was increased (p<0.05) in TMR containing RSM inoculated with B. clausii (1×1010 CFU/kg DM) or S. cariocanus (5×109 CFU/g DM).
CONCLUSION
This study confirmed that inclusion of B. clausii with 1.0×109 or 1.0×1010 CFU/kg DM, or S. cariocanus (5×109 CFU/kg DM) to TMR containing CSM/RSM improved the nutritional value and decreased the contents of anti-nutritional factors.
PubMed: 34530504
DOI: 10.5713/ab.21.0270 -
Journal of Applied Microbiology Feb 2006Investigate the survival of liquid formulations of the biocontrol yeast Pichia anomala J121 at different temperatures, and develop a system for comparative studies of...
AIMS
Investigate the survival of liquid formulations of the biocontrol yeast Pichia anomala J121 at different temperatures, and develop a system for comparative studies of different storage conditions and formulations.
METHODS AND RESULTS
The survival of P. anomala in liquid formulations with lactose, starch and trehalose amendments was measured during prolonged storage at temperatures ranging from -20 to +30 degrees C. The relative survival of the stored cells was rapidly estimated by flow cytometry. After 4 weeks incubation at 4 and 10 degrees C, 75-90% of the cells were viable, with no significant differences between the various formulations. Supplementing the storage buffer with lactose or trehalose increased the survival after longer incubations (8 and 12 weeks) at all temperatures (-20 to 30 degrees C). Trehalose was the most effective protectant at 20 and 30 degrees C (>20% viable cells after 12 weeks at 20 degrees C). The biocontrol activity was maintained after formulation and prolonged storage of P. anomala.
CONCLUSIONS
The storage potential of liquid formulated P. anomala cells can be increased by supplementation with lactose or trehalose. The combination of a custom made incubation chamber and flow cytometry was suitable to evaluate stability of P. anomala formulations.
SIGNIFICANCE AND IMPACT OF THE STUDY
Liquid formulated P. anomala have a long shelf life. The developed test system can be used to study different formulations of other biocontrol agents.
Topics: Colony Count, Microbial; Edible Grain; Fermentation; Flow Cytometry; Food Handling; Lactose; Pest Control, Biological; Pichia; Starch; Temperature; Time Factors; Trehalose
PubMed: 16430502
DOI: 10.1111/j.1365-2672.2005.02778.x -
Journal of Applied Microbiology Nov 2010To enumerate the micro-organisms and to identify the yeast species present during the ensilage of different sugarcane (Saccharum spp.) cultivars.
AIMS
To enumerate the micro-organisms and to identify the yeast species present during the ensilage of different sugarcane (Saccharum spp.) cultivars.
METHOD
Samples of sugarcane silage were collected at 10, 20, 30 and 40 days from the start of fermentation. Population levels of lactic acid bacteria (LAB), mesophilic facultative anaerobic (MFA) bacteria, filamentous fungi and yeasts were determined. Nine species of yeasts were classified according to traditional methods and confirmed using molecular techniques.
CONCLUSIONS
LAB dominated the ensiling process of sugarcane, although yeasts were present at relatively high population levels throughout the whole fermentation period. The detected species of yeasts varied according to sugarcane cultivar and time of fermentation. Torulaspora delbrueckii was the predominant yeast, followed by Pichia anomala and Saccharomyces cerevisiae.
SIGNIFICANCE AND IMPACT OF THE STUDY
Knowledge of the population of micro-organisms in general, and of yeasts in particular, present during the fermentation of sugarcane is of fundamental importance in the development of more effective ensiling processes.
Topics: Colony Count, Microbial; Fermentation; Hydrogen-Ion Concentration; Saccharum; Silage; Time Factors; Yeasts
PubMed: 20618886
DOI: 10.1111/j.1365-2672.2010.04796.x -
Antimicrobial Agents and Chemotherapy Jan 1989Pichia anomala WC 65 secretes a toxin that is inhibitory to a variety of yeasts, including strains of the animal pathogen Candida albicans. The toxin was purified to...
Pichia anomala WC 65 secretes a toxin that is inhibitory to a variety of yeasts, including strains of the animal pathogen Candida albicans. The toxin was purified to homogeneity by ultrafiltration, ethanol precipitation, ion-exchange chromatography with a Mono Q column, and gel permeation chromatography with a Superose 12 column. The toxin had a molecular weight of 83,300 as determined by electrophoresis on sodium dodecyl sulfate-polyacrylamide gradient gels and a molecular weight of 85,290 as determined by gel permeation chromatography. The isoelectric point of the toxin was pH 5.0. The toxin was stable between pH 2.0 and 5.0. Chemical analysis of the purified toxin indicated that the toxin was a glycoprotein composed of about 86% protein and 14% carbohydrate. At high concentrations, the toxin showed a tendency to aggregate, with loss of biological activity against C. albicans, Pichia bimundalis, and Saccharomycodes ludwigii. Purified toxin expressed killing activity against C. albicans in contrast to the static activity of the crude toxin.
Topics: Candida albicans; Chromatography, Gel; Chromatography, Ion Exchange; Electrophoresis, Polyacrylamide Gel; Mycotoxins; Pichia; Saccharomycetales
PubMed: 2653213
DOI: 10.1128/AAC.33.1.48