scholarly journals Assessment of orange fruit colonization by biocontrol yeasts

2017 ◽  
Vol 38 (SI 2 - 6th Conf EFPP 2002) ◽  
pp. 638-641
Author(s):  
V. Coco ◽  
V. Grimaldi ◽  
A. Campisano ◽  
L. Strano ◽  
A. Catara
Keyword(s):  
Debaryomyces Hansenii ◽  
Morphological Diversity ◽  
Tween 80 ◽  
Yeast Cells ◽  
Scanning Electron Microscope Study ◽  
Naturally Occurring ◽  
Colonization Process ◽  
Orange Fruit ◽  
Surface Waxes ◽  
Green Mould

A scanning electron microscope study of citrus fruits was performed to assess the colonization process of antagonistic yeasts to green mould of Tarocco oranges under artificial inoculation. Yeast suspensions of Debaryomyces hansenii DBVPG 4025, Pichia guilliermondii NRRL Y 18134, P. anomala J121 and Saccharomyces cerevisiae P1.6 with or without addition of 1% CaCl<sub>2</sub> + 0.1% Tween 80 were evaluated. Penicillium digitatum was sprayed one hour later. Observation of fruit surface waxes revealed marked morphological diversity. Yeast cells and conidia were mostly localized on epicuticular waxes, particularly in naturally occurring small pits. The size of the wound affected the number of yeasts and conidia penetrating inside. Treatment with CaCl<sub>2</sub> did not affect the waxes and/or the behaviour of the yeasts and pathogen.

scholarly journals Formulation, characterization and stability of o/w nanoemulsion containing rice bran oil prepared by emulsion phase inversion

Food Research ◽  
2020 ◽  
Vol 4 (4) ◽  
pp. 1025-1029
Author(s):  
Y.P. Sari ◽  
S. Raharjo ◽  
U. Santoso ◽  
Supriyadi
Keyword(s):  
Rice Bran ◽  
Phase Inversion ◽  
Rice Bran Oil ◽  
Coconut Oil ◽  
Tween 80 ◽  
Polydispersity Index ◽  
Inversion Method ◽  
Emulsion Phase ◽  
Naturally Occurring ◽  
Phase Inversion Method

Rice bran oil (RBO) contains naturally occurring antioxidants such as carotenoids, tocopherol, and γ-oryzanol. The aim of this research was to formulate and evaluate the characteristics of nanoemulsion which was prepared using RBO containing naturally occurring antioxidants. The RBO-in-water nanoemulsion was prepared by the emulsion phase inversion method. The oil phase of the nanoemulsion was prepared by either virgin coconut oil (VCO) or palm oil (PO) combined with RBO with the ratio of 5:5; 4:6, 3:7, 2:8 and 0:10. Tween 80 was used as a surfactant. The surfactant to oil ratios was predetermined at 2.5:1.0 and 3.0:1.0. The aqueous phase (80% w/w) was titrated into an organic phase that consisted of Tween 80 and oil phase (approximately 20% w/w). Droplet size, zeta-potential and polydispersity index of the nanoemulsion were used as the main parameters. The results showed that the smallest droplet (<100 nm) of the nanoemulsion was obtained when the ratio of VCO: RBO at 3:7 and the ratio of PO: RBO at 4:6 with the surfactant to oil ratio (SOR) was 2.5. Nanoemulsion with a relatively small polydispersity index of 0.3 was achieved when the ratio of PO: RBO was 3:7 and SOR at 3. All of the freshly prepared RBO containing nanoemulsion have good stability with zetapotential values of < -30 mV. Nanoemulsions were stable against centrifugation at 2300 rpm for 15 mins, but they were not stable against heating at 105°C for 5 hrs. The RBO-inwater nanoemulsion could be successfully prepared by phase inversion method, by combining RBO with either VCO or PO at different ratios.

scholarly journals Candida albicans Hyphal Formation and Virulence Assessed Using a Caenorhabditis elegans Infection Model

2009 ◽  
Vol 8 (11) ◽  
pp. 1750-1758 ◽  
Author(s):  
Read Pukkila-Worley ◽  
Anton Y. Peleg ◽  
Emmanouil Tampakakis ◽  
Eleftherios Mylonakis
Keyword(s):  
Candida Albicans ◽  
Caenorhabditis Elegans ◽  
Debaryomyces Hansenii ◽  
Yeast Cells ◽  
Infection Model ◽  
Virulence Determinants ◽  
Tissue Destruction ◽  
C Elegans ◽  
Hyphal Formation

ABSTRACT Candida albicans colonizes the human gastrointestinal tract and can cause life-threatening systemic infection in susceptible hosts. We study here C. albicans virulence determinants using the nematode Caenorhabditis elegans in a pathogenesis system that models candidiasis. The yeast form of C. albicans is ingested into the C. elegans digestive tract. In liquid media, the yeast cells then undergo morphological change to form hyphae, which results in aggressive tissue destruction and death of the nematode. Several lines of evidence demonstrate that hyphal formation is critical for C. albicans pathogenesis in C. elegans. First, two yeast species unable to form hyphae (Debaryomyces hansenii and Candida lusitaniae) were less virulent than C. albicans in the C. elegans assay. Second, three C. albicans mutant strains compromised in their ability to form hyphae (efg1Δ/efg1Δ, flo8Δ/flo8Δ, and cph1Δ/cph1Δ efg1Δ/efg1Δ) were dramatically attenuated for virulence. Third, the conditional tet-NRG1 strain, which enables the external manipulation of morphogenesis in vivo, was more virulent toward C. elegans when the assay was conducted under conditions that permit hyphal growth. Finally, we demonstrate the utility of the C. elegans assay in a screen for C. albicans virulence determinants, which identified several genes important for both hyphal formation in vivo and the killing of C. elegans, including the recently described CAS5 and ADA2 genes. These studies in a C. elegans-C. albicans infection model provide insights into the virulence mechanisms of an important human pathogen.

scholarly journals The Mode of Action of Silver and Silver Halides Nanoparticles against Saccharomyces cerevisiae Cells

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
A. A. Kudrinskiy ◽  
A. Yu. Ivanov ◽  
E. V. Kulakovskaya ◽  
A. I. Klimov ◽  
P. M. Zherebin ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Silver Nitrate ◽  
Silver Ions ◽  
Tween 80 ◽  
Cell Loss ◽  
Yeast Cells ◽  
Silver Halides ◽  
Silver Nps ◽  
Sodium Borohydride Reduction ◽  
Synthesized Materials

Silver and silver halides nanoparticles (NPs) (Ag, AgCl, AgBr, and AgI) capped with two different stabilizers (sodium citrate and nonionic surfactant Tween 80) were obtained via sodium borohydride reduction of silver nitrate in an aqueous solution. The effect of the biocidal action of as-prepared synthesized materials against yeast cells Saccharomyces cerevisiae was compared to the effect produced by silver nitrate and studied through the measurement of cell loss and kinetics of K+ efflux from the cells depending on concentration of silver. The results clearly indicate that the silver ions either remained in the dispersion of silver NPs and silver halides NPs after their synthesis or were generated afterwards by dissolving silver and silver halides particles playing a major part in the cytotoxic activity of NPs against yeast cells. It was also supposed that this activity most likely does not relate to the damage of cell membrane.

Detection, Isolation and Identification of Osmotolerant Yeasts from High-Sugar Products

1987 ◽  
Vol 50 (6) ◽  
pp. 468-472 ◽  
Author(s):  
MARCO F. G. JERMINI ◽  
OTTO GEIGES ◽  
WILHELM SCHMIDT-LORENZ
Keyword(s):  
Yeast Extract ◽  
Enrichment Culture ◽  
Debaryomyces Hansenii ◽  
Yeast Cells ◽  
Isolation And Identification ◽  
Torulaspora Delbrueckii ◽  
Enrichment Medium ◽  
Zygosaccharomyces Bailii ◽  
Zygosaccharomyces Rouxii ◽  
High Sugar

A simple presence-absence test for detection of small numbers of osmotolerant yeasts in foods was developed. Yeast extract glucose 50 broth [consisting of 0.5% (w/w) yeast extract and 50% (w/w) glucose] was used as enrichment medium and was incubated with agitation at 30°C. The detection was done by (a) microscope and (b) streaking 0.03 ml of enrichment culture on selective yeast extract glucose 50 agar and incubation at 30°C for 5–7 d. If no yeast cells were observed under the microscope within 10 d of incubation, the product sample was judged as “free from osmotolerant yeasts.” In accordance with this method 28 strains of osmotolerant yeasts were isolated from 27 spoiled high-sugar products. Twenty-four strains were identified as Zygosaccharomyces rouxii, 2 Zygosaccharomyces bailii and 1 each as Torulaspora delbrueckii and Debaryomyces hansenii.

Naturally Occurring Biofilms on Alfalfa and Other Types of Sprouts†

2000 ◽  
Vol 63 (5) ◽  
pp. 625-632 ◽  
Author(s):  
WILLIAM F. FETT
Keyword(s):  
Yeast Cells ◽  
Escherichia Coli O157 ◽  
Antimicrobial Compounds ◽  
Human Pathogens ◽  
Free Living ◽  
Plant Parts ◽  
Naturally Occurring ◽  
Retail Outlets ◽  
Alfalfa Sprouts ◽  
Bacterial Exopolysaccharides

Scanning electron microscopy was used to examine the cotyledons, hypocotyls, and roots of alfalfa, broccoli, clover, and sunflower sprouts purchased from retail outlets as well as alfalfa sprouts grown in the laboratory using a tray system equipped with automatic irrigation. Biofilms were observed on all plant parts of the four types of commercially grown sprouts. Biofilms were also commonly observed on alfalfa sprouts grown in the laboratory by 2 days of growth. Rod-shaped bacteria of various sizes were predominant on all sprouts examined both as free-living cells and as components of biofilms. Occasionally, cocci-shaped bacteria as well as yeast cells were also present in biofilms. The microbes contained in the biofilms appeared to be attached to each other and to the plant surface by a matrix, most likely composed of bacterial exopolysaccharides. Biofilms were most abundant and of the largest dimensions on cotyledons, sometimes covering close to the entire cotyledon surface (approximately 2 mm in length). Naturally occurring biofilms on sprouts may afford protected colonization sites for human pathogens such as Salmonella and Escherichia coli O157:H7, making their eradication with antimicrobial compounds difficult.

scholarly journals THE BIOGENESIS OF MITOCHONDRIA

1968 ◽  
Vol 37 (2) ◽  
pp. 207-220 ◽  
Author(s):  
P. G. Wallace ◽  
M. Huang ◽  
Anthony W. Linnane
Keyword(s):  
Growth Medium ◽  
Mitochondrial Membrane ◽  
Plasma Membranes ◽  
Unsaturated Fatty Acids ◽  
Glucose Repression ◽  
Tween 80 ◽  
Vacuolar Membrane ◽  
Yeast Cells ◽  
Complex Spectrum ◽  
Nutritive Medium

Yeast cells grown anaerobically have been shown to vary in their ultrastructure and absorption spectrum depending upon the composition of the growth medium. The changes observed in the anaerobically grown cells are governed by the availability of unsaturated fatty acids and ergosterol and a catabolite or glucose repression. All the cells contain nuclear and plasma membranes, but the extent of the occurrence of vacuolar and mitochondrial membranes varies greatly with the growth conditions. Cells grown anaerobically on the least nutritive medium, composed of 0.5% Difco yeast extract-5% glucose-inorganic salts (YE-G), appear to contain little vacuolar membrane and no clearly recognizable mitochondrial profiles. Cells grown anaerobically on the YE-G medium supplemented with Tween 80 and ergosterol contain clearly recognizable vacuolar membrane and some mitochondrial profiles, albeit rather poorly defined. Cells grown on YE-G medium supplemented only with Tween 80 are characterized by the presence of large amounts of cytoplasmic membrane in addition to vacuolar membrane and perhaps some primitive mitochondrial profiles. When galactose replaces glucose as the major carbon source in the medium, the mitochondrial profiles within the cytoplasm become more clearly recognizable and their number increases. In aerobically grown cells, the catabolite repression also operates to reduce the total number of mitochondrial profiles. The possibility is discussed that cells grown anaerobically on the YE-G medium may not contain mitochondrial membrane and, therefore, that such cells, on aeration, form mitochondrial membrane from nonmitochondrial sources. A wide variety of absorption compounds is observed in anaerobically grown cells which do not correspond to any of the classical aerobic yeast cytochromes. The number and relative proportions of these anaerobic compounds depend upon the composition of the growth medium, the most complex spectrum being found in cells grown in the absence of lipid supplements.

scholarly journals Yeast Microbiota during Sauerkraut Fermentation and Its Characteristics

2020 ◽  
Vol 21 (24) ◽  
pp. 9699
Author(s):  
Paweł Satora ◽  
Magdalena Skotniczny ◽  
Szymon Strnad ◽  
Katarína Ženišová
Keyword(s):  
Debaryomyces Hansenii ◽  
Low Ph ◽  
Yeast Cells ◽  
Rrna Gene ◽  
Rhodotorula Mucilaginosa ◽  
Active Growth ◽  
Spontaneous Fermentation ◽  
Killer Toxins ◽  
Rapd Pcr ◽  
Clavispora Lusitaniae

Sauerkraut is the most important fermented vegetable obtained in Europe. It is produced traditionally by spontaneous fermentation of cabbage. The aim of this study was to determine biodiversity of yeasts present during fermentation of eight varieties of cabbages (Ambrosia, Avak, Cabton, Galaxy, Jaguar, Kamienna Głowa, Manama and Ramco), as well as characterize obtained yeast isolates. WL Nutrient Agar with Chloramphenicol was used to enumerate yeast. Isolates were differentiated using RAPD-PCR and identified by sequencing of the 5.8S-ITS rRNA gene region. The volatiles production was analyzed using SPME-GC-TOFMS. Our research confirmed that during sauerkraut fermentation there is an active growth of the yeasts, which begins in the first phases. The maximal number of yeast cells from 1.82 to 4.46 log CFU g−1 occurred after 24 h of fermentation, then decrease in yeast counts was found in all samples. Among the isolates dominated the cultures Debaryomyces hansenii, Clavispora lusitaniae and Rhodotorula mucilaginosa. All isolates could grow at NaCl concentrations higher than 5%, were relatively resistant to low pH and the presence of lactic acid, and most of them were characterized by killer toxins activity. The highest concentration of volatiles (mainly esters and alcohols) were produced by Pichia fermentans and D. hansenii strains.

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